1
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Zhang R, Zhang C, Fan X, Au Yeung CCK, Li H, Lin H, Shum HC. A droplet robotic system enabled by electret-induced polarization on droplet. Nat Commun 2024; 15:6220. [PMID: 39043732 PMCID: PMC11266649 DOI: 10.1038/s41467-024-50520-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2023] [Accepted: 07/12/2024] [Indexed: 07/25/2024] Open
Abstract
Robotics for scientific research are evolving from grasping macro-scale solid materials to directly actuating micro-scale liquid samples. However, current liquid actuation mechanisms often restrict operable liquid types or compromise the activity of biochemical samples by introducing interfering mediums. Here, we propose a robotic liquid handling system enabled by a novel droplet actuation mechanism, termed electret-induced polarization on droplet (EPD). EPD enables all-liquid actuation in principle and experimentally exhibits generality for actuating various inorganic/organic liquids with relative permittivity ranging from 2.25 to 84.2 and volume from 500 nL to 1 mL. Moreover, EPD is capable of actuating various biochemical samples without compromising their activities, including various body fluids, living cells, and proteins. A robotic system is also coupled with the EPD mechanism to enable full automation. EPD's high adaptability with liquid types and biochemical samples thus promotes the automation of liquid-based scientific experiments across multiple disciplines.
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Affiliation(s)
- Ruotong Zhang
- Department of Mechanical Engineering, The University of Hong Kong, Hong Kong SAR, China
| | - Chengzhi Zhang
- Department of Mechanical Engineering, The University of Hong Kong, Hong Kong SAR, China
- Department of Materials Science and Engineering, Southern University of Science and Technology, Shenzhen, Guangdong, China
| | - Xiaoxue Fan
- Department of Mechanical Engineering, The University of Hong Kong, Hong Kong SAR, China
| | - Christina C K Au Yeung
- Department of Mechanical Engineering, The University of Hong Kong, Hong Kong SAR, China
- Advanced Biomedical Instrumentation Centre, Hong Kong Science Park, Hong Kong SAR, China
| | - Huiyanchen Li
- Advanced Biomedical Instrumentation Centre, Hong Kong Science Park, Hong Kong SAR, China
| | - Haisong Lin
- Department of Mechanical Engineering, The University of Hong Kong, Hong Kong SAR, China.
- Advanced Biomedical Instrumentation Centre, Hong Kong Science Park, Hong Kong SAR, China.
| | - Ho Cheung Shum
- Department of Mechanical Engineering, The University of Hong Kong, Hong Kong SAR, China.
- Advanced Biomedical Instrumentation Centre, Hong Kong Science Park, Hong Kong SAR, China.
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2
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Bohm S, Phi HB, Dittrich L, Runge E. Chip-integrated non-mechanical microfluidic pump driven by electrowetting on dielectrics. LAB ON A CHIP 2024; 24:2893-2905. [PMID: 38656325 DOI: 10.1039/d4lc00178h] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/26/2024]
Abstract
A microfluidic pump is presented that generates its pumping action via the EWOD (electrowetting-on-dielectric) effect. The flow is generated by the periodic movement of liquid-vapor interfaces in a large number (≈106) of microcavities resulting in a volume change of approx. 0.5 pl per cavity per pump stroke. The total flow resulting from all microcavities adds up to a few hundred nanolitres per cycle. Passive, topologically optimized, non-mechanical Tesla valves are used to rectify the flow. As a result, the micropump operates without any moving components. The dimensioning, fabrication, and characterization process of the micropump are described. Device fabrication is done using conventional manufacturing processes from microsystems technology, enabling cost-effective mass production on wafer-level without additional assembly steps like piezo chip-level bonding, etc. This allows for direct integration into wafer-based microfluidic or lab-on-a-chip applications. Furthermore, first measurement results obtained with prototypes of the micropump are presented. The voltage- and frequency-dependent pump performance is determined. The measurements show that a continuous flow rate larger than 0.2 ml min-1 can be achieved at a maximum pump pressure larger than 12 mbar.
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Affiliation(s)
- Sebastian Bohm
- Institute of Physics, Group 'Theoretical Physics I', Technische Universität Ilmenau, Weimarer Straße 25, 98693 Ilmenau, Germany.
- Institute of Micro- and Nanotechnologies, Technische Universität Ilmenau, Gustav-Kirchhoff-Straße 7, 98693 Ilmenau, Germany
- 5microns GmbH, Margarethenstraße 6, 98693 Ilmenau, Germany
| | - Hai Binh Phi
- Institute of Micro- and Nanotechnologies, Technische Universität Ilmenau, Gustav-Kirchhoff-Straße 7, 98693 Ilmenau, Germany
- 5microns GmbH, Margarethenstraße 6, 98693 Ilmenau, Germany
| | - Lars Dittrich
- Institute of Micro- and Nanotechnologies, Technische Universität Ilmenau, Gustav-Kirchhoff-Straße 7, 98693 Ilmenau, Germany
- 5microns GmbH, Margarethenstraße 6, 98693 Ilmenau, Germany
| | - Erich Runge
- Institute of Physics, Group 'Theoretical Physics I', Technische Universität Ilmenau, Weimarer Straße 25, 98693 Ilmenau, Germany.
- Institute of Micro- and Nanotechnologies, Technische Universität Ilmenau, Gustav-Kirchhoff-Straße 7, 98693 Ilmenau, Germany
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3
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Zeng Y, Gan X, Xu Z, Hu X, Hu C, Ma H, Tu H, Chai B, Yang C, Hu S, Chai Y. AIEgens-enhanced rapid sensitive immunofluorescent assay for SARS-CoV-2 with digital microfluidics. Anal Chim Acta 2024; 1298:342398. [PMID: 38462346 DOI: 10.1016/j.aca.2024.342398] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2023] [Revised: 02/14/2024] [Accepted: 02/20/2024] [Indexed: 03/12/2024]
Abstract
BACKGROUND Sensitive and rapid antigen detection is critical for the diagnosis and treatment of infectious diseases, but conventional ELISAs including chemiluminescence-based assays are limited in sensitivity and require many operation steps. Fluorescence immunoassays are fast and convenient but often show limited sensitivity and dynamic range. RESULTS To address the need, an aggregation-induced emission fluorgens (AIEgens) enhanced immunofluorescent assay with beads-based quantification on the digital microfluidic (DMF) platform was developed. Portable DMF devices and chips with small electrodes were fabricated, capable of manipulating droplets within 100 nL and boosting the reaction efficiency. AIEgen nanoparticles (NPs) with high fluorescence and photostability were synthesized to enhance the test sensitivity and detection range. The integration of AIEgen probes, transparent DMF chip design, and the large magnetic beads (10 μm) as capture agents enabled rapid and direct image-taking and signal calculation of the test result. The performance of this platform was demonstrated by point-of-care quantification of SARS-CoV-2 nucleocapsid (N) protein. Within 25 min, a limit of detection of 5.08 pg mL-1 and a limit of quantification of 8.91 pg mL-1 can be achieved using <1 μL sample. The system showed high reproducibility across the wide dynamic range (10-105 pg mL-1), with the coefficient of variance ranging from 2.6% to 9.8%. SIGNIFICANCE This rapid, sensitive AIEgens-enhanced immunofluorescent assay on the DMF platform showed simplified reaction steps and improved performance, providing insight into the small-volume point-of-care testing of different biomarkers in research and clinical applications.
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Affiliation(s)
- Yuping Zeng
- Guangdong Key Laboratory of Biomedical Measurements and Ultrasound Imaging, School of Biomedical Engineering, Shenzhen University Medical School, Shenzhen University, Shenzhen, 518060, China.
| | - Xiangyu Gan
- Guangdong Key Laboratory of Biomedical Measurements and Ultrasound Imaging, School of Biomedical Engineering, Shenzhen University Medical School, Shenzhen University, Shenzhen, 518060, China.
| | - Zhourui Xu
- Guangdong Key Laboratory of Biomedical Measurements and Ultrasound Imaging, School of Biomedical Engineering, Shenzhen University Medical School, Shenzhen University, Shenzhen, 518060, China.
| | - Xiaoxiang Hu
- Guangdong Key Laboratory of Biomedical Measurements and Ultrasound Imaging, School of Biomedical Engineering, Shenzhen University Medical School, Shenzhen University, Shenzhen, 518060, China.
| | - Chenxuan Hu
- CAS Key Laboratory of Bio-Medical Diagnostics, Suzhou Institute of Biomedical Engineering and Technology, Chinese Academy of Sciences, Suzhou, China.
| | - Hanbin Ma
- CAS Key Laboratory of Bio-Medical Diagnostics, Suzhou Institute of Biomedical Engineering and Technology, Chinese Academy of Sciences, Suzhou, China; Guangdong ACXEL Micro & Nano Tech Co., Ltd, Foshan, Guangdong province, China.
| | - Hangjia Tu
- Guangdong Key Laboratory of Biomedical Measurements and Ultrasound Imaging, School of Biomedical Engineering, Shenzhen University Medical School, Shenzhen University, Shenzhen, 518060, China.
| | - Bao Chai
- Department of Dermatology, Huazhong University of Science and Technology Union Shenzhen Hospital, Shenzhen, 518052, China; Department of Dermatology, The 6th Affiliated Hospital of Shenzhen University Health Science Center, Shenzhen, 518052, China.
| | - Chengbin Yang
- Guangdong Key Laboratory of Biomedical Measurements and Ultrasound Imaging, School of Biomedical Engineering, Shenzhen University Medical School, Shenzhen University, Shenzhen, 518060, China.
| | - Siyi Hu
- CAS Key Laboratory of Bio-Medical Diagnostics, Suzhou Institute of Biomedical Engineering and Technology, Chinese Academy of Sciences, Suzhou, China.
| | - Yujuan Chai
- Guangdong Key Laboratory of Biomedical Measurements and Ultrasound Imaging, School of Biomedical Engineering, Shenzhen University Medical School, Shenzhen University, Shenzhen, 518060, China.
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4
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Chan C, Peng J, Rajesh V, Scott EY, Sklavounos AA, Faiz M, Wheeler AR. Digital Microfluidics for Microproteomic Analysis of Minute Mammalian Tissue Samples Enabled by a Photocleavable Surfactant. J Proteome Res 2023; 22:3242-3253. [PMID: 37651704 DOI: 10.1021/acs.jproteome.3c00281] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 09/02/2023]
Abstract
Proteome profiles of precious tissue samples have great clinical potential for accelerating disease biomarker discovery and promoting novel strategies for early diagnosis and treatment. However, tiny clinical tissue samples are often difficult to handle and analyze with conventional proteomic methods. Automated digital microfluidic (DMF) workflows facilitate the manipulation of size-limited tissue samples. Here, we report the assessment of a DMF microproteomics workflow enabled by a photocleavable surfactant for proteomic analysis of minute tissue samples. The surfactant 4-hexylphenylazosulfonate (Azo) was found to facilitate fast droplet movement on DMF and enhance the proteomics analysis. Comparisons of Azo and n-Dodecyl β-d-maltoside (DDM) using small samples of HeLa digest standards and MCF-7 cell digests revealed distinct differences at the peptide level despite similar results at the protein level. The DMF microproteomics workflow was applied for the sample preparation of ∼3 μg biopsies from murine brain tissue. A total of 1969 proteins were identified in three samples, including established neural biomarkers and proteins related to synaptic signaling. Going forward, we propose that the Azo-enabled DMF workflow has the potential to advance the practical clinical application of DMF for the analysis of size-limited tissue samples.
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Affiliation(s)
- Calvin Chan
- Department of Chemistry, University of Toronto, Toronto M5S 3H6, Ontario, Canada
| | - Jiaxi Peng
- Department of Chemistry, University of Toronto, Toronto M5S 3H6, Ontario, Canada
- Donnelly Centre for Cellular and Biomolecular Research, University of Toronto, Toronto M5S 3E1, Ontario, Canada
- Institute of Biomedical Engineering, University of Toronto, Toronto M5S 3G9, Ontario, Canada
| | - Vigneshwar Rajesh
- Department of Chemistry, University of Toronto, Toronto M5S 3H6, Ontario, Canada
| | - Erica Y Scott
- Department of Chemistry, University of Toronto, Toronto M5S 3H6, Ontario, Canada
- Donnelly Centre for Cellular and Biomolecular Research, University of Toronto, Toronto M5S 3E1, Ontario, Canada
- Institute of Biomedical Engineering, University of Toronto, Toronto M5S 3G9, Ontario, Canada
- Department of Surgery, University of Toronto, Toronto M5S 1A8, Ontario, Canada
| | - Alexandros A Sklavounos
- Department of Chemistry, University of Toronto, Toronto M5S 3H6, Ontario, Canada
- Donnelly Centre for Cellular and Biomolecular Research, University of Toronto, Toronto M5S 3E1, Ontario, Canada
| | - Maryam Faiz
- Department of Surgery, University of Toronto, Toronto M5S 1A8, Ontario, Canada
| | - Aaron R Wheeler
- Department of Chemistry, University of Toronto, Toronto M5S 3H6, Ontario, Canada
- Donnelly Centre for Cellular and Biomolecular Research, University of Toronto, Toronto M5S 3E1, Ontario, Canada
- Institute of Biomedical Engineering, University of Toronto, Toronto M5S 3G9, Ontario, Canada
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5
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Koroyasu Y, Nguyen TV, Sasaguri S, Marzo A, Ezcurdia I, Nagata Y, Yamamoto T, Nomura N, Hoshi T, Ochiai Y, Fushimi T. Microfluidic platform using focused ultrasound passing through hydrophobic meshes with jump availability. PNAS NEXUS 2023; 2:pgad207. [PMID: 37404834 PMCID: PMC10317206 DOI: 10.1093/pnasnexus/pgad207] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/06/2023] [Revised: 05/30/2023] [Accepted: 06/12/2023] [Indexed: 07/06/2023]
Abstract
Applications in chemistry, biology, medicine, and engineering require the large-scale manipulation of a wide range of chemicals, samples, and specimens. To achieve maximum efficiency, parallel control of microlitre droplets using automated techniques is essential. Electrowetting-on-dielectric (EWOD), which manipulates droplets using the imbalance of wetting on a substrate, is the most widely employed method. However, EWOD is limited in its capability to make droplets detach from the substrate (jumping), which hinders throughput and device integration. Here, we propose a novel microfluidic system based on focused ultrasound passing through a hydrophobic mesh with droplets resting on top. A phased array dynamically creates foci to manipulate droplets of up to 300 μL. This platform offers a jump height of up to 10 cm, a 27-fold improvement over conventional EWOD systems. In addition, droplets can be merged or split by pushing them against a hydrophobic knife. We demonstrate Suzuki-Miyaura cross-coupling using our platform, showing its potential for a wide range of chemical experiments. Biofouling in our system was lower than in conventional EWOD, demonstrating its high suitability for biological experiments. Focused ultrasound allows the manipulation of both solid and liquid targets. Our platform provides a foundation for the advancement of micro-robotics, additive manufacturing, and laboratory automation.
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Affiliation(s)
- Yusuke Koroyasu
- School of Informatics, College of Media Arts, Science and Technology, University of Tsukuba, Tsukuba, 305-8550 Ibaraki, Japan
- Graduate School of Comprehensive Human Sciences, University of Tsukuba, Tsukuba, 305-8550 Ibaraki, Japan
| | - Thanh-Vinh Nguyen
- Sensing System Research Center, National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba, 305-8564 Ibaraki, Japan
| | - Shun Sasaguri
- School of Informatics, College of Media Arts, Science and Technology, University of Tsukuba, Tsukuba, 305-8550 Ibaraki, Japan
| | - Asier Marzo
- UPNALab, Department of Mathematics and Computer Engineering, Public University of Navarra, Pamplona, 31006 Navarra, Spain
| | - Iñigo Ezcurdia
- UPNALab, Department of Mathematics and Computer Engineering, Public University of Navarra, Pamplona, 31006 Navarra, Spain
| | - Yuuya Nagata
- Institute for Chemical Reaction Design and Discovery, Hokkaido University, Sapporo, 001-0021 Hokkaido, Japan
| | - Tatsuya Yamamoto
- Faculty of Life and Environmental Sciences, University of Tsukuba, Tsukuba, 305-8577 Ibaraki, Japan
| | - Nobuhiko Nomura
- Faculty of Life and Environmental Sciences, University of Tsukuba, Tsukuba, 305-8577 Ibaraki, Japan
- Microbiology Research Center for Sustainability, University of Tsukuba, Tsukuba, 305-8577 Ibaraki, Japan
- Life Science Center for Survival Dynamics, Tsukuba Advanced Research Alliance, University of Tsukuba, Tsukuba, 305-8577 Ibaraki, Japan
| | - Takayuki Hoshi
- Pixie Dust Technologies, Inc., Chiyoda-ku, 101-0061 Tokyo, Japan
| | - Yoichi Ochiai
- Pixie Dust Technologies, Inc., Chiyoda-ku, 101-0061 Tokyo, Japan
- R&D Center for Digital Nature, University of Tsukuba, Tsukuba, 305-8550 Ibaraki, Japan
- Institute of Library, Information and Media Science, University of Tsukuba, Tsukuba, 305-8550 Ibaraki, Japan
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6
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Peng J, Chan C, Zhang S, Sklavounos AA, Olson ME, Scott EY, Hu Y, Rajesh V, Li BB, Chamberlain MD, Zhang S, Peng H, Wheeler AR. All-in-One digital microfluidics pipeline for proteomic sample preparation and analysis. Chem Sci 2023; 14:2887-2900. [PMID: 36937585 PMCID: PMC10016607 DOI: 10.1039/d3sc00560g] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2023] [Accepted: 02/07/2023] [Indexed: 02/24/2023] Open
Abstract
Highly sensitive and reproducible analysis of samples containing low amounts of protein is restricted by sample loss and the introduction of contaminants during processing. Here, we report an All-in-One digital microfluidic (DMF) pipeline for proteomic sample reduction, alkylation, digestion, isotopic labeling and analysis. The system features end-to-end automation, with integrated thermal control for digestion, optimized droplet additives for sample manipulation and analysis, and an automated interface to liquid chromatography with tandem mass spectrometry (HPLC-MS/MS). Dimethyl labeling was integrated into the pipeline to allow for relative quantification of the trace samples at the nanogram level, and the new pipeline was applied to evaluating cancer cell lines and cancer tissue samples. Several known proteins (including HSP90AB1, HSPB1, LDHA, ENO1, PGK1, KRT18, and AKR1C2) and pathways were observed between model breast cancer cell lines related to hormone response, cell metabolism, and cell morphology. Furthermore, differentially quantified proteins (such as PGS2, UGDH, ASPN, LUM, COEA1, and PRELP) were found in comparisons of healthy and cancer breast tissues, suggesting potential utility of the All-in-One pipeline for the emerging application of proteomic cancer sub-typing. In sum, the All-in-One pipeline represents a powerful new tool for automated proteome processing and analysis, with the potential to be useful for evaluating mass-limited samples for a wide range of applications.
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Affiliation(s)
- Jiaxi Peng
- Department of Chemistry, University of Toronto 80 St. George Street Toronto ON M5S 3H6 Canada +1-416-946-3865 +1-416-946-3866
- Donnelly Centre for Cellular and Biomolecular Research, University of Toronto 160 College Street Toronto ON M5S 3E1 Canada
- Institute of Biomedical Engineering, University of Toronto 164 College Street Toronto ON M5S 3G9 Canada
| | - Calvin Chan
- Department of Chemistry, University of Toronto 80 St. George Street Toronto ON M5S 3H6 Canada +1-416-946-3865 +1-416-946-3866
| | - Shuailong Zhang
- Department of Chemistry, University of Toronto 80 St. George Street Toronto ON M5S 3H6 Canada +1-416-946-3865 +1-416-946-3866
- School of Mechatronical Engineering, Beijing Institute of Technology Beijing 100081 China
- Beijing Advanced Innovation Center for Intelligent Robots and Systems, Beijing Institute of Technology Beijing 100081 China
| | - Alexandros A Sklavounos
- Department of Chemistry, University of Toronto 80 St. George Street Toronto ON M5S 3H6 Canada +1-416-946-3865 +1-416-946-3866
- Donnelly Centre for Cellular and Biomolecular Research, University of Toronto 160 College Street Toronto ON M5S 3E1 Canada
| | - Maxwell E Olson
- Department of Chemistry, University of Toronto 80 St. George Street Toronto ON M5S 3H6 Canada +1-416-946-3865 +1-416-946-3866
| | - Erica Y Scott
- Department of Chemistry, University of Toronto 80 St. George Street Toronto ON M5S 3H6 Canada +1-416-946-3865 +1-416-946-3866
- Donnelly Centre for Cellular and Biomolecular Research, University of Toronto 160 College Street Toronto ON M5S 3E1 Canada
- Institute of Biomedical Engineering, University of Toronto 164 College Street Toronto ON M5S 3G9 Canada
| | - Yechen Hu
- Department of Chemistry, University of Toronto 80 St. George Street Toronto ON M5S 3H6 Canada +1-416-946-3865 +1-416-946-3866
- Donnelly Centre for Cellular and Biomolecular Research, University of Toronto 160 College Street Toronto ON M5S 3E1 Canada
- Institute of Biomedical Engineering, University of Toronto 164 College Street Toronto ON M5S 3G9 Canada
| | - Vigneshwar Rajesh
- Department of Chemistry, University of Toronto 80 St. George Street Toronto ON M5S 3H6 Canada +1-416-946-3865 +1-416-946-3866
| | - Bingyu B Li
- Donnelly Centre for Cellular and Biomolecular Research, University of Toronto 160 College Street Toronto ON M5S 3E1 Canada
- Institute of Biomedical Engineering, University of Toronto 164 College Street Toronto ON M5S 3G9 Canada
| | - M Dean Chamberlain
- Department of Chemistry, University of Toronto 80 St. George Street Toronto ON M5S 3H6 Canada +1-416-946-3865 +1-416-946-3866
- Donnelly Centre for Cellular and Biomolecular Research, University of Toronto 160 College Street Toronto ON M5S 3E1 Canada
- Institute of Biomedical Engineering, University of Toronto 164 College Street Toronto ON M5S 3G9 Canada
- Saskatchewan Cancer Agency, University of Saskatchewan 107 Wiggins Road Saskatoon SK S7N 5E5 Canada
| | - Shen Zhang
- Lunenfeld-Tanenbaum Research Institute, Mount Sinai Hospital 600 University Avenue Toronto ON M5G 1X5 Canada
- Clinical Research Center for Reproduction and Genetics in Hunan Province, Reproductive and Genetic Hospital of CITIC-XIANGYA Changsha Hunan 410000 China
| | - Hui Peng
- Department of Chemistry, University of Toronto 80 St. George Street Toronto ON M5S 3H6 Canada +1-416-946-3865 +1-416-946-3866
- School of Environment, University of Toronto 33 Willcocks Street Toronto ON M5S 3E8 Canada
| | - Aaron R Wheeler
- Department of Chemistry, University of Toronto 80 St. George Street Toronto ON M5S 3H6 Canada +1-416-946-3865 +1-416-946-3866
- Donnelly Centre for Cellular and Biomolecular Research, University of Toronto 160 College Street Toronto ON M5S 3E1 Canada
- Institute of Biomedical Engineering, University of Toronto 164 College Street Toronto ON M5S 3G9 Canada
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7
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Xu X, Cai L, Liang S, Zhang Q, Lin S, Li M, Yang Q, Li C, Han Z, Yang C. Digital microfluidics for biological analysis and applications. LAB ON A CHIP 2023; 23:1169-1191. [PMID: 36644972 DOI: 10.1039/d2lc00756h] [Citation(s) in RCA: 9] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/17/2023]
Abstract
Digital microfluidics (DMF) is an emerging liquid-handling technology based on arrays of microelectrodes for the precise manipulation of discrete droplets. DMF offers the benefits of automation, addressability, integration and dynamic configuration ability, and provides enclosed picoliter-to-microliter reaction space, making it suitable for lab-on-a-chip biological analysis and applications that require high integration and intricate processes. A review of DMF bioassays with a special emphasis on those actuated by electrowetting on dielectric (EWOD) force is presented here. Firstly, a brief introduction is presented on both the theory of EWOD actuation and the types of droplet motion. Subsequently, a comprehensive overview of DMF-based biological analysis and applications, including nucleic acid, protein, immunoreaction and cell assays, is provided. Finally, a discussion on the strengths, challenges, and potential applications and perspectives in this field is presented.
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Affiliation(s)
- Xing Xu
- The MOE Key Laboratory of Spectrochemical Analysis & Instrumentation, The Key Laboratory of Chemical Biology of Fujian Province, State Key Laboratory of Physical Chemistry of Solid Surfaces, Collaborative Innovation Center of Chemistry for Energy Materials, Department of Chemical Biology, Department of Chemical Engineering, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen 361005, China.
| | - Linfeng Cai
- The MOE Key Laboratory of Spectrochemical Analysis & Instrumentation, The Key Laboratory of Chemical Biology of Fujian Province, State Key Laboratory of Physical Chemistry of Solid Surfaces, Collaborative Innovation Center of Chemistry for Energy Materials, Department of Chemical Biology, Department of Chemical Engineering, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen 361005, China.
| | - Shanshan Liang
- The MOE Key Laboratory of Spectrochemical Analysis & Instrumentation, The Key Laboratory of Chemical Biology of Fujian Province, State Key Laboratory of Physical Chemistry of Solid Surfaces, Collaborative Innovation Center of Chemistry for Energy Materials, Department of Chemical Biology, Department of Chemical Engineering, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen 361005, China.
| | - Qiannan Zhang
- The MOE Key Laboratory of Spectrochemical Analysis & Instrumentation, The Key Laboratory of Chemical Biology of Fujian Province, State Key Laboratory of Physical Chemistry of Solid Surfaces, Collaborative Innovation Center of Chemistry for Energy Materials, Department of Chemical Biology, Department of Chemical Engineering, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen 361005, China.
| | - Shiyan Lin
- The MOE Key Laboratory of Spectrochemical Analysis & Instrumentation, The Key Laboratory of Chemical Biology of Fujian Province, State Key Laboratory of Physical Chemistry of Solid Surfaces, Collaborative Innovation Center of Chemistry for Energy Materials, Department of Chemical Biology, Department of Chemical Engineering, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen 361005, China.
| | - Mingying Li
- The MOE Key Laboratory of Spectrochemical Analysis & Instrumentation, The Key Laboratory of Chemical Biology of Fujian Province, State Key Laboratory of Physical Chemistry of Solid Surfaces, Collaborative Innovation Center of Chemistry for Energy Materials, Department of Chemical Biology, Department of Chemical Engineering, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen 361005, China.
| | - Qizheng Yang
- The MOE Key Laboratory of Spectrochemical Analysis & Instrumentation, The Key Laboratory of Chemical Biology of Fujian Province, State Key Laboratory of Physical Chemistry of Solid Surfaces, Collaborative Innovation Center of Chemistry for Energy Materials, Department of Chemical Biology, Department of Chemical Engineering, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen 361005, China.
| | - Chong Li
- The MOE Key Laboratory of Spectrochemical Analysis & Instrumentation, The Key Laboratory of Chemical Biology of Fujian Province, State Key Laboratory of Physical Chemistry of Solid Surfaces, Collaborative Innovation Center of Chemistry for Energy Materials, Department of Chemical Biology, Department of Chemical Engineering, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen 361005, China.
| | - Ziyan Han
- The MOE Key Laboratory of Spectrochemical Analysis & Instrumentation, The Key Laboratory of Chemical Biology of Fujian Province, State Key Laboratory of Physical Chemistry of Solid Surfaces, Collaborative Innovation Center of Chemistry for Energy Materials, Department of Chemical Biology, Department of Chemical Engineering, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen 361005, China.
| | - Chaoyong Yang
- The MOE Key Laboratory of Spectrochemical Analysis & Instrumentation, The Key Laboratory of Chemical Biology of Fujian Province, State Key Laboratory of Physical Chemistry of Solid Surfaces, Collaborative Innovation Center of Chemistry for Energy Materials, Department of Chemical Biology, Department of Chemical Engineering, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen 361005, China.
- Institute of Molecular Medicine, Renji Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, 200127, China
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8
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Ho M, Au A, Flick R, Vuong TV, Sklavounos AA, Swyer I, Yip CM, Wheeler AR. Antifouling Properties of Pluronic and Tetronic Surfactants in Digital Microfluidics. ACS APPLIED MATERIALS & INTERFACES 2023; 15:6326-6337. [PMID: 36696478 DOI: 10.1021/acsami.2c17317] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/17/2023]
Abstract
Fouling at liquid-solid interfaces is a pernicious problem for a wide range of applications, including those that are implemented by digital microfluidics (DMF). There are several strategies that have been used to combat surface fouling in DMF, the most common being inclusion of amphiphilic surfactant additives in the droplets to be manipulated. Initial studies relied on Pluronic additives, and more recently, Tetronic additives have been used, which has allowed manipulation of complex samples like serum and whole blood. Here, we report our evaluation of 19 different Pluronic and Tetronic additives, with attempts to determine (1) the difference in antifouling performance between the two families, (2) the structural similarities that predict exceptional antifouling performance, and (3) the mechanism of the antifouling behavior. Our analysis shows that both Pluronic and Tetronic additives with modest molar mass, poly(propylene oxide) (PPO) ≥50 units, poly(ethylene oxide) (PEO) mass percentage ≤50%, and hydrophilic-lipophilic balance (HLB) ca. 13-15 allow for exceptional antifouling performance in DMF. The most promising candidates, P104, P105, and T904, were able to support continuous movement of droplets of serum for more than 2 h, a result (for devices operating in air) previously thought to be out of reach for this technique. Additional results generated using device longevity assays, intrinsic fluorescence measurements, dynamic light scattering, asymmetric flow field flow fractionation, supercritical angle fluorescence microscopy, atomic force microscopy, and quartz crystal microbalance measurements suggest that the best-performing surfactants are more likely to operate by forming a protective layer at the liquid-solid interface than by complexation with proteins. We propose that these results and their implications are an important step forward for the growing community of users of this technique, which may provide guidance in selecting surfactants for manipulating biological matrices for a wide range of applications.
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Affiliation(s)
- Man Ho
- Department of Chemistry, University of Toronto, 80. St. George Street, Toronto, Ontario M5S 3H6, Canada
- Donnelly Centre for Cellular and Biomolecular Research, University of Toronto, 160 College Street, Toronto, Ontario M5S 3E1, Canada
| | - Aaron Au
- Donnelly Centre for Cellular and Biomolecular Research, University of Toronto, 160 College Street, Toronto, Ontario M5S 3E1, Canada
- Institute of Biomedical Engineering, University of Toronto, 164 College Street, Toronto, Ontario M5S 3G9, Canada
| | - Robert Flick
- Department of Chemical Engineering & Applied Chemistry, University of Toronto, 200 College Street, Toronto, Ontario M5S 3E5, Canada
| | - Thu V Vuong
- Department of Chemical Engineering & Applied Chemistry, University of Toronto, 200 College Street, Toronto, Ontario M5S 3E5, Canada
| | - Alexandros A Sklavounos
- Department of Chemistry, University of Toronto, 80. St. George Street, Toronto, Ontario M5S 3H6, Canada
- Donnelly Centre for Cellular and Biomolecular Research, University of Toronto, 160 College Street, Toronto, Ontario M5S 3E1, Canada
| | - Ian Swyer
- Department of Chemistry, University of Toronto, 80. St. George Street, Toronto, Ontario M5S 3H6, Canada
| | - Christopher M Yip
- Donnelly Centre for Cellular and Biomolecular Research, University of Toronto, 160 College Street, Toronto, Ontario M5S 3E1, Canada
- Institute of Biomedical Engineering, University of Toronto, 164 College Street, Toronto, Ontario M5S 3G9, Canada
- Department of Chemical Engineering & Applied Chemistry, University of Toronto, 200 College Street, Toronto, Ontario M5S 3E5, Canada
- Department of Biochemistry, University of Toronto, 1 King's College Circle, Toronto, Ontario M5S 1A8, Canada
| | - Aaron R Wheeler
- Department of Chemistry, University of Toronto, 80. St. George Street, Toronto, Ontario M5S 3H6, Canada
- Donnelly Centre for Cellular and Biomolecular Research, University of Toronto, 160 College Street, Toronto, Ontario M5S 3E1, Canada
- Institute of Biomedical Engineering, University of Toronto, 164 College Street, Toronto, Ontario M5S 3G9, Canada
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9
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Au A, Ho M, Wheeler AR, Yip CM. Monitoring non-specific adsorption at solid-liquid interfaces by supercritical angle fluorescence microscopy. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2022; 93:113707. [PMID: 36461515 DOI: 10.1063/5.0111787] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/19/2022] [Accepted: 10/12/2022] [Indexed: 06/17/2023]
Abstract
Supercritical angle fluorescence (SAF) microscopy is a novel imaging tool based on the use of distance-dependent fluorophore emission patterns to provide accurate locations of fluorophores relative to a surface. This technique has been extensively used to construct accurate cellular images and to detect surface phenomena in a static environment. However, the capability of SAF microscopy in monitoring dynamic surface phenomena and changes in millisecond intervals is underexplored in the literature. Here, we report on a hardware add-on for a conventional inverted microscope coupled with a post-processing Python module that extends the capability of SAF microscopy to monitor dynamic surface adsorption in sub-second intervals, thereby greatly expanding the potential of this tool to study surface interactions, such as surface fouling and competitive surface adhesion. The Python module enables researchers to automatically extract SAF profiles from each image. We first assessed the performance of the system by probing the specific binding of biotin-fluorescein conjugates to a neutravidin-coated cover glass in the presence of non-binding fluorescein. The SAF emission was observed to increase with the quantity of bound fluorophore on the cover glass. However, a high concentration of unbound fluorophore also contributed to overall SAF emission, leading to over-estimation in surface-bound fluorescence. To expand the applications of SAF in monitoring surface phenomena, we monitored the non-specific surface adsorption of BSA and non-ionic surfactants on a Teflon-AF surface. Solution mixtures of bovine serum albumin (BSA) and nine Pluronic/Tetronic surfactants were exposed to a Teflon-AF surface. No significant BSA adsorption was observed in all BSA-surfactant solution mixtures with negligible SAF intensity. Finally, we monitored the adsorption dynamics of BSA onto the Teflon-AF surface and observed rapid BSA adsorption on Teflon-AF surface within 10 s of addition. The adsorption rate constant (ka) and half-life of BSA adsorption on Teflon-AF were determined to be 0.419 ± 0.004 s-1 and 1.65 ± 0.016 s, respectively, using a pseudo-first-order adsorption equation.
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Affiliation(s)
- Aaron Au
- Institute for Biomedical Engineering, University of Toronto, 164 College Street, Toronto, Ontario M5S 3G9, Canada
| | - Man Ho
- Donnelly Centre for Cellular and Biomolecular Research, University of Toronto, 160 College Street, Toronto, Ontario M5S 3E1, Canada
| | - Aaron R Wheeler
- Donnelly Centre for Cellular and Biomolecular Research, University of Toronto, 160 College Street, Toronto, Ontario M5S 3E1, Canada
| | - Christopher M Yip
- Institute for Biomedical Engineering, University of Toronto, 164 College Street, Toronto, Ontario M5S 3G9, Canada
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10
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Steinbach MK, Leipert J, Blurton C, Leippe M, Tholey A. Digital Microfluidics Supported Microproteomics for Quantitative Proteome Analysis of Single Caenorhabditis elegans Nematodes. J Proteome Res 2022; 21:1986-1996. [PMID: 35771142 DOI: 10.1021/acs.jproteome.2c00274] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Miniaturization of sample preparation, including omissible manual sample handling steps, is key for reproducible nanoproteomics, as material is often restricted to only hundreds of cells or single model organisms. Here, we demonstrate a highly sensitive digital microfluidics (DMF)-based sample preparation workflow making use of single-pot solid-phase enhanced sample preparation (SP3) in combination with high-field asymmetric-waveform ion mobility spectrometry (FAIMS), and fast and sensitive ion trap detection on an Orbitrap tribrid MS system. Compared to a manual in-tube SP3-supported sample preparation, the numbers of identified peptides and proteins were markedly increased, while lower standard deviations between replicates were observed. We repeatedly identified up to 5000 proteins from single nematodes. Moreover, label-free quantification of protein changes in single Caenorhabditis elegans treated with a heat stimulus yielded 45 differentially abundant proteins when compared to the untreated control, highlighting the potential of this technology for low-input proteomics studies. LC-MS data have been deposited to the ProteomeXchange Consortium with the data set identifier PXD033143.
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Affiliation(s)
- Max K Steinbach
- Systematic Proteome Research & Bioanalytics, Institute for Experimental Medicine, Christian-Albrechts-Universität zu Kiel, 24105 Kiel, Germany
| | - Jan Leipert
- Systematic Proteome Research & Bioanalytics, Institute for Experimental Medicine, Christian-Albrechts-Universität zu Kiel, 24105 Kiel, Germany
| | - Christine Blurton
- Comparative Immunobiology, Zoological Institute, Christian-Albrechts-Universität zu Kiel, 24098 Kiel, Germany
| | - Matthias Leippe
- Comparative Immunobiology, Zoological Institute, Christian-Albrechts-Universität zu Kiel, 24098 Kiel, Germany
| | - Andreas Tholey
- Systematic Proteome Research & Bioanalytics, Institute for Experimental Medicine, Christian-Albrechts-Universität zu Kiel, 24105 Kiel, Germany
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11
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Karcz A, Van Soom A, Smits K, Verplancke R, Van Vlierberghe S, Vanfleteren J. Electrically-driven handling of gametes and embryos: taking a step towards the future of ARTs. LAB ON A CHIP 2022; 22:1852-1875. [PMID: 35510672 DOI: 10.1039/d1lc01160j] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
Electrical stimulation of gametes and embryos and on-chip manipulation of microdroplets of culture medium serve as promising tools for assisted reproductive technologies (ARTs). Thus far, dielectrophoresis (DEP), electrorotation (ER) and electrowetting on dielectric (EWOD) proved compatible with most laboratory procedures offered by ARTs. Positioning, entrapment and selection of reproductive cells can be achieved with DEP and ER, while EWOD provides the dynamic microenvironment of a developing embryo to better mimic the functions of the oviduct. Furthermore, these techniques are applicable for the assessment of the developmental competence of a mammalian embryo in vitro. Such research paves the way towards the amelioration and full automation of the assisted reproduction methods. This article aims to provide a summary on the recent developments regarding electrically stimulated lab-on-chip devices and their application for the manipulation of gametes and embryos in vitro.
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Affiliation(s)
- Adriana Karcz
- Centre for Microsystems Technology (CMST), Imec and Ghent University, Technologiepark Zwijnaarde 126, 9052 Zwijnaarde, Ghent, Belgium.
- Reproductive Biology Unit (RBU), Faculty of Veterinary Medicine, Department of Internal Medicine, Reproduction and Population Medicine, Ghent University, Salisburylaan 133 D4 entrance 4, 9820 Merelbeke, Belgium
| | - Ann Van Soom
- Reproductive Biology Unit (RBU), Faculty of Veterinary Medicine, Department of Internal Medicine, Reproduction and Population Medicine, Ghent University, Salisburylaan 133 D4 entrance 4, 9820 Merelbeke, Belgium
| | - Katrien Smits
- Reproductive Biology Unit (RBU), Faculty of Veterinary Medicine, Department of Internal Medicine, Reproduction and Population Medicine, Ghent University, Salisburylaan 133 D4 entrance 4, 9820 Merelbeke, Belgium
| | - Rik Verplancke
- Centre for Microsystems Technology (CMST), Imec and Ghent University, Technologiepark Zwijnaarde 126, 9052 Zwijnaarde, Ghent, Belgium.
| | - Sandra Van Vlierberghe
- Polymer Chemistry and Biomaterials Group, Centre of Macromolecular Chemistry, Ghent University, Campus Sterre, building S4, Krijgslaan 281, 9000 Ghent, Belgium
| | - Jan Vanfleteren
- Centre for Microsystems Technology (CMST), Imec and Ghent University, Technologiepark Zwijnaarde 126, 9052 Zwijnaarde, Ghent, Belgium.
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12
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Sun Z, Lin KF, Zhao ZH, Wang Y, Hong XX, Guo JG, Ruan QY, Lu LY, Li X, Zhang R, Yang CY, Li BA. An automated nucleic acid detection platform using digital microfluidics with an optimized Cas12a system. Sci China Chem 2022; 65:630-640. [PMID: 35126481 PMCID: PMC8809245 DOI: 10.1007/s11426-021-1169-1] [Citation(s) in RCA: 16] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2021] [Accepted: 11/26/2021] [Indexed: 12/26/2022]
Abstract
Outbreaks of both influenza virus and the novel coronavirus SARS-CoV-2 are serious threats to human health and life. It is very important to establish a rapid, accurate test with large-scale detection potential to prevent the further spread of the epidemic. An optimized RPA-Cas12a-based platform combined with digital microfluidics (DMF), the RCD platform, was established to achieve the automated, rapid detection of influenza viruses and SARS-CoV-2. The probe in the RPA-Cas12a system was optimized to produce maximal fluorescence to increase the amplification signal. The reaction droplets in the platform were all at the microliter level and the detection could be accomplished within 30 min due to the effective mixing of droplets by digital microfluidic technology. The whole process from amplification to recognition is completed in the chip, which reduces the risk of aerosol contamination. One chip can contain multiple detection reaction areas, offering the potential for customized detection. The RCD platform demonstrated a high level of sensitivity, specificity (no false positives or negatives), speed (≤30 min), automation and multiplexing. We also used the RCD platform to detect nucleic acids from influenza patients and COVID-19 patients. The results were consistent with the findings of qPCR. The RCD platform is a one-step, rapid, highly sensitive and specific method with the advantages of digital microfluidic technology, which circumvents the shortcomings of manual operation. The development of the RCD platform provides potential for the isothermal automatic detection of nucleic acids during epidemics.
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Affiliation(s)
- Zhen Sun
- State Key Laboratory of Cellular Stress Biology, Innovation Center for Cell Signaling Network and Engineering Research Center of Molecular Diagnostics of the Ministry of Education, School of Life Sciences, Xiamen University, Xiamen, 361005 China
| | - Kang-Feng Lin
- State Key Laboratory of Cellular Stress Biology, Innovation Center for Cell Signaling Network and Engineering Research Center of Molecular Diagnostics of the Ministry of Education, School of Life Sciences, Xiamen University, Xiamen, 361005 China
| | - Ze-Hang Zhao
- State Key Laboratory of Cellular Stress Biology, Innovation Center for Cell Signaling Network and Engineering Research Center of Molecular Diagnostics of the Ministry of Education, School of Life Sciences, Xiamen University, Xiamen, 361005 China
| | - Yang Wang
- MOE Key Laboratory of Spectrochemical Analysis & Instrumentation, Key Laboratory of Chemical Biology of Fujian Province, State Key Laboratory of Physical Chemistry of Solid Surfaces, Collaborative Innovation Center of Chemistry for Energy Materials, Department of Chemical Engineering, Department of Chemical Biology, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen, 361005 China
| | - Xin-Xin Hong
- State Key Laboratory of Cellular Stress Biology, Innovation Center for Cell Signaling Network and Engineering Research Center of Molecular Diagnostics of the Ministry of Education, School of Life Sciences, Xiamen University, Xiamen, 361005 China
| | - Jian-Guang Guo
- State Key Laboratory of Cellular Stress Biology, Innovation Center for Cell Signaling Network and Engineering Research Center of Molecular Diagnostics of the Ministry of Education, School of Life Sciences, Xiamen University, Xiamen, 361005 China
| | - Qing-Yu Ruan
- MOE Key Laboratory of Spectrochemical Analysis & Instrumentation, Key Laboratory of Chemical Biology of Fujian Province, State Key Laboratory of Physical Chemistry of Solid Surfaces, Collaborative Innovation Center of Chemistry for Energy Materials, Department of Chemical Engineering, Department of Chemical Biology, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen, 361005 China
| | - Lian-Yu Lu
- MOE Key Laboratory of Spectrochemical Analysis & Instrumentation, Key Laboratory of Chemical Biology of Fujian Province, State Key Laboratory of Physical Chemistry of Solid Surfaces, Collaborative Innovation Center of Chemistry for Energy Materials, Department of Chemical Engineering, Department of Chemical Biology, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen, 361005 China
| | - Xiao Li
- State Key Laboratory of Cellular Stress Biology, Innovation Center for Cell Signaling Network and Engineering Research Center of Molecular Diagnostics of the Ministry of Education, School of Life Sciences, Xiamen University, Xiamen, 361005 China
| | - Rui Zhang
- Department of Thoracic Surgery, The First Affiliated Hospital, Xiamen University, Xiamen, 361005 China
| | - Chao-Yong Yang
- MOE Key Laboratory of Spectrochemical Analysis & Instrumentation, Key Laboratory of Chemical Biology of Fujian Province, State Key Laboratory of Physical Chemistry of Solid Surfaces, Collaborative Innovation Center of Chemistry for Energy Materials, Department of Chemical Engineering, Department of Chemical Biology, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen, 361005 China
| | - Bo-An Li
- State Key Laboratory of Cellular Stress Biology, Innovation Center for Cell Signaling Network and Engineering Research Center of Molecular Diagnostics of the Ministry of Education, School of Life Sciences, Xiamen University, Xiamen, 361005 China
- MOE Key Laboratory of Spectrochemical Analysis & Instrumentation, Key Laboratory of Chemical Biology of Fujian Province, State Key Laboratory of Physical Chemistry of Solid Surfaces, Collaborative Innovation Center of Chemistry for Energy Materials, Department of Chemical Engineering, Department of Chemical Biology, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen, 361005 China
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13
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Jin K, Hu C, Hu S, Hu C, Li J, Ma H. "One-to-three" droplet generation in digital microfluidics for parallel chemiluminescence immunoassays. LAB ON A CHIP 2021; 21:2892-2900. [PMID: 34196334 DOI: 10.1039/d1lc00421b] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
In digital microfluidics, droplet generation is a fundamental operation for quantitative liquid manipulation. The generation of well-defined micro-droplets on a chip with restricted device geometries has become a real obstacle for digital microfluidics platforms to be used in parallel for in vitro diagnostic applications. Here, we propose a "one-to-three" droplet splitting technique that is able to generate sub-microlitre droplets beyond the "well-known" geometry limit in electrowetting-on-dielectric digital microfluidics. Accordingly, we realized an on-chip magnetic bead chemiluminescence immunoassay for parallel detection with the "one-to-three" technique. With the help of the generated micro droplets, we were able to retain the magnetic beads by a significantly reduced magnetic force. We have shown the detection of five B-type natriuretic peptide analyte samples on a single chip for around 10 minutes. The correlation coefficient of the calibration curve was 0.9942, and the detection limit was lower than 5 pg mL-1.
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Affiliation(s)
- Kai Jin
- Ministry of Education Key Laboratory for Cross-Scale Micro and Nano Manufacturing, Nanophotonics and Biophotonics Key Laboratory of Jilin Province, School of Science, Changchun University of Science and Technology, Changchun, Jilin province 130022, P.R.China. and CAS Key Laboratory of Bio-medical Diagnostics, Suzhou Institute of Biomedical Engineering and Technology, Chinese Academy of Sciences, No. 88 Keling Road, Suzhou, Jiangsu province 215163, P.R.China.
| | - Chenxuan Hu
- CAS Key Laboratory of Bio-medical Diagnostics, Suzhou Institute of Biomedical Engineering and Technology, Chinese Academy of Sciences, No. 88 Keling Road, Suzhou, Jiangsu province 215163, P.R.China.
| | - Siyi Hu
- CAS Key Laboratory of Bio-medical Diagnostics, Suzhou Institute of Biomedical Engineering and Technology, Chinese Academy of Sciences, No. 88 Keling Road, Suzhou, Jiangsu province 215163, P.R.China.
| | - Chengyou Hu
- Guangdong ACXEL Micro & Nano Tech Co., Ltd, Guangdong province 528000, P.R.China
| | - Jinhua Li
- Ministry of Education Key Laboratory for Cross-Scale Micro and Nano Manufacturing, Nanophotonics and Biophotonics Key Laboratory of Jilin Province, School of Science, Changchun University of Science and Technology, Changchun, Jilin province 130022, P.R.China.
| | - Hanbin Ma
- CAS Key Laboratory of Bio-medical Diagnostics, Suzhou Institute of Biomedical Engineering and Technology, Chinese Academy of Sciences, No. 88 Keling Road, Suzhou, Jiangsu province 215163, P.R.China.
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14
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Design of ophthalmic micelles loaded with diclofenac sodium: effect of chitosan and temperature on the block-copolymer micellization behaviour. Drug Deliv Transl Res 2021; 12:1488-1507. [PMID: 34258717 DOI: 10.1007/s13346-021-01030-4] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 07/04/2021] [Indexed: 10/20/2022]
Abstract
Diclofenac sodium 0.1% is a commonly used NSAID with well-documented clinical efficacy in reducing postoperative inflammation; however, its corneal tolerability and ophthalmic tissue bioavailability require further improvement. Advanced micellar delivery systems composed of block-copolymers and chitosan showing fine balance between the mucoadhesion and mucus permeation, capable to slip through the mucus barrier and adhere to the epithelial ocular surface, may be used to tackle both challenges. The aggregation behaviour of the block-copolymers in the presence of different additives will dramatically influence the quality attributes like particle size, particle size distribution, drug-polymer interaction, zeta potential, drug incorporation, important for the delicate balance among mucoadhesion and permeation, as well as safety and efficacy of the ophthalmic micelles. Therefore, quality by design approach and D-optimal experimental design model were used to create a pool of useful data for the influence of chitosan and the formulation factors on the block copolymer's aggregation behaviour during the development and optimization of Diclofenac loaded Chitosan/Lutrol F127 or F68 micelles. Particle size, polydispersity index, dissolution rate, FTIR and DSC studies, NMR spectroscopy, cytotoxicity, mucoadhesivity, mucus permeation studies, and bioadhesivity were assessed as critical quality attributes. FTIR and DSC studies pointed to the chaotropic effect of chitosan during the micelle aggregation. Mainly, Pluronic F68 micellization behaviour was more dramatically affected by the presence of chitosan, and self-aggregation into larger micelles with high polydispersity index was favoured at higher chitosan concentration. The optimized formulation with highest potential for ophthalmic delivery of diclofenac sodium, good cytotoxicity profile, delicate balance of the mucoadhesivity, and mucus permeation was in the design space of Chitosan/Lutrol F127 micelles.
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15
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Leipert J, Steinbach MK, Tholey A. Isobaric Peptide Labeling on Digital Microfluidics for Quantitative Low Cell Number Proteomics. Anal Chem 2021; 93:6278-6286. [PMID: 33823593 DOI: 10.1021/acs.analchem.1c01205] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Digital microfluidics (DMF) is a technology suitable for bioanalytical applications requiring miniaturized, automated, and multiplexed liquid handling. Its use in LC-MS-based proteomics, however, has so far been limited to qualitative proteome analyses. This is mainly due to the need for detergents that enable facile, reproducible droplet movement, which are compatible with organic solvents commonly used in targeted chemical modifications of peptides. Aiming to implement isobaric peptide labeling, a widely applied technique allowing multiplexed quantitative proteome studies, on DMF devices, we tested different commercially available detergents. We identified the maltoside-based detergent 3-dodecyloxypropyl-1-β-d-maltopyranoside (DDOPM) to enable facile droplet movement and show micelle formation even in the presence of organic solvent, which is necessary for isobaric tandem mass tag (TMT) labeling. The detergent is fully compatible with reversed phase LC-MS, not interfering with peptide identification. Tryptic digestion in the presence of DDOPM was more efficient than without detergent, resulting in more protein identifications. Using this detergent, we report the first on-DMF chip isobaric labeling strategy, with TMT-labeling efficiency comparable to conventional protocols. The newly developed labeling protocol was evaluated in the multiplexed analyses of a protein standard digest spiked into 25 cells. Finally, using only 75 cells per biological replicate, we were able to identify 39 proteins being differentially abundant after treatment of Jurkat T cells with the anticancer drug doxorubicin. In summary, we demonstrate an important step toward multiplexed quantitative proteomics on DMF, which, in combination with larger chip arrays and optimized hardware, could enable high throughput low cell number proteomics.
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Affiliation(s)
- Jan Leipert
- Systematic Proteome Research & Bioanalytics, Institute for Experimental Medicine, Christian-Albrechts-Universität zu Kiel, Kiel 24105, Germany
| | - Max K Steinbach
- Systematic Proteome Research & Bioanalytics, Institute for Experimental Medicine, Christian-Albrechts-Universität zu Kiel, Kiel 24105, Germany
| | - Andreas Tholey
- Systematic Proteome Research & Bioanalytics, Institute for Experimental Medicine, Christian-Albrechts-Universität zu Kiel, Kiel 24105, Germany
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16
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Heine V, Kremers T, Menzel N, Schnakenberg U, Elling L. Electrochemical Impedance Spectroscopy Biosensor Enabling Kinetic Monitoring of Fucosyltransferase Activity. ACS Sens 2021; 6:1003-1011. [PMID: 33595293 DOI: 10.1021/acssensors.0c02206] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Monitoring glycosyltransferases on biosensors is of great interest for pathogen and cancer diagnostics. As a proof of concept, we here demonstrate the layer-by-layer immobilization of a multivalent neoglycoprotein (NGP) as a substrate for a bacterial fucosyltransferase (FucT) and the subsequent binding of the fucose-specific Aleuria aurantia lectin (AAL) on an electrochemical impedance spectroscopy (EIS) sensor. We report for the first time the binding kinetics of a glycosyltransferase in real-time. Highly stable EIS measurements are obtained by the modification of counter and reference electrodes with polypyrrole: polystyrene sulfonate (PPy:PSS). In detail, the N-acetyllactosamine (LacNAc)-carrying NGP was covalently immobilized on the gold working electrode and served as a substrate for the FucT-catalyzed reaction. The LacNAc epitopes were converted to Lewisx (Lex) and detected by AAL. AAL binding to the Lex epitope was further confirmed in a lectin displacement and a competitive lectin binding inhibition experiment. We monitored the individual kinetic processes via EIS. The time constant for covalent immobilization of the NGP was 653 s. The FucT kinetics was the slowest process with a time constant of 1121 s. In contrast, a short time constant of 11.8 s was determined for the interaction of AAL with the modified NGPs. When this process was competed by 400 mM fucose, the binding was significantly slowed down, as indicated by a time constant of 978 s. The kinetics for the displacement of bound AAL by free fucose was observed with a time constant of 424 s. We conclude that this novel EIS biosensor and the applied workflow has the potential to detect FucT and other GT activities in general and further monitor protein-glycan interactions, which may be useful for the detection of pathogenic bacteria and cancer cells in future biomedical applications.
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Affiliation(s)
- Viktoria Heine
- Laboratory for Biomaterials, Institute for Biotechnology and Helmholtz-Institute for Biomedical Engineering, RWTH Aachen University, Pauwelsstraße 20, D-52074 Aachen, Germany
| | - Tom Kremers
- Chair of Micro- and Nanosystems and Institute of Materials in Electrical Engineering 1, RWTH Aachen University, Sommerfeldstraße 24, D-52074 Aachen, Germany
| | - Nora Menzel
- Laboratory for Biomaterials, Institute for Biotechnology and Helmholtz-Institute for Biomedical Engineering, RWTH Aachen University, Pauwelsstraße 20, D-52074 Aachen, Germany
- Chair of Micro- and Nanosystems and Institute of Materials in Electrical Engineering 1, RWTH Aachen University, Sommerfeldstraße 24, D-52074 Aachen, Germany
| | - Uwe Schnakenberg
- Chair of Micro- and Nanosystems and Institute of Materials in Electrical Engineering 1, RWTH Aachen University, Sommerfeldstraße 24, D-52074 Aachen, Germany
| | - Lothar Elling
- Laboratory for Biomaterials, Institute for Biotechnology and Helmholtz-Institute for Biomedical Engineering, RWTH Aachen University, Pauwelsstraße 20, D-52074 Aachen, Germany
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17
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Rui X, Song S, Wang W, Zhou J. Applications of electrowetting-on-dielectric (EWOD) technology for droplet digital PCR. BIOMICROFLUIDICS 2020; 14:061503. [PMID: 33312327 PMCID: PMC7719047 DOI: 10.1063/5.0021177] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/10/2020] [Accepted: 11/24/2020] [Indexed: 05/25/2023]
Abstract
Digital microfluidics is an elegant technique based on single droplets for the design, composition, and manipulation of microfluidic systems. In digital microfluidics, especially in the electrowetting on dielectric (EWOD) system, each droplet acts as an independent reactor, which enables a wide range of multiple parallel biological and chemical reactions at the microscale. EWOD digital microfluidics reduces reagent and energy consumption, accelerates analysis, enables point-of-care diagnostic, simplifies integration with sensors, etc. Such a digital microfluidic system is especially relevant for droplet digital PCR (ddPCR), thanks to its nanoliter droplets and well-controlled volume distribution. At low DNA concentration, these small volumes allow less than one DNA strand per droplet on average (limited dilution) so that after a fixed number of PCR cycles (endpoint PCR), only the DNA in droplets containing the sequence of interest has been amplified and can be detected by fluorescence to yield an accurate count of the sequences of interest using statistical models. Focusing on ddPCR, this article summarizes the latest development and research on EWOD technology for droplet PCR over the last decade.
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Affiliation(s)
| | | | | | - Jia Zhou
- Author to whom correspondence should be addressed:
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18
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Frey LJ, Vorländer D, Rasch D, Meinen S, Müller B, Mayr T, Dietzel A, Grosch JH, Krull R. Defining mass transfer in a capillary wave micro-bioreactor for dose-response and other cell-based assays. Biochem Eng J 2020. [DOI: 10.1016/j.bej.2020.107667] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
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19
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Kothamachu VB, Zaini S, Muffatto F. Role of Digital Microfluidics in Enabling Access to Laboratory Automation and Making Biology Programmable. SLAS Technol 2020; 25:411-426. [PMID: 32584152 DOI: 10.1177/2472630320931794] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Digital microfluidics (DMF) is a liquid handling technique that has been demonstrated to automate biological experimentation in a low-cost, rapid, and programmable manner. This review discusses the role of DMF as a "digital bioconverter"-a tool to connect the digital aspects of the design-build-learn cycle with the physical execution of experiments. Several applications are reviewed to demonstrate the utility of DMF as a digital bioconverter, namely, genetic engineering, sample preparation for sequencing and mass spectrometry, and enzyme-, immuno-, and cell-based screening assays. These applications show that DMF has great potential in the role of a centralized execution platform in a fully integrated pipeline for the production of novel organisms and biomolecules. In this paper, we discuss how the function of a DMF device within such a pipeline is highly dependent on integration with different sensing techniques and methodologies from machine learning and big data. In addition to that, we examine how the capacity of DMF can in some cases be limited by known technical and operational challenges and how consolidated efforts in overcoming these challenges will be key to the development of DMF as a major enabling technology in the computer-aided biology framework.
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20
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Leipert J, Tholey A. Miniaturized sample preparation on a digital microfluidics device for sensitive bottom-up microproteomics of mammalian cells using magnetic beads and mass spectrometry-compatible surfactants. LAB ON A CHIP 2019; 19:3490-3498. [PMID: 31531506 DOI: 10.1039/c9lc00715f] [Citation(s) in RCA: 32] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
While LC-MS-based proteomics with high nanograms to micrograms of total protein has become routine, the analysis of samples derived from low cell numbers is challenged by factors such as sample losses, or difficulties encountered with the manual manipulation of small liquid volumes. Digital microfluidics (DMF) is an emerging technique for miniaturized and automated droplet manipulation, which has been proposed as a promising tool for proteomic sample preparation. However, proteome analysis of samples prepared on-chip by DMF has previously been unfeasible, due to incompatibility with down-stream LC-MS instrumentation. To overcome these limitations, we here developed protocols for bottom-up LC-MS based proteomics sample preparation of as little as 100 mammalian cells on a commercially available digital microfluidics device. To this end, we developed effective cell lysis conditions optimized for DMF, as well as detergent-buffer systems compatible with downstream proteolytic digestion on DMF chips and subsequent LC-MS analysis. A major step was the introduction of the single-pot, solid-phase-enhanced sample preparation (SP3) approach on-chip, which allowed the removal of salts and anti-fouling polymeric detergents, thus rendering sample preparation by DMF compatible with LC-MS-based proteome analysis. Application of DMF-SP3 to the proteome analysis of Jurkat T cells led to the identification of up to 2500 proteins from approximately 500 cells, and up to 1200 proteins from approximately 100 cells on an Orbitrap mass spectrometer, emphasizing the high compatibility of DMF-SP3 with low protein input and minute volumes handled by DMF. Taken together, we demonstrate the first sample preparation workflow for proteomics on a DMF chip device reported so far, allowing the sensitive analysis of limited biological material.
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Affiliation(s)
- Jan Leipert
- Systematic Proteome Research & Bioanalytics, Institute for Experimental Medicine, Christian-Albrechts-Universität zu Kiel, 24105 Kiel, Germany.
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21
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Geng H, Cho SK. Antifouling digital microfluidics using lubricant infused porous film. LAB ON A CHIP 2019; 19:2275-2283. [PMID: 31184676 DOI: 10.1039/c9lc00289h] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
Electrowetting-driven digital (droplet-based) microfluidics has a tremendous impact on lab-on-a-chip applications. However, the biofouling problem impedes the real applications of such digital microfluidics. Here we report antifouling digital microfluidics by introducing lubricant infused porous film to electrowetting (more exactly, electrowetting on dielectric or EWOD). Such film minimizes direct contact between droplets and the solid surface but provides liquid-liquid contact between droplets and the lubricant liquid, which thus prevents unspecific adsorption of biomolecules to the solid surface. We demonstrate the compatibility of the lubricant infused film with EWOD to transport bio droplets. This configuration shows robust and high performance even for long cyclic operations without fouling in a wide range of concentrations of protein solutions. In addition, a variety of conductive droplets, including deionized (DI) water, saline, protein solution, DNA solution, sheep blood, milk, ionic liquid and honey, are examined, similarly showing high performance in cyclic transportations. In addition, using the same electrode patterns used in EWOD, transportations of dielectric (non-conductive) droplets including light crude oil, propylene carbonate and alcohol are also achieved. Such capability of droplet handling without fouling will certainly benefit the practical applications of digital microfluidics in droplet handling, sampling, reaction, diagnosis in clinic medicine, biotechnology and chemistry fields.
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Affiliation(s)
- Hongyao Geng
- Department of Mechanical Engineering and Materials Science, University of Pittsburgh, PA 15261, USA.
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22
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Leclerc LMY, Soffer G, Kwan DH, Shih SCC. A fucosyltransferase inhibition assay using image-analysis and digital microfluidics. BIOMICROFLUIDICS 2019; 13:034106. [PMID: 31123538 PMCID: PMC6510662 DOI: 10.1063/1.5088517] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/10/2019] [Accepted: 04/29/2019] [Indexed: 05/08/2023]
Abstract
Sialyl-LewisX and LewisX are cell-surface glycans that influence cell-cell adhesion behaviors. These glycans are assembled by α(1,3)-fucosyltransferase enzymes. Their increased expression plays a role in inflammatory disease, viral and microbial infections, and cancer. Efficient screens for specific glycan modifications such as those catalyzed by fucosyltransferases are tended toward costly materials and large instrumentation. We demonstrate for the first time a fucosylation inhibition assay on a digital microfluidic system with the integration of image-based techniques. Specifically, we report a novel lab-on-a-chip approach to perform a fluorescence-based inhibition assay for the fucosylation of a labeled synthetic disaccharide, 4-methylumbelliferyl β-N-acetyllactosaminide. As a proof-of-concept, guanosine 5'-diphosphate has been used to inhibit Helicobacter pylori α(1,3)-fucosyltransferase. An electrode shape (termed "skewed wave") is designed to minimize electrode density and improve droplet movement compared to conventional square-based electrodes. The device is used to generate a 10 000-fold serial dilution of the inhibitor and to perform fucosylation reactions in aqueous droplets surrounded by an oil shell. Using an image-based method of calculating dilutions, referred to as "pixel count," inhibition curves along with IC50 values are obtained on-device. We propose the combination of integrating image analysis and digital microfluidics is suitable for automating a wide range of enzymatic assays.
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Affiliation(s)
| | | | | | - Steve C. C. Shih
- Author to whom correspondence should be addressed:. Tel.: +1-(514)-848-2424x7579
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23
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Swyer I, Fobel R, Wheeler AR. Velocity Saturation in Digital Microfluidics. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2019; 35:5342-5352. [PMID: 30958677 DOI: 10.1021/acs.langmuir.9b00220] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
In digital microfluidics, discrete droplets of fluid are made to move on an open surface with no microchannels. These systems are commonly operated by application of electrical driving forces to an array of electrodes. While these driving forces are well characterized, the dissipative forces opposing droplet movement have not been as thoroughly examined. In recognition of this deficit, we used force-velocity plots to characterize droplet movement in digital microfluidics, which was found to be consistent with a simple theoretical framework for understanding dissipation effects for droplets in two-plate, air-filled devices. Interestingly, in some conditions, a previously unreported ″velocity saturation″ effect was observed. When examined across a range of different liquids, the forces at which this saturation occurs seem to be lower for liquids with smaller surface tensions. Furthermore, when driven at forces that cause saturation, physical phenomena are observed that are akin to what has been reported for stationary droplets in the electrowetting literature. These phenomena are detrimental to device performance, leading to a new "force window" approach that delineates the optimum operation conditions for different liquids. We propose that these findings may be useful for a wide range of applications for experts and new users alike in this growing field.
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Affiliation(s)
- Ian Swyer
- Department of Chemistry , University of Toronto , 80 St. George Street , Toronto , ON M5S 3H6 , Canada
| | - Ryan Fobel
- Donnelly Centre for Cellular and Biomolecular Research , University of Toronto , 160 College Street , Toronto , ON M5S 3E1 , Canada
| | - Aaron R Wheeler
- Department of Chemistry , University of Toronto , 80 St. George Street , Toronto , ON M5S 3H6 , Canada
- Donnelly Centre for Cellular and Biomolecular Research , University of Toronto , 160 College Street , Toronto , ON M5S 3E1 , Canada
- Institute for Biomaterials and Biomedical Engineering , University of Toronto , 164 College Street , Toronto , ON M5S 3G9 , Canada
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24
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Coudron L, McDonnell MB, Munro I, McCluskey DK, Johnston ID, Tan CK, Tracey MC. Fully integrated digital microfluidics platform for automated immunoassay; A versatile tool for rapid, specific detection of a wide range of pathogens. Biosens Bioelectron 2019; 128:52-60. [DOI: 10.1016/j.bios.2018.12.014] [Citation(s) in RCA: 42] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2018] [Revised: 11/29/2018] [Accepted: 12/11/2018] [Indexed: 11/17/2022]
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25
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Liu Y, Papautsky I. Heterogeneous Immunoassay Using Channels and Droplets in a Digital Microfluidic Platform. MICROMACHINES 2019; 10:mi10020107. [PMID: 30764575 PMCID: PMC6412725 DOI: 10.3390/mi10020107] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/15/2018] [Revised: 01/29/2019] [Accepted: 02/01/2019] [Indexed: 01/11/2023]
Abstract
This work presents a heterogeneous immunoassay using the integrated functionalities of a channel and droplets in a digital microfluidic (DMF) platform. Droplet functionality in DMF allows for the programmable manipulation of discrete sample and reagent droplets in the range of nanoliters. Pressure-driven channels become advantageous over droplets when sample must be washed, as the supernatant can be thoroughly removed in a convenient and rapid manner while the sample is immobilized. Herein, we demonstrate a magnetic bead-based, enzyme-linked immunosorbent assay (ELISA) using ~60 nL of human interleukin-6 (IL-6) sample. The wash buffer was introduced in the form of a wall-less virtual electrowetting channel by a syringe pump at the flow rate of 10 μL/min with ~100% bead retention rate. Critical parameters such as sample wash flow rate and bead retention rate were optimized for reliable assay results. A colorimetric readout was analyzed in the International Commission on Illumination (CIE) color space without the need for costly equipment. The concepts presented in this work are potentially applicable in rapid neonatal disease screening using a finger prick blood sample in a DMF platform.
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Affiliation(s)
- Yuguang Liu
- Microbiome Program, Center for Individualized Medicine, Mayo Clinic, Rochester, MN 55905, USA.
| | - Ian Papautsky
- Department of Bioengineering, University of Illinois at Chicago, Chicago, IL 60607, USA.
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26
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de Campos RPS, Rackus DG, Shih R, Zhao C, Liu X, Wheeler AR. “Plug-n-Play” Sensing with Digital Microfluidics. Anal Chem 2019; 91:2506-2515. [DOI: 10.1021/acs.analchem.8b05375] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Affiliation(s)
- Richard P. S. de Campos
- Department of Chemistry, University of Toronto, 80 St. George Street, Toronto, Ontario M5S 3H6, Canada
- Donnelly Centre for Cellular and Biomolecular Research, 160 College Street, Toronto, Ontario M5S 3E1, Canada
| | - Darius G. Rackus
- Department of Chemistry, University of Toronto, 80 St. George Street, Toronto, Ontario M5S 3H6, Canada
- Donnelly Centre for Cellular and Biomolecular Research, 160 College Street, Toronto, Ontario M5S 3E1, Canada
| | - Roger Shih
- Department of Chemistry, University of Toronto, 80 St. George Street, Toronto, Ontario M5S 3H6, Canada
- Donnelly Centre for Cellular and Biomolecular Research, 160 College Street, Toronto, Ontario M5S 3E1, Canada
| | - Chen Zhao
- Department of Mechanical and Industrial Engineering, University of Toronto, 5 King’s College Road, Toronto, Ontario M5S 3G8, Canada
| | - Xinyu Liu
- Department of Mechanical and Industrial Engineering, University of Toronto, 5 King’s College Road, Toronto, Ontario M5S 3G8, Canada
| | - Aaron R. Wheeler
- Department of Chemistry, University of Toronto, 80 St. George Street, Toronto, Ontario M5S 3H6, Canada
- Donnelly Centre for Cellular and Biomolecular Research, 160 College Street, Toronto, Ontario M5S 3E1, Canada
- Institute of Biomaterials and Biomedical Engineering, University of Toronto, 164 College Street, Toronto, Ontario M5S 3G9, Canada
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27
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Sinha H, Quach ABV, Vo PQN, Shih SCC. An automated microfluidic gene-editing platform for deciphering cancer genes. LAB ON A CHIP 2018; 18:2300-2312. [PMID: 29989627 DOI: 10.1039/c8lc00470f] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/09/2023]
Abstract
Gene-editing techniques such as RNA-guided endonuclease systems are becoming increasingly popular for phenotypic screening. Such screens are normally conducted in arrayed or pooled formats. There has been considerable interest in recent years to find new technological methods for conducting these gene-editing assays. We report here the first digital microfluidic method that can automate arrayed gene-editing in mammalian cells. Specifically, this method was useful in culturing lung cancer cells for up to six days, as well as implementing automated gene transfection and knockout procedures. In addition, a standardized imaging pipeline to analyse fluorescently labelled cells was also designed and implemented during these procedures. A gene editing assay for interrogating the MAPK/ERK pathway was performed to show the utility of our platform and to determine the effects of knocking out the RAF1 gene in lung cancer cells. In addition to gene knockout, we also treated the cells with an inhibitor, Sorafenib Tosylate, to determine the effects of enzymatic inhibition. The combination of enzymatic inhibition and guide targeting on device resulted in lower drug concentrations for achieving half-inhibitory effects (IC50) compared to cells treated only with the inhibitor, confirming that lung cancer cells are being successfully edited on the device. We propose that this system will be useful for other types of gene-editing assays and applications related to personalized medicine.
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Affiliation(s)
- Hugo Sinha
- Department of Electrical and Computer Engineering, Concordia University, Montréal, Québec, Canada.
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28
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Guzniczak E, Jimenez M, Irwin M, Otto O, Willoughby N, Bridle H. Impact of poloxamer 188 (Pluronic F-68) additive on cell mechanical properties, quantification by real-time deformability cytometry. BIOMICROFLUIDICS 2018; 12:044118. [PMID: 30867863 PMCID: PMC6404947 DOI: 10.1063/1.5040316] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/16/2018] [Accepted: 08/03/2018] [Indexed: 06/09/2023]
Abstract
Advances in cellular therapies have led to the development of new approaches for cell product purification and formulation, e.g., utilizing cell endogenous properties such as size and deformability as a basis for separation from potentially harmful undesirable by-products. However, commonly used additives such as Pluronic F-68 and other poloxamer macromolecules can change the mechanical properties of cells and consequently alter their processing. In this paper, we quantified the short-term effect of Pluronic F-68 on the mechanotype of three different cell types (Jurkat cells, red blood cells, and human embryonic kidney cells) using real-time deformability cytometry. The impact of the additive concentration was assessed in terms of cell size and deformability. We observed that cells respond progressively to the presence of Pluronic F-68 within first 3 h of incubation and become significantly stiffer (p-value < 0.001) in comparison to a serum-free control and a control containing serum. We also observed that the short-term response manifested as cell stiffening is true (p-value < 0.001) for the concentration reaching 1% (w/v) of the poloxamer additive in tested buffers. Additionally, using flow cytometry, we assessed that changes in cell deformability triggered by addition of Pluronic F-68 are not accompanied by size or viability alterations.
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Affiliation(s)
- Ewa Guzniczak
- Institute of Biological Chemistry, Biophysics and Bioengineering, School of Engineering and Physical Science, Heriot-Watt University, Edinburgh Campus, Edinburgh EH14 4AS, United Kingdom
| | - Melanie Jimenez
- School of Engineering, Biomedical Engineering Division, University of Glasgow, Glasgow G12 8LT, United Kingdom
| | - Matthew Irwin
- Institute of Biological Chemistry, Biophysics and Bioengineering, School of Engineering and Physical Science, Heriot-Watt University, Edinburgh Campus, Edinburgh EH14 4AS, United Kingdom
| | - Oliver Otto
- ZIK HIKE, Centre for Innovation Competence - Humoral Immune Reactions in Cardiovascular Diseases, Biomechanics, University of Greifswald, Fleischmannstraße 42-44, 17489 Greifswald, Germany
| | - Nicholas Willoughby
- Institute of Biological Chemistry, Biophysics and Bioengineering, School of Engineering and Physical Science, Heriot-Watt University, Edinburgh Campus, Edinburgh EH14 4AS, United Kingdom
| | - Helen Bridle
- Institute of Biological Chemistry, Biophysics and Bioengineering, School of Engineering and Physical Science, Heriot-Watt University, Edinburgh Campus, Edinburgh EH14 4AS, United Kingdom
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29
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Shah V, Bharatiya B, Shah DO. Effect of molecular weight and diffusivity on the adsorption of PEO-PPO-PEO block copolymers at PTFE-water and oil-water interfaces. Colloid Polym Sci 2018. [DOI: 10.1007/s00396-018-4346-3] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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30
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Wang Y, Ruan Q, Lei ZC, Lin SC, Zhu Z, Zhou L, Yang C. Highly Sensitive and Automated Surface Enhanced Raman Scattering-based Immunoassay for H5N1 Detection with Digital Microfluidics. Anal Chem 2018; 90:5224-5231. [PMID: 29569903 DOI: 10.1021/acs.analchem.8b00002] [Citation(s) in RCA: 77] [Impact Index Per Article: 12.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Digital microfluidics (DMF) is a powerful platform for a broad range of applications, especially immunoassays having multiple steps, due to the advantages of low reagent consumption and high automatization. Surface enhanced Raman scattering (SERS) has been proven as an attractive method for highly sensitive and multiplex detection, because of its remarkable signal amplification and excellent spatial resolution. Here we propose a SERS-based immunoassay with DMF for rapid, automated, and sensitive detection of disease biomarkers. SERS tags labeled with Raman reporter 4-mercaptobenzoic acid (4-MBA) were synthesized with a core@shell nanostructure and showed strong signals, good uniformity, and high stability. A sandwich immunoassay was designed, in which magnetic beads coated with antibodies were used as solid support to capture antigens from samples to form a beads-antibody-antigen immunocomplex. By labeling the immunocomplex with a detection antibody-functionalized SERS tag, antigen can be sensitively detected through the strong SERS signal. The automation capability of DMF can greatly simplify the assay procedure while reducing the risk of exposure to hazardous samples. Quantitative detection of avian influenza virus H5N1 in buffer and human serum was implemented to demonstrate the utility of the DMF-SERS method. The DMF-SERS method shows excellent sensitivity (LOD of 74 pg/mL) and selectivity for H5N1 detection with less assay time (<1 h) and lower reagent consumption (∼30 μL) compared to the standard ELISA method. Therefore, this DMF-SERS method holds great potentials for automated and sensitive detection of a variety of infectious diseases.
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Affiliation(s)
- Yang Wang
- MOE Key Laboratory of Spectrochemical Analysis & Instrumentation, the Key Laboratory of Chemical Biology of Fujian Province, State Key Laboratory of Physical Chemistry of Solid Surfaces, Collaborative Innovation Center of Chemistry for Energy Materials, Department of Chemical Engineering, Department of Chemical Biology, College of Chemistry and Chemical Engineering , Xiamen University , Xiamen 361005 , China
| | - Qingyu Ruan
- MOE Key Laboratory of Spectrochemical Analysis & Instrumentation, the Key Laboratory of Chemical Biology of Fujian Province, State Key Laboratory of Physical Chemistry of Solid Surfaces, Collaborative Innovation Center of Chemistry for Energy Materials, Department of Chemical Engineering, Department of Chemical Biology, College of Chemistry and Chemical Engineering , Xiamen University , Xiamen 361005 , China
| | - Zhi-Chao Lei
- MOE Key Laboratory of Spectrochemical Analysis & Instrumentation, the Key Laboratory of Chemical Biology of Fujian Province, State Key Laboratory of Physical Chemistry of Solid Surfaces, Collaborative Innovation Center of Chemistry for Energy Materials, Department of Chemical Engineering, Department of Chemical Biology, College of Chemistry and Chemical Engineering , Xiamen University , Xiamen 361005 , China
| | - Shui-Chao Lin
- MOE Key Laboratory of Spectrochemical Analysis & Instrumentation, the Key Laboratory of Chemical Biology of Fujian Province, State Key Laboratory of Physical Chemistry of Solid Surfaces, Collaborative Innovation Center of Chemistry for Energy Materials, Department of Chemical Engineering, Department of Chemical Biology, College of Chemistry and Chemical Engineering , Xiamen University , Xiamen 361005 , China
| | - Zhi Zhu
- MOE Key Laboratory of Spectrochemical Analysis & Instrumentation, the Key Laboratory of Chemical Biology of Fujian Province, State Key Laboratory of Physical Chemistry of Solid Surfaces, Collaborative Innovation Center of Chemistry for Energy Materials, Department of Chemical Engineering, Department of Chemical Biology, College of Chemistry and Chemical Engineering , Xiamen University , Xiamen 361005 , China
| | - Leiji Zhou
- MOE Key Laboratory of Spectrochemical Analysis & Instrumentation, the Key Laboratory of Chemical Biology of Fujian Province, State Key Laboratory of Physical Chemistry of Solid Surfaces, Collaborative Innovation Center of Chemistry for Energy Materials, Department of Chemical Engineering, Department of Chemical Biology, College of Chemistry and Chemical Engineering , Xiamen University , Xiamen 361005 , China
| | - Chaoyong Yang
- MOE Key Laboratory of Spectrochemical Analysis & Instrumentation, the Key Laboratory of Chemical Biology of Fujian Province, State Key Laboratory of Physical Chemistry of Solid Surfaces, Collaborative Innovation Center of Chemistry for Energy Materials, Department of Chemical Engineering, Department of Chemical Biology, College of Chemistry and Chemical Engineering , Xiamen University , Xiamen 361005 , China.,Institute of Molecular Medicine, Renji Hospital, Shanghai Jiao Tong University , School of Medicine , Shanghai , 200240 , China
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31
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Husser MC, Vo PQN, Sinha H, Ahmadi F, Shih SCC. An Automated Induction Microfluidics System for Synthetic Biology. ACS Synth Biol 2018. [PMID: 29516725 DOI: 10.1021/acssynbio.8b00025] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
The expression of a recombinant gene in a host organism through induction can be an extensively manual and labor-intensive procedure. Several methods have been developed to simplify the protocol, but none has fully replaced the traditional IPTG-based induction. To simplify this process, we describe the development of an autoinduction platform based on digital microfluidics. This system consists of a 600 nm LED and a light sensor to enable the real-time monitoring of the optical density (OD) samples coordinated with the semicontinuous mixing of a bacterial culture. A hand-held device was designed as a microbioreactor to culture cells and to measure the OD of the bacterial culture. In addition, it serves as a platform for the analysis of regulated protein expression in E. coli without the requirement of standardized well-plates or pipetting-based platforms. Here, we report for the first time, a system that offers great convenience without the user to physically monitor the culture or to manually add inducer at specific times. We characterized our system by looking at several parameters (electrode designs, gap height, and growth rates) required for an autoinducible system. As a first step, we carried out an automated induction optimization assay using a RFP reporter gene to identify conditions suitable for our system. Next, we used our system to identify active thermophilic β-glucosidase enzymes that may be suitable candidates for biomass hydrolysis. Overall, we believe that this platform may be useful for synthetic biology applications that require regulating and analyzing expression of heterologous genes for strain optimization.
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Affiliation(s)
- Mathieu C. Husser
- Department of Biology, Concordia University, Montréal, Québec H4B 1R6, Canada
- Centre for Applied Synthetic Biology, Concordia University, Montréal, Québec H4B 1R6, Canada
| | - Philippe Q. N. Vo
- Department of Electrical and Computer Engineering, Concordia University, Montréal, Québec H3G 1M8, Canada
| | - Hugo Sinha
- Centre for Applied Synthetic Biology, Concordia University, Montréal, Québec H4B 1R6, Canada
- Department of Electrical and Computer Engineering, Concordia University, Montréal, Québec H3G 1M8, Canada
| | - Fatemeh Ahmadi
- Centre for Applied Synthetic Biology, Concordia University, Montréal, Québec H4B 1R6, Canada
- Department of Electrical and Computer Engineering, Concordia University, Montréal, Québec H3G 1M8, Canada
| | - Steve C. C. Shih
- Department of Biology, Concordia University, Montréal, Québec H4B 1R6, Canada
- Centre for Applied Synthetic Biology, Concordia University, Montréal, Québec H4B 1R6, Canada
- Department of Electrical and Computer Engineering, Concordia University, Montréal, Québec H3G 1M8, Canada
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32
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Vo PQN, Husser MC, Ahmadi F, Sinha H, Shih SCC. Image-based feedback and analysis system for digital microfluidics. LAB ON A CHIP 2017; 17:3437-3446. [PMID: 28871290 DOI: 10.1039/c7lc00826k] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
Digital microfluidics (DMF) is a technology that provides a means of manipulating nL-μL volumes of liquids on an array of electrodes. By applying an electric potential to an electrode, these discrete droplets can be controlled in parallel which can be transported, mixed, reacted, and analyzed. Typically, an automation system is interfaced with a DMF device that uses a standard set of basic instructions written by the user to execute droplet operations. Here, we present the first feedback method for DMF that relies on imaging techniques that will allow online detection of droplets without the need to reactivate all destination electrodes. Our system consists of integrating open-source electronics with a CMOS camera and a zoom lens for acquisition of the images that will be used to detect droplets on the device. We also created an algorithm that uses a Hough transform to detect a variety of droplet sizes and to detect singular droplet dispensing and movement failures on the device. As a first test, we applied this feedback system to test droplet movement for a variety of liquids used in cell-based assays and to optimize different feedback actuation schemes to improve droplet movement fidelity. We also applied our system to a colorimetric enzymatic assay to show that our system is capable of biological analysis. Overall, we believe that using our approach of integrating imaging and feedback for DMF can provide a platform for automating biological assays with analysis.
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Affiliation(s)
- Philippe Q N Vo
- Department of Electrical and Computer Engineering, Concordia University, Montréal, Québec, Canada.
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33
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Lønning PE. Comment on "Towards a personalized approach to aromatase inhibitor therapy: a digital microfluidic platform for rapid analysis of estradiol in core-needle-biopsies" by S. Abdulwahab, A. H. C. Ng, M. D. Chamberlain, H. Ahmado, L.-A. Behan, H. Gomaa, R. F. Casper and A. R. Wheeler, Lab Chip, 2017, 17, 1594. LAB ON A CHIP 2017; 17:1594-1602. [PMID: 28816306 DOI: 10.1039/c7lc00170c] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/16/2023]
Abstract
This comment on an article that appeared in Lab on a Chip (Abdulwahab et al., Lab Chip, 2017, 17, 1594) highlights the need for further validation of the proposed method.
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Affiliation(s)
- Per E Lønning
- Department of Clinical Science, Faculty of Medicine, University of Bergen and Department of Oncology, Haukeland University Hospital, Bergen, Norway.
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34
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Latip EA, Coudron L, McDonnell MB, Johnston ID, McCluskey DK, Day R, Tracey MC. Protein droplet actuation on superhydrophobic surfaces: a new approach toward anti-biofouling electrowetting systems. RSC Adv 2017. [DOI: 10.1039/c7ra10920b] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Anti-biofouling behaviour of an electrowetting device using off-the-shelf superhydrophobic materials is demonstrated through protein adsorption measurement and protein-laden droplet actuation.
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Affiliation(s)
| | - L. Coudron
- School of Engineering and Technology
- University of Hertfordshire
- UK
| | - M. B. McDonnell
- School of Engineering and Technology
- University of Hertfordshire
- UK
- Dstl Porton Down
- Salisbury
| | - I. D. Johnston
- School of Engineering and Technology
- University of Hertfordshire
- UK
| | - D. K. McCluskey
- School of Engineering and Technology
- University of Hertfordshire
- UK
| | - R. Day
- School of Engineering and Technology
- University of Hertfordshire
- UK
| | - M. C. Tracey
- School of Engineering and Technology
- University of Hertfordshire
- UK
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35
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Abstract
Digital microfluidics (DMF) is a droplet-based liquid-handling technology that has recently become popular for cell culture and analysis. In DMF, picoliter- to microliter-sized droplets are manipulated on a planar surface using electric fields, thus enabling software-reconfigurable operations on individual droplets, such as move, merge, split, and dispense from reservoirs. Using this technique, multistep cell-based processes can be carried out using simple and compact instrumentation, making DMF an attractive platform for eventual integration into routine biology workflows. In this review, we summarize the state-of-the-art in DMF cell culture, and describe design considerations, types of DMF cell culture, and cell-based applications of DMF.
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Affiliation(s)
- Alphonsus H C Ng
- Institute for Biomaterials and Biomedical Engineering, University of Toronto, Toronto, Ontario M5S 3G9, Canada; .,The Terrence Donnelly Center for Cellular and Biomolecular Research, Toronto, Ontario M5S 3E1, Canada
| | - Bingyu Betty Li
- Institute for Biomaterials and Biomedical Engineering, University of Toronto, Toronto, Ontario M5S 3G9, Canada; .,The Terrence Donnelly Center for Cellular and Biomolecular Research, Toronto, Ontario M5S 3E1, Canada
| | - M Dean Chamberlain
- Institute for Biomaterials and Biomedical Engineering, University of Toronto, Toronto, Ontario M5S 3G9, Canada; .,The Terrence Donnelly Center for Cellular and Biomolecular Research, Toronto, Ontario M5S 3E1, Canada
| | - Aaron R Wheeler
- Institute for Biomaterials and Biomedical Engineering, University of Toronto, Toronto, Ontario M5S 3G9, Canada; .,The Terrence Donnelly Center for Cellular and Biomolecular Research, Toronto, Ontario M5S 3E1, Canada.,Department of Chemistry, University of Toronto, Toronto, Ontario M5S 3H6, Canada
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Gach PC, Shih SC, Sustarich J, Keasling JD, Hillson NJ, Adams PD, Singh AK. A Droplet Microfluidic Platform for Automating Genetic Engineering. ACS Synth Biol 2016; 5:426-33. [PMID: 26830031 DOI: 10.1021/acssynbio.6b00011] [Citation(s) in RCA: 43] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
We present a water-in-oil droplet microfluidic platform for transformation, culture and expression of recombinant proteins in multiple host organisms including bacteria, yeast and fungi. The platform consists of a hybrid digital microfluidic/channel-based droplet chip with integrated temperature control to allow complete automation and integration of plasmid addition, heat-shock transformation, addition of selection medium, culture, and protein expression. The microfluidic format permitted significant reduction in consumption (100-fold) of expensive reagents such as DNA and enzymes compared to the benchtop method. The chip contains a channel to continuously replenish oil to the culture chamber to provide a fresh supply of oxygen to the cells for long-term (∼5 days) cell culture. The flow channel also replenished oil lost to evaporation and increased the number of droplets that could be processed and cultured. The platform was validated by transforming several plasmids into Escherichia coli including plasmids containing genes for fluorescent proteins GFP, BFP and RFP; plasmids with selectable markers for ampicillin or kanamycin resistance; and a Golden Gate DNA assembly reaction. We also demonstrate the applicability of this platform for transformation in widely used eukaryotic organisms such as Saccharomyces cerevisiae and Aspergillus niger. Duration and temperatures of the microfluidic heat-shock procedures were optimized to yield transformation efficiencies comparable to those obtained by benchtop methods with a throughput up to 6 droplets/min. The proposed platform offers potential for automation of molecular biology experiments significantly reducing cost, time and variability while improving throughput.
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Affiliation(s)
- Philip C. Gach
- Technology
Division, Joint BioEnergy Institute (JBEI), Emeryville, California 94608, United States
- Applied
Biosciences and Engineering, Sandia National Laboratories, Livermore, California 94550, United States
| | - Steve C.C. Shih
- Technology
Division, Joint BioEnergy Institute (JBEI), Emeryville, California 94608, United States
- Applied
Biosciences and Engineering, Sandia National Laboratories, Livermore, California 94550, United States
| | - Jess Sustarich
- Technology
Division, Joint BioEnergy Institute (JBEI), Emeryville, California 94608, United States
- Applied
Biosciences and Engineering, Sandia National Laboratories, Livermore, California 94550, United States
| | - Jay D. Keasling
- Fuels
Synthesis Division, Joint BioEnergy Institute (JBEI), Emeryville, California 94608, United States
- Biological
Systems and Engineering Division, Lawrence Berkeley National Lab, Berkeley, California 94720, United States
- Department
of Bioengineering, University of California, Berkeley, California 94720, United States
- Department of Chemical & Biomolecular Engineering, University of California, Berkeley, California 94720, United States
| | - Nathan J. Hillson
- Technology
Division, Joint BioEnergy Institute (JBEI), Emeryville, California 94608, United States
- Fuels
Synthesis Division, Joint BioEnergy Institute (JBEI), Emeryville, California 94608, United States
- Biological
Systems and Engineering Division, Lawrence Berkeley National Lab, Berkeley, California 94720, United States
- DOE Joint Genome Institute, Walnut
Creek, California 94598, United States
| | - Paul D. Adams
- Technology
Division, Joint BioEnergy Institute (JBEI), Emeryville, California 94608, United States
- Department
of Bioengineering, University of California, Berkeley, California 94720, United States
- Molecular
Biophysics and Integrated Bioimaging Division, Lawrence Berkeley National Lab, Berkeley, California 94720, United States
| | - Anup K. Singh
- Technology
Division, Joint BioEnergy Institute (JBEI), Emeryville, California 94608, United States
- Applied
Biosciences and Engineering, Sandia National Laboratories, Livermore, California 94550, United States
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37
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Shamsi MH, Choi K, Ng AHC, Chamberlain MD, Wheeler AR. Electrochemiluminescence on digital microfluidics for microRNA analysis. Biosens Bioelectron 2015; 77:845-52. [PMID: 26516684 DOI: 10.1016/j.bios.2015.10.036] [Citation(s) in RCA: 47] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2015] [Revised: 10/08/2015] [Accepted: 10/12/2015] [Indexed: 01/04/2023]
Abstract
Electrochemiluminescence (ECL) is a sensitive analytical technique with great promise for biological applications, especially when combined with microfluidics. Here, we report the first integration of ECL with digital microfluidics (DMF). ECL detectors were fabricated into the ITO-coated top plates of DMF devices, allowing for the generation of light from electrically excited luminophores in sample droplets. The new system was characterized by making electrochemical and ECL measurements of soluble mixtures of tris(phenanthroline)ruthenium(II) and tripropylamine (TPA) solutions. The system was then validated by application to an oligonucleotide hybridization assay, using magnetic particles bearing 21-mer, deoxyribose analogues of the complement to microRNA-143 (miRNA-143). The system detects single nucleotide mismatches with high specificity, and has a limit of detection of 1.5 femtomoles. The system is capable of detecting miRNA-143 in cancer cell lysates, allowing for the discrimination between the MCF-7 (less aggressive) and MDA-MB-231 (more aggressive) cell lines. We propose that DMF-ECL represents a valuable new tool in the microfluidics toolbox for a wide variety of applications.
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Affiliation(s)
- Mohtashim H Shamsi
- Department of Chemistry, University of Toronto, 80 St George St., Toronto, ON, Canada M5S 3H6; Donnelly Centre for Cellular and Biomolecular Research, 160 College St., Toronto, ON, Canada M5S 3E1
| | - Kihwan Choi
- Department of Chemistry, University of Toronto, 80 St George St., Toronto, ON, Canada M5S 3H6; Donnelly Centre for Cellular and Biomolecular Research, 160 College St., Toronto, ON, Canada M5S 3E1
| | - Alphonsus H C Ng
- Department of Chemistry, University of Toronto, 80 St George St., Toronto, ON, Canada M5S 3H6; Donnelly Centre for Cellular and Biomolecular Research, 160 College St., Toronto, ON, Canada M5S 3E1; Institute of Biomaterials and Biomedical Engineering, University of Toronto, 164 College St., Toronto, ON, Canada M5S 3G9
| | - M Dean Chamberlain
- Department of Chemistry, University of Toronto, 80 St George St., Toronto, ON, Canada M5S 3H6; Donnelly Centre for Cellular and Biomolecular Research, 160 College St., Toronto, ON, Canada M5S 3E1
| | - Aaron R Wheeler
- Department of Chemistry, University of Toronto, 80 St George St., Toronto, ON, Canada M5S 3H6; Donnelly Centre for Cellular and Biomolecular Research, 160 College St., Toronto, ON, Canada M5S 3E1; Institute of Biomaterials and Biomedical Engineering, University of Toronto, 164 College St., Toronto, ON, Canada M5S 3G9.
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38
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Shih SCC, Goyal G, Kim PW, Koutsoubelis N, Keasling JD, Adams PD, Hillson NJ, Singh AK. A Versatile Microfluidic Device for Automating Synthetic Biology. ACS Synth Biol 2015; 4:1151-64. [PMID: 26075958 DOI: 10.1021/acssynbio.5b00062] [Citation(s) in RCA: 63] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
New microbes are being engineered that contain the genetic circuitry, metabolic pathways, and other cellular functions required for a wide range of applications such as producing biofuels, biobased chemicals, and pharmaceuticals. Although currently available tools are useful in improving the synthetic biology process, further improvements in physical automation would help to lower the barrier of entry into this field. We present an innovative microfluidic platform for assembling DNA fragments with 10× lower volumes (compared to that of current microfluidic platforms) and with integrated region-specific temperature control and on-chip transformation. Integration of these steps minimizes the loss of reagents and products compared to that with conventional methods, which require multiple pipetting steps. For assembling DNA fragments, we implemented three commonly used DNA assembly protocols on our microfluidic device: Golden Gate assembly, Gibson assembly, and yeast assembly (i.e., TAR cloning, DNA Assembler). We demonstrate the utility of these methods by assembling two combinatorial libraries of 16 plasmids each. Each DNA plasmid is transformed into Escherichia coli or Saccharomyces cerevisiae using on-chip electroporation and further sequenced to verify the assembly. We anticipate that this platform will enable new research that can integrate this automated microfluidic platform to generate large combinatorial libraries of plasmids and will help to expedite the overall synthetic biology process.
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Affiliation(s)
- Steve C. C. Shih
- Sandia National Laboratories, 7011 East Avenue, Livermore, California 94550, United States
| | - Garima Goyal
- Physical
Bioscience Division, Lawrence Berkeley National Laboratory, 1 Cyclotron
Road, Berkeley, California 94720, United States
| | - Peter W. Kim
- Sandia National Laboratories, 7011 East Avenue, Livermore, California 94550, United States
| | - Nicolas Koutsoubelis
- Physical
Bioscience Division, Lawrence Berkeley National Laboratory, 1 Cyclotron
Road, Berkeley, California 94720, United States
| | - Jay D. Keasling
- Physical
Bioscience Division, Lawrence Berkeley National Laboratory, 1 Cyclotron
Road, Berkeley, California 94720, United States
- Department of Chemical & Biomolecular Engineering, Department of Bioengineering, University of California, Berkeley, California 94720, United States
| | - Paul D. Adams
- Physical
Bioscience Division, Lawrence Berkeley National Laboratory, 1 Cyclotron
Road, Berkeley, California 94720, United States
| | - Nathan J. Hillson
- Physical
Bioscience Division, Lawrence Berkeley National Laboratory, 1 Cyclotron
Road, Berkeley, California 94720, United States
| | - Anup K. Singh
- Sandia National Laboratories, 7011 East Avenue, Livermore, California 94550, United States
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39
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In situ gel-forming AP-57 peptide delivery system for cutaneous wound healing. Int J Pharm 2015; 495:560-571. [PMID: 26363112 DOI: 10.1016/j.ijpharm.2015.09.005] [Citation(s) in RCA: 60] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2015] [Revised: 08/07/2015] [Accepted: 09/07/2015] [Indexed: 02/05/2023]
Abstract
In situ gel-forming system as local drug delivery system in dermal traumas has generated a great interest. Accumulating evidence shows that antimicrobial peptides play pivotal roles in the process of wound healing. Here in this study, to explore the potential application of antimicrobial peptide in wound healing, biodegradable poly(L-lactic acid)-Pluronic L35-poly(L-lactic acid) (PLLA-L35-PLLA) was developed at first. Then based on this polymer, an injectable in situ gel-forming system composed of human antimicrobial peptides 57 (AP-57) loaded nanoparticles and thermosensitive hydrogel was prepared and applied for cutaneous wound healing. AP-57 peptides were enclosed with biocompatible nanoparticles (AP-57-NPs) with high drug loading and encapsulation efficiency. AP-57-NPs were further encapsulated in a thermosensitive hydrogel (AP-57-NPs-H) to facilitate its application in cutaneous wound repair. As a result, AP-57-NPs-H released AP-57 in an extended period and exhibited quite low cytotoxicity and high anti-oxidant activity in vitro. Moreover, AP-57-NPs-H was free-flowing liquid at room temperature, and can form non-flowing gel without any crosslink agent upon applied on the wounds. In vivo wound healing assay using full-thickness dermal defect model of SD rats indicated that AP-57-NPs-H could significantly promote wound healing. At day 14 after operation, AP-57-NPs-H treated group showed nearly complete wound closure of 96.78 ± 3.12%, whereas NS, NPs-H and AP-57-NPs group recovered by about 68.78 ± 4.93%, 81.96 ± 3.26% and 87.80 ± 4.62%, respectively. Histopathological examination suggested that AP-57-NPs-H could promote cutaneous wound healing through enhancing granulation tissue formation, increasing collagen deposition and promoting angiogenesis in the wound tissue. Therefore, AP-57-NPs-H might have potential application in wound healing.
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40
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Building bio-assays with magnetic particles on a digital microfluidic platform. N Biotechnol 2015; 32:485-503. [DOI: 10.1016/j.nbt.2015.03.007] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2014] [Revised: 02/16/2015] [Accepted: 03/13/2015] [Indexed: 12/16/2022]
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41
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Lafrenière NM, Mudrik JM, Ng AHC, Seale B, Spooner N, Wheeler AR. Attractive Design: An Elution Solvent Optimization Platform for Magnetic-Bead-based Fractionation Using Digital Microfluidics and Design of Experiments. Anal Chem 2015; 87:3902-10. [DOI: 10.1021/ac504697r] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Affiliation(s)
- Nelson M. Lafrenière
- Department
of Chemistry, University of Toronto, 80 St George Street, Toronto, Ontario M5S 3H6, Canada
| | - Jared M. Mudrik
- Department
of Chemistry, University of Toronto, 80 St George Street, Toronto, Ontario M5S 3H6, Canada
| | - Alphonsus H. C. Ng
- Institute of Biomaterials and Biomedical Engineering, 164 College Street, Toronto, Ontario M5S 3G9, Canada
| | - Brendon Seale
- Department
of Chemistry, University of Toronto, 80 St George Street, Toronto, Ontario M5S 3H6, Canada
| | - Neil Spooner
- Platform Technologies
and Science Drug Metabolism and Pharmacokinetics, GlaxoSmithKline Research and Development, Ware, Hertfordshire SG12 0DP, United Kingdom
| | - Aaron R. Wheeler
- Department
of Chemistry, University of Toronto, 80 St George Street, Toronto, Ontario M5S 3H6, Canada
- Institute of Biomaterials and Biomedical Engineering, 164 College Street, Toronto, Ontario M5S 3G9, Canada
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42
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Shih SCC, Gach PC, Sustarich J, Simmons BA, Adams PD, Singh S, Singh AK. A droplet-to-digital (D2D) microfluidic device for single cell assays. LAB ON A CHIP 2015; 15:225-36. [PMID: 25354549 DOI: 10.1039/c4lc00794h] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/03/2023]
Abstract
We have developed a new hybrid droplet-to-digital microfluidic platform (D2D) that integrates droplet-in-channel microfluidics with digital microfluidics (DMF) for performing multi-step assays. This D2D platform combines the strengths of the two formats-droplets-in-channel for facile generation of droplets containing single cells, and DMF for on-demand manipulation of droplets including control of different droplet volumes (pL-μL), creation of a dilution series of ionic liquid (IL), and parallel single cell culturing and analysis for IL toxicity screening. This D2D device also allows for automated analysis that includes a feedback-controlled system for merging and splitting of droplets to add reagents, an integrated Peltier element for parallel cell culture at optimum temperature, and an impedance sensing mechanism to control the flow rate for droplet generation and preventing droplet evaporation. Droplet-in-channel is well-suited for encapsulation of single cells as it allows the careful manipulation of flow rates of aqueous phase containing cells and oil to optimize encapsulation. Once single cell containing droplets are generated, they are transferred to a DMF chip via a capillary where they are merged with droplets containing IL and cultured at 30 °C. The DMF chip, in addition to permitting cell culture and reagent (ionic liquid/salt) addition, also allows recovery of individual droplets for off-chip analysis such as further culturing and measurement of ethanol production. The D2D chip was used to evaluate the effect of IL/salt type (four types: NaOAc, NaCl, [C2mim] [OAc], [C2mim] [Cl]) and concentration (four concentrations: 0, 37.5, 75, 150 mM) on the growth kinetics and ethanol production of yeast and as expected, increasing IL concentration led to lower biomass and ethanol production. Specifically, [C2mim] [OAc] had inhibitory effects on yeast growth at concentrations 75 and 150 mM and significantly reduced their ethanol production compared to cells grown in other ILs/salts. The growth curve trends obtained by D2D matched conventional yeast culturing in microtiter wells, validating the D2D platform. We believe that our approach represents a generic platform for multi-step biochemical assays such as drug screening, digital PCR, enzyme assays, immunoassays and cell-based assays.
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Affiliation(s)
- Steve C C Shih
- Sandia National Laboratories, 7011 East Ave, Livermore, CA, USA.
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43
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Gao J, Chen T, Dong C, Jia Y, Mak PI, Vai MI, Martins RP. Adhesion promoter for a multi-dielectric-layer on a digital microfluidic chip. RSC Adv 2015. [DOI: 10.1039/c5ra08202a] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
A silane-based adhesion promoter suitable for a multi-dielectric-layer coating on a digital microfluidic chip is reported.
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Affiliation(s)
- Jie Gao
- State Key Laboratory of Analog and Mixed-Signal VLSI and FST-ECE
- University of Macau
- Avenida da Universidade
- Taipa
- China
| | - Tianlan Chen
- State Key Laboratory of Analog and Mixed-Signal VLSI and FST-ECE
- University of Macau
- Avenida da Universidade
- Taipa
- China
| | - Cheng Dong
- State Key Laboratory of Analog and Mixed-Signal VLSI and FST-ECE
- University of Macau
- Avenida da Universidade
- Taipa
- China
| | - Yanwei Jia
- State Key Laboratory of Analog and Mixed-Signal VLSI and FST-ECE
- University of Macau
- Avenida da Universidade
- Taipa
- China
| | - Pui-In Mak
- State Key Laboratory of Analog and Mixed-Signal VLSI and FST-ECE
- University of Macau
- Avenida da Universidade
- Taipa
- China
| | - Mang-I. Vai
- State Key Laboratory of Analog and Mixed-Signal VLSI and FST-ECE
- University of Macau
- Avenida da Universidade
- Taipa
- China
| | - Rui P. Martins
- State Key Laboratory of Analog and Mixed-Signal VLSI and FST-ECE
- University of Macau
- Avenida da Universidade
- Taipa
- China
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44
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Ng AHC, Lee M, Choi K, Fischer AT, Robinson JM, Wheeler AR. Digital microfluidic platform for the detection of rubella infection and immunity: a proof of concept. Clin Chem 2014; 61:420-9. [PMID: 25512641 DOI: 10.1373/clinchem.2014.232181] [Citation(s) in RCA: 51] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
BACKGROUND Whereas disease surveillance for infectious diseases such as rubella is important, it is critical to identify pregnant women at risk of passing rubella to their offspring, which can be fatal and can result in congenital rubella syndrome (CRS). The traditional centralized model for diagnosing rubella is cost-prohibitive in resource-limited settings, representing a major obstacle to the prevention of CRS. As a step toward decentralized diagnostic systems, we developed a proof-of-concept digital microfluidic (DMF) diagnostic platform that possesses the flexibility and performance of automated immunoassay platforms used in central facilities, but with a form factor the size of a shoebox. METHODS DMF immunoassays were developed with integrated sample preparation for the detection of rubella virus (RV) IgG and IgM. The performance (sensitivity and specificity) of the assays was evaluated with serum and plasma samples from a commercial antirubella mixed-titer performance panel. RESULTS The new platform performed the essential processing steps, including sample aliquoting for 4 parallel assays, sample dilution, and IgG blocking. Testing of performance panel samples yielded diagnostic sensitivity and specificity of 100% and 100% for both RV IgG and RV IgM. With 1.8 μL sample per assay, 4 parallel assays were performed in approximately 30 min with <10% mean CV. CONCLUSIONS This proof of concept establishes DMF-powered immunoassays as being potentially useful for the diagnosis of infectious disease.
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Affiliation(s)
- Alphonsus H C Ng
- Institute of Biomaterials and Biomedical Engineering, Donnelly Centre for Cellular and Biomolecular Research, Toronto, ON, Canada
| | - Misan Lee
- Innis College, and Donnelly Centre for Cellular and Biomolecular Research, Toronto, ON, Canada
| | - Kihwan Choi
- Donnelly Centre for Cellular and Biomolecular Research, Toronto, ON, Canada; Department of Chemistry, University of Toronto, Toronto, ON, Canada
| | | | | | - Aaron R Wheeler
- Institute of Biomaterials and Biomedical Engineering, Donnelly Centre for Cellular and Biomolecular Research, Toronto, ON, Canada; Department of Chemistry, University of Toronto, Toronto, ON, Canada;
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45
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Aijian AP, Garrell RL. Digital microfluidics for automated hanging drop cell spheroid culture. ACTA ACUST UNITED AC 2014; 20:283-95. [PMID: 25510471 DOI: 10.1177/2211068214562002] [Citation(s) in RCA: 55] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2014] [Indexed: 11/15/2022]
Abstract
Cell spheroids are multicellular aggregates, grown in vitro, that mimic the three-dimensional morphology of physiological tissues. Although there are numerous benefits to using spheroids in cell-based assays, the adoption of spheroids in routine biomedical research has been limited, in part, by the tedious workflow associated with spheroid formation and analysis. Here we describe a digital microfluidic platform that has been developed to automate liquid-handling protocols for the formation, maintenance, and analysis of multicellular spheroids in hanging drop culture. We show that droplets of liquid can be added to and extracted from through-holes, or "wells," and fabricated in the bottom plate of a digital microfluidic device, enabling the formation and assaying of hanging drops. Using this digital microfluidic platform, spheroids of mouse mesenchymal stem cells were formed and maintained in situ for 72 h, exhibiting good viability (>90%) and size uniformity (% coefficient of variation <10% intraexperiment, <20% interexperiment). A proof-of-principle drug screen was performed on human colorectal adenocarcinoma spheroids to demonstrate the ability to recapitulate physiologically relevant phenomena such as insulin-induced drug resistance. With automatable and flexible liquid handling, and a wide range of in situ sample preparation and analysis capabilities, the digital microfluidic platform provides a viable tool for automating cell spheroid culture and analysis.
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Affiliation(s)
- Andrew P Aijian
- Department of Bioengineering, University of California, Los Angeles, CA, USA
| | - Robin L Garrell
- Department of Bioengineering, University of California, Los Angeles, CA, USA Department of Chemistry and Biochemistry, University of California, Los Angeles, CA, USA California NanoSystems Institute, University of California, Los Angeles, CA, USA
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46
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Digital microfluidic processing of mammalian embryos for vitrification. PLoS One 2014; 9:e108128. [PMID: 25250666 PMCID: PMC4176959 DOI: 10.1371/journal.pone.0108128] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2014] [Accepted: 08/25/2014] [Indexed: 11/19/2022] Open
Abstract
Cryopreservation is a key technology in biology and clinical practice. This paper presents a digital microfluidic device that automates sample preparation for mammalian embryo vitrification. Individual micro droplets manipulated on the microfluidic device were used as micro-vessels to transport a single mouse embryo through a complete vitrification procedure. Advantages of this approach, compared to manual operation and channel-based microfluidic vitrification, include automated operation, cryoprotectant concentration gradient generation, and feasibility of loading and retrieval of embryos.
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47
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Au SH, Chamberlain MD, Mahesh S, Sefton MV, Wheeler AR. Hepatic organoids for microfluidic drug screening. LAB ON A CHIP 2014; 14:3290-9. [PMID: 24984750 DOI: 10.1039/c4lc00531g] [Citation(s) in RCA: 96] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/03/2023]
Abstract
We introduce the microfluidic organoids for drug screening (MODS) platform, a digital microfluidic system that is capable of generating arrays of individually addressable, free-floating, three-dimensional hydrogel-based microtissues (or 'organoids'). Here, we focused on liver organoids, driven by the need for early-stage screening methods for hepatotoxicity that enable a "fail early, fail cheaply" strategy in drug discovery. We demonstrate that arrays of hepatic organoids can be formed from co-cultures of HepG2 and NIH-3T3 cells embedded in hydrogel matrices. The organoids exhibit fibroblast-dependent contractile behaviour, and their albumin secretion profiles and cytochrome P450 3A4 activities are better mimics of in vivo liver tissue than comparable two-dimensional cell culture systems. As proof of principle for screening, MODS was used to generate and analyze the effects of a dilution series of acetaminophen on apoptosis and necrosis. With further development, we propose that the MODS platform may be a cost-effective tool in a "fail early, fail cheaply" paradigm of drug development.
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Affiliation(s)
- Sam H Au
- Institute of Biomaterials and Biomedical Engineering, University of Toronto, 164 College St., Toronto, ON M5S 3G9, Canada.
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48
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Kühnemund M, Witters D, Nilsson M, Lammertyn J. Circle-to-circle amplification on a digital microfluidic chip for amplified single molecule detection. LAB ON A CHIP 2014; 14:2983-2992. [PMID: 24934991 DOI: 10.1039/c4lc00348a] [Citation(s) in RCA: 58] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
We demonstrate a novel digital microfluidic nucleic acid amplification concept which is based on padlock probe mediated DNA detection and isothermal circle-to-circle amplification (C2CA). This assay platform combines two digital approaches. First, digital microfluidic manipulation of droplets which serve as micro-reaction chambers and shuttling magnetic particles between these droplets facilitates the integration of complex solid phase multistep assays. We demonstrate an optimized novel particle extraction and transfer protocol for superparamagnetic particles on a digital microfluidic chip that allows for nearly 100% extraction efficiencies securing high assay performance. Second, the compartmentalization required for digital single molecule detection is solved by simple molecular biological means, circumventing the need for complex microfabrication procedures necessary for most, if not all, other digital nucleic acid detection methods. For that purpose, padlock probes are circularized in a strictly target dependent ligation reaction and amplified through two rounds of rolling circle amplification, including an intermediate digestion step. The reaction results in hundreds of 500 nm sized individually countable DNA nanospheres per detected target molecule. We demonstrate that integrated miniaturized digital microfluidic C2CA results in equally high numbers of C2CA products μL(-1) as off-chip tube control experiments indicating high assay performance without signal loss. As low as 1 aM synthetic Pseudomonas aeruginosa DNA was detected with a linear dynamic range over 4 orders of magnitude up to 10 fM proving excellent suitability for infectious disease diagnostics.
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Affiliation(s)
- Malte Kühnemund
- Science for Life Laboratory, Department of Immunology, Genetics and Pathology, Uppsala University, Box 815, 751 08 Uppsala, Sweden
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49
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Hou J, Li J, Sun J, Ai S, Wang M. Nitrogen-doped photoluminescent carbon nanospheres: green, simple synthesis via hair and application as a sensor for Hg2+ions. RSC Adv 2014. [DOI: 10.1039/c4ra04209c] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
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50
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Fobel R, Kirby AE, Ng AHC, Farnood RR, Wheeler AR. Paper microfluidics goes digital. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2014; 26:2838-43. [PMID: 24458780 DOI: 10.1002/adma.201305168] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/17/2013] [Revised: 11/29/2013] [Indexed: 05/20/2023]
Abstract
The first example of so-called "digital microfluidics" (DMF) implemented on paper by inkjet printing is reported. A sandwich enzyme-linked immunosorbent assay (ELISA) is demonstrated as an example of a complex, multistep protocol that would be difficult to achieve with capillary-driven paper microfluidics. Furthermore, it is shown that paper-based DMF devices have comparable performance to traditional photolithographically patterned DMF devices at a fraction of the cost.
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Affiliation(s)
- Ryan Fobel
- Institute for Biomaterials and Biomedical Engineering, University of Toronto, 164 College St., Toronto, ON, M5S 3E1, Canada
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