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Sattari A, Hanafizadeh P, Hoorfar M. Multiphase flow in microfluidics: From droplets and bubbles to the encapsulated structures. Adv Colloid Interface Sci 2020; 282:102208. [PMID: 32721624 DOI: 10.1016/j.cis.2020.102208] [Citation(s) in RCA: 30] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2020] [Revised: 05/19/2020] [Accepted: 07/04/2020] [Indexed: 12/14/2022]
Abstract
Microfluidic technologies have a unique ability to control more precisely and effectively on two-phase flow systems in comparison with macro systems. Controlling the size of the droplets and bubbles has led to an ever-increasing expansion of this technology in two-phase systems. Liquid-liquid and gas-liquid two-phase flows because of their numerous applications in different branches such as reactions, synthesis, emulsions, cosmetic, food, drug delivery, etc. have been the most critical two-phase flows in microfluidic systems. This review highlights recent progress in two-phase flows in microfluidic devices. The fundamentals of two-phase flows, including some essential dimensionless numbers, governing equations, and some most well-known numerical methods are firstly introduced, followed by a review of standard methods for producing segmented flows such as emulsions in microfluidic systems. Then various encapsulated structures, a common two-phase flow structure in microfluidic devices, and different methods of their production are reviewed. Finally, applications of two-phase microfluidic flows in drug-delivery, biotechnology, mixing, and microreactors are briefly discussed.
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52
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Neun S, Zurek PJ, Kaminski TS, Hollfelder F. Ultrahigh throughput screening for enzyme function in droplets. Methods Enzymol 2020; 643:317-343. [PMID: 32896286 DOI: 10.1016/bs.mie.2020.06.002] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Water-in-oil droplets, made and handled in microfluidic devices, provide a new experimental format, in which ultrahigh throughput experiments can be conducted faster and with minimal reagent consumption. An increasing number of studies have emerged that applied this approach to directed evolution and metagenomic screening of enzyme catalysts. Here, we review the considerations necessary to implement robust workflows, based on choices of device design, detection modes, emulsion formulations and substrates, and scope out which enzyme classes have become amenable to droplet screening.
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Affiliation(s)
- Stefanie Neun
- Department of Biochemistry, University of Cambridge, Cambridge, United Kingdom
| | - Paul J Zurek
- Department of Biochemistry, University of Cambridge, Cambridge, United Kingdom
| | - Tomasz S Kaminski
- Department of Biochemistry, University of Cambridge, Cambridge, United Kingdom
| | - Florian Hollfelder
- Department of Biochemistry, University of Cambridge, Cambridge, United Kingdom.
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53
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Bowman EK, Alper HS. Microdroplet-Assisted Screening of Biomolecule Production for Metabolic Engineering Applications. Trends Biotechnol 2020; 38:701-714. [DOI: 10.1016/j.tibtech.2019.11.002] [Citation(s) in RCA: 27] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2019] [Revised: 10/30/2019] [Accepted: 11/07/2019] [Indexed: 12/19/2022]
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Payne EM, Holland-Moritz DA, Sun S, Kennedy RT. High-throughput screening by droplet microfluidics: perspective into key challenges and future prospects. LAB ON A CHIP 2020; 20:2247-2262. [PMID: 32500896 DOI: 10.1039/d0lc00347f] [Citation(s) in RCA: 73] [Impact Index Per Article: 18.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/09/2023]
Abstract
In two decades of development, impressive strides have been made for automating basic laboratory operations in droplet-based microfluidics, allowing the emergence of a new form of high-throughput screening and experimentation in nanoliter to femtoliter volumes. Despite advancements in droplet storage, manipulation, and analysis, the field has not yet been widely adapted for many high-throughput screening (HTS) applications. Broad adoption and commercial development of these techniques require robust implementation of strategies for the stable storage, chemical containment, generation of libraries, sample tracking, and chemical analysis of these small samples. We discuss these challenges for implementing droplet HTS and highlight key strategies that have begun to address these concerns. Recent advances in the field leave us optimistic about the future prospects of this rapidly developing technology.
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Affiliation(s)
- Emory M Payne
- Department of Chemistry, University of Michigan, Ann Arbor, MI, USA.
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Programmable µChopper Device with On-Chip Droplet Mergers for Continuous Assay Calibration. MICROMACHINES 2020; 11:mi11060620. [PMID: 32630555 PMCID: PMC7344876 DOI: 10.3390/mi11060620] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/05/2020] [Revised: 06/18/2020] [Accepted: 06/22/2020] [Indexed: 12/21/2022]
Abstract
While droplet-based microfluidics is a powerful technique with transformative applications, most devices are passively operated and thus have limited real-time control over droplet contents. In this report, an automated droplet-based microfluidic device with pneumatic pumps and salt water electrodes was developed to generate and coalesce up to six aqueous-in-oil droplets (2.77 nL each). Custom control software combined six droplets drawn from any of four inlet reservoirs. Using our μChopper method for lock-in fluorescence detection, we first accomplished continuous linear calibration and quantified an unknown sample. Analyte-independent signal drifts and even an abrupt decrease in excitation light intensity were corrected in real-time. The system was then validated with homogeneous insulin immunoassays that showed a nonlinear response. On-chip droplet merging with antibody-oligonucleotide (Ab-oligo) probes, insulin standards, and buffer permitted the real-time calibration and correction of large signal drifts. Full calibrations (LODconc = 2 ng mL−1 = 300 pM; LODamt = 5 amol) required <1 min with merely 13.85 nL of Ab-oligo reagents, giving cost-savings 160-fold over the standard well-plate format while also automating the workflow. This proof-of-concept device—effectively a microfluidic digital-to-analog converter—is readily scalable to more droplets, and it is well-suited for the real-time automation of bioassays that call for expensive reagents.
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56
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Brower KK, Carswell-Crumpton C, Klemm S, Cruz B, Kim G, Calhoun SGK, Nichols L, Fordyce PM. Double emulsion flow cytometry with high-throughput single droplet isolation and nucleic acid recovery. LAB ON A CHIP 2020; 20:2062-2074. [PMID: 32417874 PMCID: PMC7670282 DOI: 10.1039/d0lc00261e] [Citation(s) in RCA: 46] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/04/2023]
Abstract
Droplet microfluidics has made large impacts in diverse areas such as enzyme evolution, chemical product screening, polymer engineering, and single-cell analysis. However, while droplet reactions have become increasingly sophisticated, phenotyping droplets by a fluorescent signal and sorting them to isolate individual variants-of-interest at high-throughput remains challenging. Here, we present sdDE-FACS (s[combining low line]ingle d[combining low line]roplet D[combining low line]ouble E[combining low line]mulsion-FACS), a new method that uses a standard flow cytometer to phenotype, select, and isolate individual double emulsion droplets of interest. Using a 130 μm nozzle at high sort frequency (12-14 kHz), we demonstrate detection of droplet fluorescence signals with a dynamic range spanning 5 orders of magnitude and robust post-sort recovery of intact double emulsion (DE) droplets using 2 commercially-available FACS instruments. We report the first demonstration of single double emulsion droplet isolation with post-sort recovery efficiencies >70%, equivalent to the capabilities of single-cell FACS. Finally, we establish complete downstream recovery of nucleic acids from single, sorted double emulsion droplets via qPCR with little to no cross-contamination. sdDE-FACS marries the full power of droplet microfluidics with flow cytometry to enable a variety of new droplet assays, including rare variant isolation and multiparameter single-cell analysis.
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Affiliation(s)
- Kara K Brower
- Department of Bioengineering, Stanford University, Stanford, California, USA.
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57
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Watterson WJ, Tanyeri M, Watson AR, Cham CM, Shan Y, Chang EB, Eren AM, Tay S. Droplet-based high-throughput cultivation for accurate screening of antibiotic resistant gut microbes. eLife 2020; 9:e56998. [PMID: 32553109 PMCID: PMC7351490 DOI: 10.7554/elife.56998] [Citation(s) in RCA: 61] [Impact Index Per Article: 15.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2020] [Accepted: 06/14/2020] [Indexed: 12/16/2022] Open
Abstract
Traditional cultivation approaches in microbiology are labor-intensive, low-throughput, and yield biased sampling of environmental microbes due to ecological and evolutionary factors. New strategies are needed for ample representation of rare taxa and slow-growers that are often outcompeted by fast-growers in cultivation experiments. Here we describe a microfluidic platform that anaerobically isolates and cultivates microbial cells in millions of picoliter droplets and automatically sorts them based on colony density to enhance slow-growing organisms. We applied our strategy to a fecal microbiota transplant (FMT) donor stool using multiple growth media, and found significant increase in taxonomic richness and larger representation of rare and clinically relevant taxa among droplet-grown cells compared to conventional plates. Furthermore, screening the FMT donor stool for antibiotic resistance revealed 21 populations that evaded detection in plate-based assessment of antibiotic resistance. Our method improves cultivation-based surveys of diverse microbiomes to gain deeper insights into microbial functioning and lifestyles.
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Affiliation(s)
- William J Watterson
- Pritzker School of Molecular Engineering, The University of ChicagoChicagoUnited States
- Institute for Genomics and Systems Biology, The University of ChicagoChicagoUnited States
| | - Melikhan Tanyeri
- Pritzker School of Molecular Engineering, The University of ChicagoChicagoUnited States
- Institute for Genomics and Systems Biology, The University of ChicagoChicagoUnited States
- Department of Engineering, Duquesne UniversityPittsburghUnited States
| | - Andrea R Watson
- Department of Medicine, The University of ChicagoChicagoUnited States
| | - Candace M Cham
- Department of Medicine, The University of ChicagoChicagoUnited States
| | - Yue Shan
- Department of Medicine, The University of ChicagoChicagoUnited States
| | - Eugene B Chang
- Department of Medicine, The University of ChicagoChicagoUnited States
| | - A Murat Eren
- Department of Medicine, The University of ChicagoChicagoUnited States
- Graduate Program in the Biophysical Sciences, The University of ChicagoChicagoUnited States
- Josephine Bay Paul Center for Comparative Molecular Biology and Evolution, Marine Biological LaboratoryWoods HoleUnited States
| | - Savaş Tay
- Pritzker School of Molecular Engineering, The University of ChicagoChicagoUnited States
- Institute for Genomics and Systems Biology, The University of ChicagoChicagoUnited States
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58
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Sesen M, Whyte G. Image-Based Single Cell Sorting Automation in Droplet Microfluidics. Sci Rep 2020; 10:8736. [PMID: 32457421 PMCID: PMC7250914 DOI: 10.1038/s41598-020-65483-2] [Citation(s) in RCA: 50] [Impact Index Per Article: 12.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2019] [Accepted: 05/06/2020] [Indexed: 12/13/2022] Open
Abstract
The recent boom in single-cell omics has brought researchers one step closer to understanding the biological mechanisms associated with cell heterogeneity. Rare cells that have historically been obscured by bulk measurement techniques are being studied by single cell analysis and providing valuable insight into cell function. To support this progress, novel upstream capabilities are required for single cell preparation for analysis. Presented here is a droplet microfluidic, image-based single-cell sorting technique that is flexible and programmable. The automated system performs real-time dual-camera imaging (brightfield & fluorescent), processing, decision making and sorting verification. To demonstrate capabilities, the system was used to overcome the Poisson loading problem by sorting for droplets containing a single red blood cell with 85% purity. Furthermore, fluorescent imaging and machine learning was used to load single K562 cells amongst clusters based on their instantaneous size and circularity. The presented system aspires to replace manual cell handling techniques by translating expert knowledge into cell sorting automation via machine learning algorithms. This powerful technique finds application in the enrichment of single cells based on their micrographs for further downstream processing and analysis.
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Affiliation(s)
- Muhsincan Sesen
- Heriot-Watt University, Institute of Biological Chemistry, Biophysics and Bioengineering, Edinburgh, EH14 4AS, United Kingdom
- Imperial College London, Department of Bioengineering, London, SW7 2AZ, United Kingdom
| | - Graeme Whyte
- Heriot-Watt University, Institute of Biological Chemistry, Biophysics and Bioengineering, Edinburgh, EH14 4AS, United Kingdom.
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59
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Xu P, Modavi C, Demaree B, Twigg F, Liang B, Sun C, Zhang W, Abate AR. Microfluidic automated plasmid library enrichment for biosynthetic gene cluster discovery. Nucleic Acids Res 2020; 48:e48. [PMID: 32095820 PMCID: PMC7192590 DOI: 10.1093/nar/gkaa131] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2019] [Revised: 01/22/2020] [Accepted: 02/19/2020] [Indexed: 12/13/2022] Open
Abstract
Microbial biosynthetic gene clusters are a valuable source of bioactive molecules. However, because they typically represent a small fraction of genomic material in most metagenomic samples, it remains challenging to deeply sequence them. We present an approach to isolate and sequence gene clusters in metagenomic samples using microfluidic automated plasmid library enrichment. Our approach provides deep coverage of the target gene cluster, facilitating reassembly. We demonstrate the approach by isolating and sequencing type I polyketide synthase gene clusters from an Antarctic soil metagenome. Our method promotes the discovery of functional-related genes and biosynthetic pathways.
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Affiliation(s)
- Peng Xu
- Department of Bioengineering and Therapeutic Sciences, University of California, San Francisco, San Francisco, CA, USA
| | - Cyrus Modavi
- Department of Bioengineering and Therapeutic Sciences, University of California, San Francisco, San Francisco, CA, USA
| | - Benjamin Demaree
- Department of Bioengineering and Therapeutic Sciences, University of California, San Francisco, San Francisco, CA, USA
- UC Berkeley-UCSF Graduate Program in Bioengineering, University of California, San Francisco, CA, USA
| | - Frederick Twigg
- Department of Chemical and Biomolecular Engineering, University of California Berkeley, Berkeley, CA, USA
| | - Benjamin Liang
- Department of Bioengineering and Therapeutic Sciences, University of California, San Francisco, San Francisco, CA, USA
| | - Chen Sun
- Department of Bioengineering and Therapeutic Sciences, University of California, San Francisco, San Francisco, CA, USA
| | - Wenjun Zhang
- Department of Chemical and Biomolecular Engineering, University of California Berkeley, Berkeley, CA, USA
- Chan Zuckerberg Biohub, San Francisco, CA, USA
| | - Adam R Abate
- Department of Bioengineering and Therapeutic Sciences, University of California, San Francisco, San Francisco, CA, USA
- Chan Zuckerberg Biohub, San Francisco, CA, USA
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60
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“Development and application of analytical detection techniques for droplet-based microfluidics”-A review. Anal Chim Acta 2020; 1113:66-84. [DOI: 10.1016/j.aca.2020.03.011] [Citation(s) in RCA: 34] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2019] [Revised: 03/02/2020] [Accepted: 03/05/2020] [Indexed: 01/03/2023]
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61
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Isozaki A, Nakagawa Y, Loo MH, Shibata Y, Tanaka N, Setyaningrum DL, Park JW, Shirasaki Y, Mikami H, Huang D, Tsoi H, Riche CT, Ota T, Miwa H, Kanda Y, Ito T, Yamada K, Iwata O, Suzuki K, Ohnuki S, Ohya Y, Kato Y, Hasunuma T, Matsusaka S, Yamagishi M, Yazawa M, Uemura S, Nagasawa K, Watarai H, Di Carlo D, Goda K. Sequentially addressable dielectrophoretic array for high-throughput sorting of large-volume biological compartments. SCIENCE ADVANCES 2020; 6:eaba6712. [PMID: 32524002 PMCID: PMC7259936 DOI: 10.1126/sciadv.aba6712] [Citation(s) in RCA: 44] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/23/2019] [Accepted: 03/25/2020] [Indexed: 05/27/2023]
Abstract
Droplet microfluidics has become a powerful tool in precision medicine, green biotechnology, and cell therapy for single-cell analysis and selection by virtue of its ability to effectively confine cells. However, there remains a fundamental trade-off between droplet volume and sorting throughput, limiting the advantages of droplet microfluidics to small droplets (<10 pl) that are incompatible with long-term maintenance and growth of most cells. We present a sequentially addressable dielectrophoretic array (SADA) sorter to overcome this problem. The SADA sorter uses an on-chip array of electrodes activated and deactivated in a sequence synchronized to the speed and position of a passing target droplet to deliver an accumulated dielectrophoretic force and gently pull it in the direction of sorting in a high-speed flow. We use it to demonstrate large-droplet sorting with ~20-fold higher throughputs than conventional techniques and apply it to long-term single-cell analysis of Saccharomyces cerevisiae based on their growth rate.
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Affiliation(s)
- A. Isozaki
- Department of Chemistry, Graduate School of Science, University of Tokyo, East Chemistry Building, Room 213, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan
- Kanagawa Institute of Industrial Science and Technology, 3-2-1 Sakado, Takatsu-ku, Kawasaki-shi, Kanagawa 213-0012, Japan
| | - Y. Nakagawa
- Department of Chemistry, Graduate School of Science, University of Tokyo, East Chemistry Building, Room 213, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan
| | - M. H. Loo
- Department of Chemistry, Graduate School of Science, University of Tokyo, East Chemistry Building, Room 213, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan
| | - Y. Shibata
- Department of Chemistry, Graduate School of Science, University of Tokyo, East Chemistry Building, Room 213, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan
| | - N. Tanaka
- Department of Chemistry, Graduate School of Science, University of Tokyo, East Chemistry Building, Room 213, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan
| | - D. L. Setyaningrum
- Department of Chemistry, Graduate School of Science, University of Tokyo, East Chemistry Building, Room 213, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan
| | - J.-W. Park
- Department of Chemistry, Graduate School of Science, University of Tokyo, East Chemistry Building, Room 213, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan
| | - Y. Shirasaki
- Department of Biological Sciences, Graduate School of Science, University of Tokyo, Faculty of Science Building 1 (East), Room 575, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan
| | - H. Mikami
- Department of Chemistry, Graduate School of Science, University of Tokyo, East Chemistry Building, Room 213, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan
| | - D. Huang
- Department of Chemistry, Graduate School of Science, University of Tokyo, East Chemistry Building, Room 213, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan
| | - H. Tsoi
- Department of Chemistry, Graduate School of Science, University of Tokyo, East Chemistry Building, Room 213, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan
| | - C. T. Riche
- Department of Bioengineering, Samueli School of Engineering, University of California, Los Angeles, 420 Westwood Plaza, 5121E Engineering V, Los Angeles, CA 90095, USA
| | - T. Ota
- Department of Chemistry, Graduate School of Science, University of Tokyo, East Chemistry Building, Room 213, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan
| | - H. Miwa
- Department of Chemistry, Graduate School of Science, University of Tokyo, East Chemistry Building, Room 213, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan
| | - Y. Kanda
- Department of Chemistry, Graduate School of Science, University of Tokyo, East Chemistry Building, Room 213, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan
| | - T. Ito
- Department of Chemistry, Graduate School of Science, University of Tokyo, East Chemistry Building, Room 213, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan
- Japan Science and Technology Agency, 4-1-8, Honcho, Kawaguchi-shi, Saitama 332-0012, Japan
| | - K. Yamada
- R&D Department, euglena Co., Ltd., 75-1, Ono-machi, Tsurumi-ku, Yokohama-shi 230-0046, Japan
| | - O. Iwata
- R&D Department, euglena Co., Ltd., 75-1, Ono-machi, Tsurumi-ku, Yokohama-shi 230-0046, Japan
| | - K. Suzuki
- R&D Department, euglena Co., Ltd., 75-1, Ono-machi, Tsurumi-ku, Yokohama-shi 230-0046, Japan
| | - S. Ohnuki
- Department of Integrated Biosciences, Graduate School of Frontier Sciences, University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa, Chiba 277-8562, Japan
| | - Y. Ohya
- Department of Integrated Biosciences, Graduate School of Frontier Sciences, University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa, Chiba 277-8562, Japan
- AIST-UTokyo Advanced Operando-Measurement Technology Open Innovation Laboratory (OPERANDO-OIL), National Institute of Advanced Industrial Science and Technology (AIST), 5-1-5 Kashiwanoha, Kashiwa, Chiba 277-8589, Japan
| | - Y. Kato
- Graduate School of Science, Technology Innovation, Kobe University, 1-1 Rokkodai, Nada, Kobe 657-8501, Japan
| | - T. Hasunuma
- Graduate School of Science, Technology Innovation, Kobe University, 1-1 Rokkodai, Nada, Kobe 657-8501, Japan
- Engineering Biology Research Center, Kobe University, 1-1 Rokkodai, Nada, Kobe 657-8501, Japan
| | - S. Matsusaka
- Clinical Research and Regional Innovation, University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki 305-8575, Japan
| | - M. Yamagishi
- Department of Biological Sciences, Graduate School of Science, University of Tokyo, Faculty of Science Building 1 (East), Room 575, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan
| | - M. Yazawa
- Department of Rehabilitation and Regenerative Medicine, Pharmacology, Columbia University, 650 West 168th Street, BB1108, New York, NY 10032, USA
| | - S. Uemura
- Department of Biological Sciences, Graduate School of Science, University of Tokyo, Faculty of Science Building 1 (East), Room 575, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan
| | - K. Nagasawa
- Division of Stem Cell Cellomics, Institute of Medical Science, University of Tokyo, 4-6-1 Shirokanedai, Minato-ku, Tokyo 108-8639, Japan
| | - H. Watarai
- Division of Stem Cell Cellomics, Institute of Medical Science, University of Tokyo, 4-6-1 Shirokanedai, Minato-ku, Tokyo 108-8639, Japan
- Department of Immunology and Stem Cell Biology, Faculty of Medicine, Institute of Medical, Pharmaceutical and Health Sciences, Kanazawa University, 13-1 Takara-machi, Kanazawa, Ishikawa 920-8640, Japan
| | - D. Di Carlo
- Department of Bioengineering, Samueli School of Engineering, University of California, Los Angeles, 420 Westwood Plaza, 5121E Engineering V, Los Angeles, CA 90095, USA
| | - K. Goda
- Department of Chemistry, Graduate School of Science, University of Tokyo, East Chemistry Building, Room 213, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan
- Department of Bioengineering, Samueli School of Engineering, University of California, Los Angeles, 420 Westwood Plaza, 5121E Engineering V, Los Angeles, CA 90095, USA
- Japan Science and Technology Agency, 4-1-8, Honcho, Kawaguchi-shi, Saitama 332-0012, Japan
- Institute of Technological Sciences, Wuhan University, Hubei 430072, China
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62
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Karamitros CS, Morvan M, Vigne A, Lim J, Gruner P, Beneyton T, Vrignon J, Baret JC. Bacterial Expression Systems for Enzymatic Activity in Droplet-Based Microfluidics. Anal Chem 2020; 92:4908-4916. [PMID: 31909981 DOI: 10.1021/acs.analchem.9b04969] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
Functional screenings in droplet-based microfluidics require the analysis of various types of activities of individual cells. When screening for enzymatic activities, the link between the enzyme of interest and the information-baring molecule, the DNA, must be maintained to relate phenotypes to genotypes. This linkage is crucial in directed evolution experiments or for the screening of natural diversity. Micro-organisms are classically used to express enzymes from nucleic acid sequences. However, little information is available regarding the most suitable expression system for the sensitive detection of enzymatic activity at the single-cell level in droplet-based microfluidics. Here, we compare three different expression systems for l-asparaginase (l-asparagine amidohydrolase, EC 3.5.1.1), an enzyme of therapeutic interest that catalyzes the conversion of l-asparagine to l-aspartic acid and ammonia. We developed three expression vectors to produce and localize l-asparaginase (l-ASNase) in E. coli either in the cytoplasm, on the surface of the inner membrane (display), or in the periplasm. We show that the periplasmic expression is the most optimal strategy combining both a good yield and a good accessibility for the substrate without the need for lysing the cells. We suggest that periplasmic expression may provide a very efficient platform for screening applications at the single-cell level in microfluidics.
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Affiliation(s)
- Christos S Karamitros
- Max Planck Institute for Biophysical Chemistry, Am Fassberg 11, D37077 Goettingen, Germany.,Aeglea Biotherapeutics, 901 S MoPac Expy #250, Austin, Texas 78746, United States
| | - Mickaël Morvan
- Université de Bordeaux, CNRS, CRPP, UMR5031, 115 Avenue Albert Schweitzer, 33600 Pessac, France
| | - Aurélie Vigne
- Université de Bordeaux, CNRS, CRPP, UMR5031, 115 Avenue Albert Schweitzer, 33600 Pessac, France
| | - Jiseok Lim
- School of Mechanical Engineering, Yeungnam University, 280 Daehak-ro, Gyeongsan-si, Gyeongsangbuk-do 38541, Republic of Korea
| | - Philipp Gruner
- Max Planck Institute for Dynamics and Self-Organization, Am Fassberg 17, D37077 Goettingen, Germany
| | - Thomas Beneyton
- Université de Bordeaux, CNRS, CRPP, UMR5031, 115 Avenue Albert Schweitzer, 33600 Pessac, France
| | - Jérémy Vrignon
- Université de Bordeaux, CNRS, CRPP, UMR5031, 115 Avenue Albert Schweitzer, 33600 Pessac, France
| | - Jean-Christophe Baret
- Université de Bordeaux, CNRS, CRPP, UMR5031, 115 Avenue Albert Schweitzer, 33600 Pessac, France.,Institut Universitaire de France, 1 Rue Descartes, 75005 Paris, France
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63
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Fung CW, Chan SN, Wu AR. Microfluidic single-cell analysis-Toward integration and total on-chip analysis. BIOMICROFLUIDICS 2020; 14:021502. [PMID: 32161631 PMCID: PMC7060088 DOI: 10.1063/1.5131795] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/17/2019] [Accepted: 02/25/2020] [Indexed: 06/10/2023]
Abstract
Various types of single-cell analyses are now extensively used to answer many biological questions, and with this growth in popularity, potential drawbacks to these methods are also becoming apparent. Depending on the specific application, workflows can be laborious, low throughput, and run the risk of contamination. Microfluidic designs, with their advantages of being high throughput, low in reaction volume, and compatible with bio-inert materials, have been widely used to improve single-cell workflows in all major stages of single-cell applications, from cell sorting to lysis, to sample processing and readout. Yet, designing an integrated microfluidic chip that encompasses the entire single-cell workflow from start to finish remains challenging. In this article, we review the current microfluidic approaches that cover different stages of processing in single-cell analysis and discuss the prospects and challenges of achieving a full integrated workflow to achieve total single-cell analysis in one device.
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Affiliation(s)
- Cheuk Wang Fung
- Division of Life Science, The Hong Kong University of Science and Technology, Hong Kong, China
| | - Shek Nga Chan
- Division of Life Science, The Hong Kong University of Science and Technology, Hong Kong, China
| | - Angela Ruohao Wu
- Author to whom correspondence should be addressed:. Tel.: +852 3469-2577
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64
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Hung ST, Mukherjee S, Jimenez R. Enrichment of rare events using a multi-parameter high throughput microfluidic droplet sorter. LAB ON A CHIP 2020; 20:834-843. [PMID: 31974539 PMCID: PMC7135947 DOI: 10.1039/c9lc00790c] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
High information content analysis, enrichment, and selection of rare events from a large population are of great importance in biological and biomedical research. The fluorescence lifetime of a fluorophore, a photophysical property which is independent of and complementary to fluorescence intensity, has been incorporated into various imaging and sensing techniques through microscopy, flow cytometry and droplet microfluidics. However, the throughput of fluorescence lifetime activated droplet sorting is orders of magnitude lower than that of fluorescence activated cell sorting, making it unattractive for applications such as directed evolution of enzymes, despite its highly effective compartmentalization of library members. We developed a microfluidic sorter capable of selecting fluorophores based on fluorescence lifetime and brightness at two excitation and emission colors at a maximum droplet rate of 2.5 kHz. We also present a novel selection strategy for efficiently analyzing and/or enriching rare fluorescent members from a large population which capitalizes on the Poisson distribution of analyte encapsulation into droplets. The effectiveness of the droplet sorter and the new selection strategy are demonstrated by enriching rare populations from a ∼108-member site-directed mutagenesis library of fluorescent proteins expressed in bacteria. This selection strategy can in principle be employed on many droplet sorting platforms, and thus can potentially impact broad areas of science where analysis and enrichment of rare events is needed.
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Affiliation(s)
- Sheng-Ting Hung
- JILA, NIST and University of Colorado, Boulder, Colorado 80309, USA.
| | - Srijit Mukherjee
- JILA, NIST and University of Colorado, Boulder, Colorado 80309, USA. and Department of Chemistry, University of Colorado, Boulder, Colorado 80309, USA
| | - Ralph Jimenez
- JILA, NIST and University of Colorado, Boulder, Colorado 80309, USA. and Department of Chemistry, University of Colorado, Boulder, Colorado 80309, USA
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65
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Markel U, Essani KD, Besirlioglu V, Schiffels J, Streit WR, Schwaneberg U. Advances in ultrahigh-throughput screening for directed enzyme evolution. Chem Soc Rev 2020; 49:233-262. [PMID: 31815263 DOI: 10.1039/c8cs00981c] [Citation(s) in RCA: 142] [Impact Index Per Article: 35.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Enzymes are versatile catalysts and their synthetic potential has been recognized for a long time. In order to exploit their full potential, enzymes often need to be re-engineered or optimized for a given application. (Semi-) rational design has emerged as a powerful means to engineer proteins, but requires detailed knowledge about structure function relationships. In turn, directed evolution methodologies, which consist of iterative rounds of diversity generation and screening, can improve an enzyme's properties with virtually no structural knowledge. Current diversity generation methods grant us access to a vast sequence space (libraries of >1012 enzyme variants) that may hide yet unexplored catalytic activities and selectivity. However, the time investment for conventional agar plate or microtiter plate-based screening assays represents a major bottleneck in directed evolution and limits the improvements that are obtainable in reasonable time. Ultrahigh-throughput screening (uHTS) methods dramatically increase the number of screening events per time, which is crucial to speed up biocatalyst design, and to widen our knowledge about sequence function relationships. In this review, we summarize recent advances in uHTS for directed enzyme evolution. We shed light on the importance of compartmentalization to preserve the essential link between genotype and phenotype and discuss how cells and biomimetic compartments can be applied to serve this function. Finally, we discuss how uHTS can inspire novel functional metagenomics approaches to identify natural biocatalysts for novel chemical transformations.
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Affiliation(s)
- Ulrich Markel
- Institute of Biotechnology, RWTH Aachen University, Worringer Weg 3, 52074 Aachen, Germany.
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66
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Haidas D, Napiorkowska M, Schmitt S, Dittrich PS. Parallel Sampling of Nanoliter Droplet Arrays for Noninvasive Protein Analysis in Discrete Yeast Cultivations by MALDI-MS. Anal Chem 2020; 92:3810-3818. [DOI: 10.1021/acs.analchem.9b05235] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
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67
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Teo AJT, Tan SH, Nguyen NT. On-Demand Droplet Merging with an AC Electric Field for Multiple-Volume Droplet Generation. Anal Chem 2020; 92:1147-1153. [PMID: 31763821 DOI: 10.1021/acs.analchem.9b04219] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
We introduce a unique system to achieve on-demand droplet merging and splitting using a perpendicular AC electric field. The working mechanism involves a micropillar to split droplets, followed by electrocoalescence using an AC electric field. Adjusting the parameters of the AC signal and conductivity of the fluid result in different merging regimes. We observed a minimum threshold voltage and a strong influence of the surfactant. We hypothesize that the merging process is caused by dipole-dipole coalescence between the daughter droplets. At the same time, adjustment of the conductivity reveals a shift in the merging regimes and can be explained with an electric circuit diagram. Size-based sorting using this merging phenomenon is subsequently demonstrated, where alternate, single, double, and triple droplets sorting were achieved. The concept presented in this paper is potentially useful for drug dispensing or multivolume digital polymerase chain reaction, as droplets of multiple sizes can be generated simultaneously.
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Affiliation(s)
- Adrian J T Teo
- Queensland Micro- and Nanotechnology Centre , Griffith University , 170 Kessels Road Queensland 4111 , Brisbane , Australia
| | - Say Hwa Tan
- Queensland Micro- and Nanotechnology Centre , Griffith University , 170 Kessels Road Queensland 4111 , Brisbane , Australia
| | - Nam-Trung Nguyen
- Queensland Micro- and Nanotechnology Centre , Griffith University , 170 Kessels Road Queensland 4111 , Brisbane , Australia
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68
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Saygili E, Orakci B, Koprulu M, Demirhan A, Ilhan-Ayisigi E, Kilic Y, Yesil-Celiktas O. Quantitative determination of H 2O 2 for detection of alanine aminotransferase using thin film electrodes. Anal Biochem 2019; 591:113538. [PMID: 31830435 DOI: 10.1016/j.ab.2019.113538] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2019] [Revised: 11/21/2019] [Accepted: 12/07/2019] [Indexed: 11/16/2022]
Abstract
The abnormal concentrations or absence of biomolecules (e.g., proteins) in blood can further be used in diagnosis of a particular pathology at an early stage. Current studies are intensely focusing on the analysis of interaction and detection of biomolecules via point-of-care systems (POCs), allowing miniaturized and parallelized reactions, simultaneously. Recent developments have shown that the collaboration of electrochemical sensing techniques and POCs to overcome challenging problems in health-care settings provides new approaches in diagnosis and treatment of diseases. The aim of this study was to adapt the alanine aminotransferase (ALT) enzyme to the platinum (Pt) thin film electrode system and quantitatively determine the enzyme levels via enzymatically generated H2O2 with differential pulse voltammetry (DPV). A simple potentiostat architecture with expanded sweep range utilizing dual LMP91000 devices was developed and adapted to the needs of the biosensor. In order to calibrate the system, known concentrations of H2O2 were also tested. Moreover, signals associated with the other electroactive species coming from the ALT reaction were eliminated. Resulted potential range has been achieved between +500 mV and +900 mV and the linear range was found to be 0.05 M-0.5 M for H2O2, whereas 5 UL-1 to 120 UL-1 for ALT enzyme.
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Affiliation(s)
- Ecem Saygili
- Department of Bioengineering, Faculty of Engineering, Ege University, 35100, Bornova, Izmir, Turkey
| | - Beyza Orakci
- Department of Bioengineering, Faculty of Engineering, Ege University, 35100, Bornova, Izmir, Turkey
| | - Melisa Koprulu
- Department of Bioengineering, Faculty of Engineering, Ege University, 35100, Bornova, Izmir, Turkey
| | - Alper Demirhan
- Solar Biyoteknoloji Ltd. (SolarBiotec), 35530, Bayrakli, Izmir, Turkey
| | - Esra Ilhan-Ayisigi
- Department of Bioengineering, Faculty of Engineering, Ege University, 35100, Bornova, Izmir, Turkey; Genetic and Bioengineering Department, Faculty of Engineering and Architecture, Ahi Evran University, Kirsehir, Turkey
| | - Yalin Kilic
- Department of Biomedical Engineering, Faculty of Engineering, Izmir University of Economics, 35330, Balcova, Izmir, Turkey
| | - Ozlem Yesil-Celiktas
- Department of Bioengineering, Faculty of Engineering, Ege University, 35100, Bornova, Izmir, Turkey.
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69
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Droplet barcoding: tracking mobile micro-reactors for high-throughput biology. Curr Opin Biotechnol 2019; 60:205-212. [DOI: 10.1016/j.copbio.2019.05.004] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2018] [Accepted: 05/07/2019] [Indexed: 01/09/2023]
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70
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Chiu FWY, Stavrakis S. High-throughput droplet-based microfluidics for directed evolution of enzymes. Electrophoresis 2019; 40:2860-2872. [PMID: 31433062 PMCID: PMC6899980 DOI: 10.1002/elps.201900222] [Citation(s) in RCA: 31] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2019] [Revised: 08/10/2019] [Accepted: 08/12/2019] [Indexed: 01/12/2023]
Abstract
Natural enzymes have evolved over millions of years to allow for their effective operation within specific environments. However, it is significant to note that despite their wide structural and chemical diversity, relatively few natural enzymes have been successfully applied to industrial processes. To address this limitation, directed evolution (DE) (a method that mimics the process of natural selection to evolve proteins toward a user‐defined goal) coupled with droplet‐based microfluidics allows the detailed analysis of millions of enzyme variants on ultra‐short timescales, and thus the design of novel enzymes with bespoke properties. In this review, we aim at presenting the development of DE over the last years and highlighting the most important advancements in droplet‐based microfluidics, made in this context towards the high‐throughput demands of enzyme optimization. Specifically, an overview of the range of microfluidic unit operations available for the construction of DE platforms is provided, focusing on their suitability and benefits for cell‐based assays, as in the case of directed evolution experimentations.
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Affiliation(s)
- Flora W Y Chiu
- Institute for Chemical and Bioengineering, ETH Zürich, Zürich, Switzerland
| | - Stavros Stavrakis
- Institute for Chemical and Bioengineering, ETH Zürich, Zürich, Switzerland
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71
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Horvath DG, Braza S, Moore T, Pan CW, Zhu L, Pak OS, Abbyad P. Sorting by interfacial tension (SIFT): Label-free enzyme sorting using droplet microfluidics. Anal Chim Acta 2019; 1089:108-114. [PMID: 31627807 DOI: 10.1016/j.aca.2019.08.025] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2019] [Revised: 06/06/2019] [Accepted: 08/12/2019] [Indexed: 02/07/2023]
Abstract
Droplet microfluidics has the ability to greatly increase the throughput of screening and sorting of enzymes by carrying reagents in picoliter droplets flowing in inert oils. It was found with the use of a specific surfactant, the interfacial tension of droplets can be very sensitive to droplet pH. This enables the sorting of droplets of different pH when confined droplets encounter a microfabricated trench. The device can be extended to sort enzymes, as a large number of enzymatic reactions lead to the production of an acidic or basic product and a concurrent change in solution pH. The progress of an enzymatic reaction is tracked from the position of a flowing train of droplets. We demonstrate the sorting of esterase isoenzymes based on their enzymatic activity. This label-free technology, that we dub droplet sorting by interfacial tension (SIFT), requires no active components and would have applications for enzyme sorting in high-throughput applications that include enzyme screening and directed evolution of enzymes.
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Affiliation(s)
- Daniel G Horvath
- Department of Chemistry and Biochemistry, Santa Clara University, Santa Clara, CA, 95053, USA
| | - Samuel Braza
- Department of Chemistry and Biochemistry, Santa Clara University, Santa Clara, CA, 95053, USA
| | - Trevor Moore
- Department of Chemistry and Biochemistry, Santa Clara University, Santa Clara, CA, 95053, USA
| | - Ching W Pan
- Department of Chemistry and Biochemistry, Santa Clara University, Santa Clara, CA, 95053, USA
| | - Lailai Zhu
- Department of Mechanical and Aerospace Engineering, Princeton University, Princeton, NJ, 08544, USA; KTH Mechanics, Stockholm, SE-10044, Sweden
| | - On Shun Pak
- Department of Mechanical Engineering, Santa Clara University, Santa Clara, CA, 95053, USA
| | - Paul Abbyad
- Department of Chemistry and Biochemistry, Santa Clara University, Santa Clara, CA, 95053, USA.
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72
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Chung MT, Kurabayashi K, Cai D. Single-cell RT-LAMP mRNA detection by integrated droplet sorting and merging. LAB ON A CHIP 2019; 19:2425-2434. [PMID: 31187105 DOI: 10.1039/c9lc00161a] [Citation(s) in RCA: 27] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/12/2023]
Abstract
Recent advances in transcriptomic analysis at single-cell resolution reveal cell-to-cell heterogeneity in a biological sample with unprecedented resolution. Partitioning single cells in individual micro-droplets and harvesting each cell's mRNA molecules for next-generation sequencing has proven to be an effective method for profiling transcriptomes from a large number of cells at high throughput. However, the assays to recover the full transcriptomes are time-consuming in sample preparation and require expensive reagents and sequencing cost. Many biomedical applications, such as pathogen detection, prefer highly sensitive, reliable and low-cost detection of selected genes. Here, we present a droplet-based microfluidic platform that permits seamless on-chip droplet sorting and merging, which enables completing multi-step reaction assays within a short time. By sequentially adding lysis buffers and reactant mixtures to micro-droplet reactors, we developed a novel workflow of single-cell reverse transcription loop-mediated-isothermal amplification (scRT-LAMP) to quantify specific mRNA expression levels in different cell types within one hour. Including single cell encapsulation, sorting, lysing, reactant addition, and quantitative mRNA detection, the fully on-chip workflow provides a rapid, robust, and high-throughput experimental approach for a wide variety of biomedical studies.
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Affiliation(s)
- Meng Ting Chung
- Department of Mechanical Engineering, University of Michigan, Ann Arbor, MI 48105, USA. and Department of Cell & Developmental Biology, University of Michigan, Ann Arbor, MI 48105, USA.
| | - Katsuo Kurabayashi
- Department of Mechanical Engineering, University of Michigan, Ann Arbor, MI 48105, USA. and Department of Electrical Engineering and Computer Sci., University of Michigan, Ann Arbor, MI 48105, USA
| | - Dawen Cai
- Department of Cell & Developmental Biology, University of Michigan, Ann Arbor, MI 48105, USA. and Biophysics, College of LS&A, University of Michigan, Ann Arbor, MI 48105, USA
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73
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74
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Kasai Y, Sakuma S, Arai F. High-Speed On-Chip Mixing by Microvortex Generated by Controlling Local Jet Flow Using Dual Membrane Pumps. IEEE Robot Autom Lett 2019. [DOI: 10.1109/lra.2019.2921696] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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75
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Schütz SS, Beneyton T, Baret JC, Schneider TM. Rational design of a high-throughput droplet sorter. LAB ON A CHIP 2019; 19:2220-2232. [PMID: 31157806 DOI: 10.1039/c9lc00149b] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
The high-throughput selection of individual droplets is an essential function in droplet-based microfluidics. Fluorescence-activated droplet sorting is achieved using electric fields triggered at rates up to 30 kHz, providing the ultra-high throughput relevant in applications where large libraries of compounds or cells must be analyzed. To achieve such sorting frequencies, electrodes have to create an electric field distribution that generates maximal actuating forces on the droplet while limiting the induced droplet deformation and avoid disintegration. We propose a metric characterizing the performance of an electrode design relative to the theoretical optimum and analyze existing devices using full 3D simulations of the electric fields. By combining parameter optimization with numerical simulation we derive rational design guidelines and propose optimized electrode configurations. When tested experimentally, the optimized design show significantly better performance than the standard designs.
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Affiliation(s)
- Simon S Schütz
- Emergent Complexity in Physical Systems Laboratory (ECPS), École Polytechnique Fédérale de Lausanne (EPFL), Station 9, 1015 Lausanne, Switzerland.
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76
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Cochrane WG, Malone ML, Dang VQ, Cavett V, Satz AL, Paegel BM. Activity-Based DNA-Encoded Library Screening. ACS COMBINATORIAL SCIENCE 2019; 21:425-435. [PMID: 30884226 DOI: 10.1021/acscombsci.9b00037] [Citation(s) in RCA: 48] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Robotic high-throughput compound screening (HTS) and, increasingly, DNA-encoded library (DEL) screening are driving bioactive chemical matter discovery in the postgenomic era. HTS enables activity-based investigation of highly complex targets using static compound libraries. Conversely, DEL grants efficient access to novel chemical diversity, although screening is limited to affinity-based selections. Here, we describe an integrated droplet-based microfluidic circuit that directly screens solid-phase DELs for activity. An example screen of a 67 100-member library for inhibitors of the phosphodiesterase autotaxin yielded 35 high-priority structures for nanomole-scale synthesis and validation (20 active), guiding candidate selection for synthesis at scale (5/5 compounds with IC50 values of 4-10 μM). We further compared activity-based hits with those of an analogous affinity-based DEL selection. This miniaturized screening platform paves the way toward applying DELs to more complex targets (signaling pathways, cellular response) and represents a distributable approach to small molecule discovery.
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Affiliation(s)
| | | | | | | | - Alexander L. Satz
- Roche Pharma Research and Early Development (pRED) Roche Innovation Center Basel F. Hoffman-La Roche Ltd Grenzacherstrasse 124 CH-4070 Basel Switzerland
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77
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Pan CW, Horvath DG, Braza S, Moore T, Lynch A, Feit C, Abbyad P. Sorting by interfacial tension (SIFT): label-free selection of live cells based on single-cell metabolism. LAB ON A CHIP 2019; 19:1344-1351. [PMID: 30849144 PMCID: PMC6456419 DOI: 10.1039/c8lc01328d] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
Selection of live cells from a population is critical in many biological studies and biotechnologies. We present here a novel droplet microfluidic approach that allows for label-free and passive selection of live cells using the glycolytic activity of individual cells. It was observed that with the use of a specific surfactant utilized to stabilize droplet formation, the interfacial tension of droplets was very sensitive to pH. After incubation, cellular lactate release results in droplets containing a live cell to attain a lower pH than other droplets. This enables the sorting of droplets containing live cells when confined droplets flow over a microfabricated trench oriented diagonally with respect to the direction of flow. The technique is demonstrated with human U87 glioblastoma cells for the selection of only droplets containing a live cell while excluding either empty droplets or droplets containing a dead cell. This label-free sorting method, dubbed sorting by interfacial tension (SIFT) presents a new strategy to sort diverse cell types based on metabolic activity.
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Affiliation(s)
- Ching W Pan
- Department of Chemistry and Biochemistry, Santa Clara University, Santa Clara, CA 95053, USA.
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78
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Zhang J, Hassan MR, Rallabandi B, Wang C. Migration of ferrofluid droplets in shear flow under a uniform magnetic field. SOFT MATTER 2019; 15:2439-2446. [PMID: 30801084 DOI: 10.1039/c8sm02522c] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
Manipulation of droplets based on physical properties (e.g., size, interfacial tension, electrical, and mechanical properties) is a critical step in droplet microfluidics. Manipulations based on magnetic fields have several benefits compared to other active methods. While traditional magnetic manipulations require spatially inhomogeneous fields to apply forces, the fast spatial decay of the magnetic field strength from the source makes these techniques difficult to scale up. In this work, we report the observation of lateral migration of ferrofluid (or magnetic) droplets under the combined action of a uniform magnetic field and a pressure-driven flow in a microchannel. While the uniform magnetic field exerts negligible net force on the droplet, the Maxwell stresses deform the droplet to achieve elongated shapes and modulate the orientation relative to the fluid flow. Hydrodynamic interactions between the droplets and the channel walls result in a directional lateral migration. We experimentally study the effects of field strength and direction, and interfacial tension, and use analytical and numerical modeling to understand the lateral migration mechanism.
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Affiliation(s)
- Jie Zhang
- Department of Mechanical and Aerospace Engineering, Missouri University of Science and Technology, 400 W. 13th St., Rolla, Missouri 65409, USA.
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79
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Microfluidics for cell factory and bioprocess development. Curr Opin Biotechnol 2019; 55:95-102. [DOI: 10.1016/j.copbio.2018.08.011] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2018] [Revised: 08/24/2018] [Accepted: 08/31/2018] [Indexed: 12/18/2022]
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80
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Ahmadi F, Samlali K, Vo PQN, Shih SCC. An integrated droplet-digital microfluidic system for on-demand droplet creation, mixing, incubation, and sorting. LAB ON A CHIP 2019; 19:524-535. [PMID: 30633267 DOI: 10.1039/c8lc01170b] [Citation(s) in RCA: 40] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/09/2023]
Abstract
Droplet microfluidics is a technique that has the ability to compartmentalize reactions in sub nano- (or pico-) liter volumes that can potentially enable millions of distinct biological assays to be performed on individual cells. In a typical droplet microfluidic system, droplets are manipulated by pressure-based flows. This has limited the fluidic operations that can be performed in these devices. Digital microfluidics is an alternative microfluidic paradigm with precise control and manipulation over individual droplets. Here, we implement an integrated droplet-digital microfluidic (which we call 'ID2M') system in which common fluidic operations (i.e. droplet generation, cell encapsulation, droplet merging and mixing, droplet trapping and incubation, and droplet sorting) can be performed. With the addition of electrodes, we have been able to create droplets on-demand, tune their volumes on-demand, and merge and mix several droplets to produce a dilution series. Moreover, this device can trap and incubate droplets for 24 h that can consequently be sorted and analyzed in multiple n-ary channels (as opposed to typical binary channels). The ID2M platform has been validated as a robust on-demand screening system by sorting fluorescein droplets of different concentration with an efficiency of ∼96%. The utility of the new system is further demonstrated by culturing and sorting tolerant yeast mutants and wild-type yeast cells in ionic liquid based on their growth profiles. This new platform for both droplet and digital microfluidics has the potential to be used for screening different conditions on-chip and for applications like directed evolution.
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Affiliation(s)
- Fatemeh Ahmadi
- Department of Electrical and Computer Engineering, Concordia University, Montréal, Québec, Canada.
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81
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Abstract
Microfluidics has played a vital role in developing novel methods to investigate biological phenomena at the molecular and cellular level during the last two decades. Microscale engineering of cellular systems is nevertheless a nascent field marked inherently by frequent disruptive advancements in technology such as PDMS-based soft lithography. Viable culture and manipulation of cells in microfluidic devices requires knowledge across multiple disciplines including molecular and cellular biology, chemistry, physics, and engineering. There has been numerous excellent reviews in the past 15 years on applications of microfluidics for molecular and cellular biology including microfluidic cell culture (Berthier et al., 2012; El-Ali, Sorger, & Jensen, 2006; Halldorsson et al., 2015; Kim et al., 2007; Mehling & Tay, 2014; Sackmann et al., 2014; Whitesides, 2006; Young & Beebe, 2010), cell culture models (Gupta et al., 2016; Inamdar & Borenstein, 2011; Meyvantsson & Beebe, 2008), cell secretion (Schrell et al., 2016), chemotaxis (Kim & Wu, 2012; Wu et al., 2013), neuron culture (Millet & Gillette, 2012a, 2012b), drug screening (Dittrich & Manz, 2006; Eribol, Uguz, & Ulgen, 2016; Wu, Huang, & Lee, 2010), cell sorting (Autebert et al., 2012; Bhagat et al., 2010; Gossett et al., 2010; Wyatt Shields Iv, Reyes, & López, 2015), single cell studies (Lecault et al., 2012; Reece et al., 2016; Yin & Marshall, 2012), stem cell biology (Burdick & Vunjak-Novakovic, 2009; Wu et al., 2011; Zhang & Austin, 2012), cell differentiation (Zhang et al., 2017a), systems biology (Breslauer, Lee, & Lee, 2006), 3D cell culture (Huh et al., 2011; Li et al., 2012; van Duinen et al., 2015), spheroids and organoids (Lee et al., 2016; Montanez-Sauri, Beebe, & Sung, 2015; Morimoto & Takeuchi, 2013; Skardal et al., 2016; Young, 2013), organ-on-chip (Bhatia & Ingber, 2014; Esch, Bahinski, & Huh, 2015; Huh et al., 2011; van der Meer & van den Berg, 2012), and tissue engineering (Andersson & Van Den Berg, 2004; Choi et al., 2007; Hasan et al., 2014). In this chapter, we provide an overview of PDMS-based microdevices for microfluidic cell culture. We discuss the advantages and challenges of using PDMS-based soft lithography for microfluidic cell culture and highlight recent progress and future directions in this area.
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Affiliation(s)
- Melikhan Tanyeri
- Biomedical Engineering Program, Duquesne University, Pittsburgh, PA, United States
| | - Savaş Tay
- Institute of Molecular Engineering, University of Chicago, Chicago, IL, United States; Institute of Genomics and Systems Biology, University of Chicago, Chicago, IL, United States.
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82
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Ren L, Yang S, Zhang P, Qu Z, Mao Z, Huang PH, Chen Y, Wu M, Wang L, Li P, Huang TJ. Standing Surface Acoustic Wave (SSAW)-Based Fluorescence-Activated Cell Sorter. SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2018; 14:e1801996. [PMID: 30168662 PMCID: PMC6291339 DOI: 10.1002/smll.201801996] [Citation(s) in RCA: 66] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/24/2018] [Revised: 07/27/2018] [Indexed: 05/15/2023]
Abstract
Microfluidic fluorescence-activated cell sorters (μFACS) have attracted considerable interest because of their ability to identify and separate cells in inexpensive and biosafe ways. Here a high-performance μFACS is presented by integrating a standing surface acoustic wave (SSAW)-based, 3D cell-focusing unit, an in-plane fluorescent detection unit, and an SSAW-based cell-deflection unit on a single chip. Without using sheath flow or precise flow rate control, the SSAW-based cell-focusing technique can focus cells into a single file at a designated position. The tight focusing of cells enables an in-plane-integrated optical detection system to accurately distinguish individual cells of interest. In the acoustic-based cell-deflection unit, a focused interdigital transducer design is utilized to deflect cells from the focused stream within a minimized area, resulting in a high-throughput sorting ability. Each unit is experimentally characterized, respectively, and the integrated SSAW-based FACS is used to sort mammalian cells (HeLa) at different throughputs. A sorting purity of greater than 90% is achieved at a throughput of 2500 events s-1 . The SSAW-based FACS is efficient, fast, biosafe, biocompatible and has a small footprint, making it a competitive alternative to more expensive, bulkier traditional FACS.
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Affiliation(s)
- Liqiang Ren
- Department of Engineering Science and Mechanics, The Pennsylvania State University, University Park, PA, 16802, USA
| | - Shujie Yang
- Department of Mechanical Engineering and Materials Science, Duke University, Durham, NC, 27708, USA
| | - Peiran Zhang
- Department of Mechanical Engineering and Materials Science, Duke University, Durham, NC, 27708, USA
| | - Zhiguo Qu
- Key Laboratory of Thermo-Fluid Science and Engineering, Ministry of Education, Xi'an Jiaotong University, Xi'an, Shaanxi, 710049, China
| | - Zhangming Mao
- Ascent Bio-Nano Technologies, Inc., Research Triangle Park, NC, 27709, USA
| | - Po-Hsun Huang
- Department of Mechanical Engineering and Materials Science, Duke University, Durham, NC, 27708, USA
| | - Yuchao Chen
- Department of Engineering Science and Mechanics, The Pennsylvania State University, University Park, PA, 16802, USA
| | - Mengxi Wu
- Department of Mechanical Engineering and Materials Science, Duke University, Durham, NC, 27708, USA
| | - Lin Wang
- Ascent Bio-Nano Technologies, Inc., Research Triangle Park, NC, 27709, USA
| | - Peng Li
- C. Eugene Bennett Department of Chemistry, West Virginia University, Morgantown, WV, 26506, USA
| | - Tony Jun Huang
- Department of Mechanical Engineering and Materials Science, Duke University, Durham, NC, 27708, USA
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83
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A Cosine Similarity Algorithm Method for Fast and Accurate Monitoring of Dynamic Droplet Generation Processes. Sci Rep 2018; 8:9967. [PMID: 29967430 PMCID: PMC6028520 DOI: 10.1038/s41598-018-28270-8] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2018] [Accepted: 06/20/2018] [Indexed: 11/28/2022] Open
Abstract
Droplet microfluidics has attracted significant interests in functional microcapsule synthesis, pharmaceuticals, fine chemicals, cosmetics and biomedical research. The low variability of performing chemical reactions inside droplets could benefit from improved homogeneity and reproducibility. Therefore, accurate and convenient methods are needed to monitor dynamic droplet generation processes. Here, a novel Cosine Similarity Algorithm (CSA) method was developed to monitor the droplet generation frequency accurately and rapidly. With a microscopic droplet generation video clip captured with a high-speed camera, droplet generation frequency can be computed accurately by calculating the cosine similarities between the frames in the video clip. Four kinds of dynamic droplet generation processes were investigated including (1) a stable condition in a single microfluidic channel, (2) a stable condition in multiple microfluidic channels, (3) a single microfluidic channel with artificial disturbances, and (4) microgel fabrication with or without artificial disturbances. For a video clip with 5,000 frames and a spatial resolution of 512 × 62 pixels, droplet generation frequency up to 4,707.9 Hz can be calculated in less than 1.70 s with an absolute relative calculation error less than 0.08%. Artificial disturbances in droplet generation processes can be precisely determined using the CSA method. This highly effective CSA method could be a powerful tool for further promoting the research of droplet microfluidics.
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84
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Clark IC, Thakur R, Abate AR. Concentric electrodes improve microfluidic droplet sorting. LAB ON A CHIP 2018; 18:710-713. [PMID: 29383336 PMCID: PMC6105269 DOI: 10.1039/c7lc01242j] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/21/2023]
Abstract
Microfluidic droplet sorting allows selection of subpopulations of cells, nucleic acids, and biomolecules with soluble assays. Dielectrophoresis is widely used for sorting because it generates strong forces on droplets, actuates rapidly, and is easy to integrate into microfluidic chips. However, existing device designs apply a short force, limiting the deflection of droplets, and therefore the speed and reliability of sorting. We describe a concentric design that applies a long force, allowing large deflections and increased reliability. We demonstrate the utility of this design by sorting polydisperse emulsions, which are typically difficult to sort with high purity.
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Affiliation(s)
- Iain C Clark
- Department of Bioengineering and Therapeutic Sciences, University of California, San Francisco, San Francisco, CA, USA.
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85
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Sun M, Durkin P, Li J, Toth TL, He X. Label-Free On-Chip Selective Extraction of Cell-Aggregate-Laden Microcapsules from Oil into Aqueous Solution with Optical Sensor and Dielectrophoresis. ACS Sens 2018; 3:410-417. [PMID: 29299919 DOI: 10.1021/acssensors.7b00834] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Microfluidic encapsulation of cells or tissues in biocompatible solidlike hydrogels has wide biomedical applications. However, the microfluidically encapsulated cells/tissues are usually suspended in oil and need to be extracted into aqueous solution for further culture or use. Current extracting techniques are either nonselective for the cell/tissue-laden hydrogel microcapsules or rely on fluorescence labeling of the cells/tissues, which may be undesired for their further culture or use. Here we developed a microelectromechanical system (MEMS) to achieve label-free on-chip selective extraction of cell-aggregate-laden hydrogel microcapsules from oil into aqueous solution. The system includes a microfluidic device, an optical sensor, a dielectrophoretic (DEP) actuator, and microcontrollers. The microfluidic device is for encapsulating cell aggregates in hydrogel microcapsules using the flow-focusing function with microchannels for extracting microcapsules. The optical sensor is to detect the cell aggregates, based on the difference of the optical properties between the cell aggregates and surrounding solution before their encapsulation in hydrogel microcapsules. This strategy is used because the difference in optical property between the cell-aggregate-laden hydrogel microcapsules and empty microcapsules is too small to tell them apart with a commonly used optical sensor. The DEP actuator, which is controlled by the sensor and microcontrollers, is for selectively extracting the targeted hydrogel microcapsules by DEP force. The results indicate this system can achieve selective extraction of cell-aggregate-laden hydrogel microcapsules with ∼100% efficiency without compromising the cell viability, and can improve the purity of the cell-aggregate-laden microcapsules by more than 75 times compared with nonselective extraction.
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Affiliation(s)
- Mingrui Sun
- Department
of Biomedical Engineering, The Ohio State University, Columbus, Ohio 43210, United States
| | - Patrick Durkin
- Department
of Biomedical Engineering, The Ohio State University, Columbus, Ohio 43210, United States
| | - Jianrong Li
- Department of
Veterinary Biosciences, The Ohio State University, Columbus, Ohio 43210, United States
| | - Thomas L. Toth
- Department
of Obstetrics, Gynecology, and Reproductive Biology, Harvard Medical School, Boston, Massachusetts 02115, United States
- Department
of Obstetrics, Gynecology, and Reproductive Biology, Beth Israel Deaconess Medical Center, Boston, Massachusetts 02115, United States
| | - Xiaoming He
- Department
of Biomedical Engineering, The Ohio State University, Columbus, Ohio 43210, United States
- Dorothy
M. Davis Heart and Lung Research Institute, The Ohio State University, Columbus, Ohio 43210, United States
- Comprehensive
Cancer Center, The Ohio State University, Columbus, Ohio 43210, United States
- Fischell
Department of Bioengineering, University of Maryland, College Park, Maryland 20742, United States
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86
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Bunzel HA, Garrabou X, Pott M, Hilvert D. Speeding up enzyme discovery and engineering with ultrahigh-throughput methods. Curr Opin Struct Biol 2018; 48:149-156. [PMID: 29413955 DOI: 10.1016/j.sbi.2017.12.010] [Citation(s) in RCA: 82] [Impact Index Per Article: 13.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2017] [Accepted: 12/26/2017] [Indexed: 01/24/2023]
Abstract
Exploring the sequence space of enzyme catalysts is ultimately a numbers game. Ultrahigh-throughput screening methods for rapid analysis of millions of variants are therefore increasingly important for investigating sequence-function relationships, searching large metagenomic libraries for interesting activities, and accelerating enzyme evolution in the laboratory. Recent applications of such technologies are reviewed here, with a particular focus on the practical benefits of droplet-based microfluidics for the directed evolution of natural and artificial enzymes. Broader implementation of such rapid, cost-effective screening technologies is likely to redefine the way enzymes are studied and engineered for academic and industrial purposes.
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Affiliation(s)
- Hans Adrian Bunzel
- Laboratory of Organic Chemistry, ETH Zurich, Zurich CH-8093, Switzerland
| | - Xavier Garrabou
- Laboratory of Organic Chemistry, ETH Zurich, Zurich CH-8093, Switzerland
| | - Moritz Pott
- Laboratory of Organic Chemistry, ETH Zurich, Zurich CH-8093, Switzerland
| | - Donald Hilvert
- Laboratory of Organic Chemistry, ETH Zurich, Zurich CH-8093, Switzerland.
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87
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Cartier CA, Graybill JR, Bishop KJM. Electric generation and ratcheted transport of contact-charged drops. Phys Rev E 2018; 96:043101. [PMID: 29347598 DOI: 10.1103/physreve.96.043101] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2017] [Indexed: 01/13/2023]
Abstract
We describe a simple microfluidic system that enables the steady generation and efficient transport of aqueous drops using only a constant voltage input. Drop generation is achieved through an electrohydrodynamic dripping mechanism by which conductive drops grow and detach from a grounded nozzle in response to an electric field. The now-charged drops are transported down a ratcheted channel by contact charge electrophoresis powered by the same voltage input used for drop generation. We investigate how the drop size, generation frequency, and transport velocity depend on system parameters such as the liquid viscosity, interfacial tension, applied voltage, and channel dimensions. The observed trends are well explained by a series of scaling analyses that provide insight into the dominant physical mechanisms underlying drop generation and ratcheted transport. We identify the conditions necessary for achieving reliable operation and discuss the various modes of failure that can arise when these conditions are violated. Our results demonstrate that simple electric inputs can power increasingly complex droplet operations with potential opportunities for inexpensive and portable microfluidic systems.
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Affiliation(s)
- Charles A Cartier
- Department of Chemical Engineering, The Pennsylvania State University, University Park, Pennsylvania 16802, USA
| | - Jason R Graybill
- Department of Chemical Engineering, The Pennsylvania State University, University Park, Pennsylvania 16802, USA
| | - Kyle J M Bishop
- Department of Chemical Engineering, Columbia University, New York, New York 10027, USA
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88
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Caen O, Schütz S, Jammalamadaka MSS, Vrignon J, Nizard P, Schneider TM, Baret JC, Taly V. High-throughput multiplexed fluorescence-activated droplet sorting. MICROSYSTEMS & NANOENGINEERING 2018; 4:33. [PMID: 31057921 PMCID: PMC6220162 DOI: 10.1038/s41378-018-0033-2] [Citation(s) in RCA: 38] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/05/2018] [Revised: 07/05/2018] [Accepted: 07/05/2018] [Indexed: 05/02/2023]
Abstract
Fluorescence-activated droplet sorting (FADS) is one of the most important features provided by droplet-based microfluidics. However, to date, it does not allow to compete with the high-throughput multiplexed sorting capabilities offered by flow cytometery. Here, we demonstrate the use of a dielectrophoretic-based FADS, allowing to sort up to five different droplet populations simultaneously. Our system provides means to select droplets of different phenotypes in a single experimental run to separate initially heterogeneous populations. Our experimental results are rationalized with the help of a numerical model of the actuation of droplets in electric fields providing guidelines for the prediction of sorting designs for upscaled or downscaled microsystems.
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Affiliation(s)
- Ouriel Caen
- INSERM UMR-S1147, CNRS SNC5014, Paris Descartes University, Equipe labellisée Ligue Nationale contre le cancer, Paris, France
| | - Simon Schütz
- Emergent Complexity in Physical Systems Laboratory (ECPS), Ecole Polytechnique Fédérale de Lausanne, 1015 Lausanne, Switzerland
| | - M. S. Suryateja Jammalamadaka
- INSERM UMR-S1147, CNRS SNC5014, Paris Descartes University, Equipe labellisée Ligue Nationale contre le cancer, Paris, France
| | - Jérémy Vrignon
- CNRS, University Bordeaux, CRPP, UMR 5031, 115 Avenue Schweitzer, 33600 Pessac, France
| | - Philippe Nizard
- INSERM UMR-S1147, CNRS SNC5014, Paris Descartes University, Equipe labellisée Ligue Nationale contre le cancer, Paris, France
| | - Tobias M. Schneider
- Emergent Complexity in Physical Systems Laboratory (ECPS), Ecole Polytechnique Fédérale de Lausanne, 1015 Lausanne, Switzerland
| | - Jean-Christophe Baret
- CNRS, University Bordeaux, CRPP, UMR 5031, 115 Avenue Schweitzer, 33600 Pessac, France
| | - Valérie Taly
- INSERM UMR-S1147, CNRS SNC5014, Paris Descartes University, Equipe labellisée Ligue Nationale contre le cancer, Paris, France
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89
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Gielen F, Colin PY, Mair P, Hollfelder F. Ultrahigh-Throughput Screening of Single-Cell Lysates for Directed Evolution and Functional Metagenomics. Methods Mol Biol 2018; 1685:297-309. [PMID: 29086317 DOI: 10.1007/978-1-4939-7366-8_18] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
The success of ultrahigh-throughput screening experiments in directed evolution or functional metagenomics strongly depends on the availability of efficient technologies for the quantitative testing of a large number of variants. With advanced robotics, libraries of up to 105 clones can be screened per day as colonies on agar plates or cell lysates in microwell plates, albeit at high cost of capital, manpower and consumables. These cost considerations and the general need for high-throughput make miniaturization of assay volumes attractive. To provide a general solution to maintain genotype-phenotype linkage, biochemical assays have been compartmentalized into water-in-oil droplets. This chapter presents a microfluidic workflow that translates a frequently used screening procedure consisting of cytoplasmic/periplasmic protein expression and cell lysis to the single cell level in water-in-oil droplet compartments. These droplets are sorted based on reaction progress by fluorescence measurements at the picoliter scale.
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Affiliation(s)
- Fabrice Gielen
- Department of Biochemistry, University of Cambridge, 80 Tennis Court Road, Cambridge, CB2 1GA, UK
- Living Systems Institute, University of Exeter, Stocker Road, EX4 4QD, Exeter, UK
| | - Pierre-Yves Colin
- Department of Biochemistry, University of Cambridge, 80 Tennis Court Road, Cambridge, CB2 1GA, UK
- Department of Biochemical Engineering, University College London, Gordon Street, London, WC1H 0AH, UK
| | - Philip Mair
- Department of Biochemistry, University of Cambridge, 80 Tennis Court Road, Cambridge, CB2 1GA, UK
| | - Florian Hollfelder
- Department of Biochemistry, University of Cambridge, 80 Tennis Court Road, Cambridge, CB2 1GA, UK.
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90
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Tenje M, Fornell A, Ohlin M, Nilsson J. Particle Manipulation Methods in Droplet Microfluidics. Anal Chem 2017; 90:1434-1443. [PMID: 29188994 DOI: 10.1021/acs.analchem.7b01333] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
This Feature describes the different particle manipulation techniques available in the droplet microfluidics toolbox to handle particles encapsulated inside droplets and to manipulate whole droplets. We address the advantages and disadvantages of the different techniques to guide new users.
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Affiliation(s)
- Maria Tenje
- Department of Engineering Sciences, Science for Life Laboratory, Uppsala University , Uppsala, 751 21, Sweden.,Department of Biomedical Engineering, Lund University , Lund, 223 63, Sweden
| | - Anna Fornell
- Department of Biomedical Engineering, Lund University , Lund, 223 63, Sweden
| | - Mathias Ohlin
- Department of Engineering Sciences, Uppsala University , Uppsala, 751 21, Sweden
| | - Johan Nilsson
- Department of Biomedical Engineering, Lund University , Lund, 223 63, Sweden
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91
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Qiao Y, Zhao X, Zhu J, Tu R, Dong L, Wang L, Dong Z, Wang Q, Du W. Fluorescence-activated droplet sorting of lipolytic microorganisms using a compact optical system. LAB ON A CHIP 2017; 18:190-196. [PMID: 29227495 DOI: 10.1039/c7lc00993c] [Citation(s) in RCA: 45] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/07/2023]
Abstract
Lipases are ubiquitous enzymes of great physiological significance that have been used extensively in multiple industries. Environmental microorganisms are a major source for the discovery of novel lipases with high catalytic efficiency and selectivity. However, current plate-based screening of lipase-producing strains is time consuming, labour intensive and inefficient. In this study, we developed an ultra-high throughput screening pipeline for lipase-producing strains based on fluorescence-activated droplet sorting (FADS) using a compact optical system that could be easily set up in an alignment-free manner. The pipeline includes droplet generation, droplet incubation, picoinjection of the fluorescence probe, and sorting of droplets with a throughput of 2 × 106 drops per h. We applied the pipeline to screen samples collected from different locations, including sediments from a hot spring in Tibet, soils from the Zoige wetland, contaminated soils from an abandoned oilfield, and a Chinese Daqu starter. In total, we obtained 47 lipase-producing bacterial strains belonging to seven genera, including Staphylococcus, Bacillus, Enterobacter, Serratia, Prolinoborus, Acinetobacter, and Leclercia. We believe that this FADS-based pipeline could be extended to screen various enzymes from the environment, and may find wide applications in breeding of industrial microorganisms.
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Affiliation(s)
- Yuxin Qiao
- State Key Laboratory of Microbial Resources, Institute of Microbiology, Chinese Academy of Sciences, Beijing 100101, China.
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92
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Franco-Gómez A, Thompson AB, Hazel AL, Juel A. Bubble propagation on a rail: a concept for sorting bubbles by size. SOFT MATTER 2017; 13:8684-8697. [PMID: 29125614 DOI: 10.1039/c7sm01478c] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
We demonstrate experimentally that the introduction of a rail, a small height constriction, within the cross-section of a rectangular channel could be used as a robust passive sorting device in two-phase fluid flows. Single air bubbles carried within silicone oil are generally transported on one side of the rail. However, for flow rates marginally larger than a critical value, a narrow band of bubble sizes can propagate (stably) over the rail, while bubbles of other sizes segregate to the side of the rail. The width of this band of bubble sizes increases with flow rate and the size of the most stable bubble can be tuned by varying the rail width. We present a complementary theoretical analysis based on a depth-averaged theory, which is in qualitative agreement with the experiments. The theoretical study reveals that the mechanism relies on a non-trivial interaction between capillary and viscous forces that is fully dynamic, rather than being a simple modification of capillary static solutions.
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Affiliation(s)
- Andrés Franco-Gómez
- Manchester Centre for Nonlinear Dynamics & School of Physics & Astronomy, The University of Manchester, Manchester M13 9PL, UK.
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93
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Cochrane WG, Hackler AL, Cavett VJ, Price AK, Paegel BM. Integrated, Continuous Emulsion Creamer. Anal Chem 2017; 89:13227-13234. [PMID: 29124927 DOI: 10.1021/acs.analchem.7b03070] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Automated and reproducible sample handling is a key requirement for high-throughput compound screening and currently demands heavy reliance on expensive robotics in screening centers. Integrated droplet microfluidic screening processors are poised to replace robotic automation by miniaturizing biochemical reactions to the droplet scale. These processors must generate, incubate, and sort droplets for continuous droplet screening, passively handling millions of droplets with complete uniformity, especially during the key step of sample incubation. Here, we disclose an integrated microfluidic emulsion creamer that packs ("creams") assay droplets by draining away excess oil through microfabricated drain channels. The drained oil coflows with creamed emulsion and then reintroduces the oil to disperse the droplets at the circuit terminus for analysis. Creamed emulsion assay incubation time dispersion was 1.7%, 3-fold less than other reported incubators. The integrated, continuous emulsion creamer (ICEcreamer) was used to miniaturize and optimize measurements of various enzymatic activities (phosphodiesterase, kinase, bacterial translation) under multiple- and single-turnover conditions. Combining the ICEcreamer with current integrated microfluidic DNA-encoded library bead processors eliminates potentially cumbersome instrumentation engineering challenges and is compatible with assays of diverse target class activities commonly investigated in drug discovery.
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Affiliation(s)
- Wesley G Cochrane
- Doctoral Program in the Chemical and Biological Sciences and ‡Department of Chemistry, The Scripps Research Institute , 130 Scripps Way, Jupiter, Florida 33458, United States
| | - Amber L Hackler
- Doctoral Program in the Chemical and Biological Sciences and ‡Department of Chemistry, The Scripps Research Institute , 130 Scripps Way, Jupiter, Florida 33458, United States
| | - Valerie J Cavett
- Doctoral Program in the Chemical and Biological Sciences and ‡Department of Chemistry, The Scripps Research Institute , 130 Scripps Way, Jupiter, Florida 33458, United States
| | - Alexander K Price
- Doctoral Program in the Chemical and Biological Sciences and ‡Department of Chemistry, The Scripps Research Institute , 130 Scripps Way, Jupiter, Florida 33458, United States
| | - Brian M Paegel
- Doctoral Program in the Chemical and Biological Sciences and ‡Department of Chemistry, The Scripps Research Institute , 130 Scripps Way, Jupiter, Florida 33458, United States
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94
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Ung WL, Mutafopulos K, Spink P, Rambach RW, Franke T, Weitz DA. Enhanced surface acoustic wave cell sorting by 3D microfluidic-chip design. LAB ON A CHIP 2017; 17:4059-4069. [PMID: 28994439 DOI: 10.1039/c7lc00715a] [Citation(s) in RCA: 36] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/08/2023]
Abstract
We demonstrate an acoustic wave driven microfluidic cell sorter that combines advantages of multilayer device fabrication with planar surface acoustic wave excitation. We harness the strong vertical component of the refracted acoustic wave to enhance cell actuation by using an asymmetric flow field to increase cell deflection. Precise control of the 3-dimensional flow is realized by topographical structures implemented on the top of the microchannel. We experimentally quantify the effect of the structure dimensions and acoustic parameter. The design attains cell sorting rates and purities approaching those of state of the art fluorescence-activated cell sorters with all the advantages of microfluidic cell sorting.
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Affiliation(s)
- W L Ung
- School of Engineering and Applied Sciences, Harvard University, Cambridge, MA 02138, USA
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95
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Chung MT, Núñez D, Cai D, Kurabayashi K. Deterministic droplet-based co-encapsulation and pairing of microparticles via active sorting and downstream merging. LAB ON A CHIP 2017; 17:3664-3671. [PMID: 28967663 DOI: 10.1039/c7lc00745k] [Citation(s) in RCA: 39] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/16/2023]
Abstract
Co-encapsulation of two distinct particles within microfluidic droplets provides the means to achieve various high-throughput single-cell assays, such as biochemical reactions and cell-cell interactions in small isolated volumes. However, limited by the Poisson statistics, the co-encapsulation rate of the conventional co-flow approach is low even under optimal conditions. Only up to 13.5% of droplets precisely contain a pair of two distinct particles, while the rest, either being empty or encapsulating unpaired particles become wastes. Thus, the low co-encapsulation efficiency makes droplet-based assays impractical in biological applications involving low abundant bioparticles. In this paper, we present a highly promising droplet merging strategy to increase the co-encapsulation efficiency. Our method first enriches droplets exactly encapsulating a single particle via fluorescence or scattering-light activated sorting. Then, two droplets, each with a distinct particle, are precisely one-to-one paired and merged in a novel microwell device. This deterministic approach overcomes the Poisson statistics limitation facing conventional stochastic methods, yielding an up to 90% post-sorting particle capture rate and an overall 88.1% co-encapsulation rate. With its superior single-particle pairing performance, our system provides a promising technological platform to enable highly efficient microdroplet assays.
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Affiliation(s)
- Meng Ting Chung
- Department of Mechanical Engineering, University of Michigan, Ann Arbor, MI 48105, USA.
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96
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Zamir E, Frey C, Weiss M, Antona S, Frohnmayer JP, Janiesch JW, Platzman I, Spatz JP. Reconceptualizing Fluorescence Correlation Spectroscopy for Monitoring and Analyzing Periodically Passing Objects. Anal Chem 2017; 89:11672-11678. [PMID: 28985462 PMCID: PMC5677728 DOI: 10.1021/acs.analchem.7b03108] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
![]()
Fluorescence
correlation spectroscopy (FCS) is a sensitive technique
commonly applied for studying the dynamics of nanoscale-labeled objects
in solution. Current analysis of FCS data is largely based on the
assumption that the labeled objects are stochastically displaced due
to Brownian motion. However, this assumption is often invalid for
microscale objects, since the motion of these objects is dominated
by Stokes drag and settling or rising effects, rather than stochastic
Brownian motion. To utilize the power of FCS for systems with nonstochastic
displacements of objects, the collection and analysis of FCS data
have to be reconceptualized. Here, we extended the applicability of
FCS for the detection and analysis of periodically passing objects.
Toward this end, we implemented droplet-based microfluidics, in which
monodispersed droplets containing fluorescent marker are flowing equally
spaced within microchannels. We show by simulations and experiments
that FCS can sensitively quantify the flow-rates, variability, and
content of rapidly passing droplets. This information can be derived
at high temporal resolution, based on the intensity fluctuations generated
by only 5–10 passing droplets. Moreover, by utilizing the periodicity
of the flowing droplets for noise reduction by averaging, FCS can
monitor accurately the droplets flow even if their fluorescence intensity
is negligible. Hence, extending FCS for periodically passing objects
converts it into a powerful analytical tool for high-throughput droplet-based
microfluidics. Moreover, based on the principles described here, FCS
can be straightforwardly applied for a variety of systems in which
the passing of objects is periodic rather than stochastic.
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Affiliation(s)
- Eli Zamir
- Department of Cellular Biophysics, Max Planck Institute for Medical Research , Jahnstraße 29, D-69120 Heidelberg, Germany.,Department of Biophysical Chemistry, University of Heidelberg , Im Neuenheimer Feld 253, D-69120 Heidelberg, Germany
| | - Christoph Frey
- Department of Cellular Biophysics, Max Planck Institute for Medical Research , Jahnstraße 29, D-69120 Heidelberg, Germany.,Department of Biophysical Chemistry, University of Heidelberg , Im Neuenheimer Feld 253, D-69120 Heidelberg, Germany
| | - Marian Weiss
- Department of Cellular Biophysics, Max Planck Institute for Medical Research , Jahnstraße 29, D-69120 Heidelberg, Germany.,Department of Biophysical Chemistry, University of Heidelberg , Im Neuenheimer Feld 253, D-69120 Heidelberg, Germany
| | - Silvia Antona
- Department of Cellular Biophysics, Max Planck Institute for Medical Research , Jahnstraße 29, D-69120 Heidelberg, Germany.,Department of Biophysical Chemistry, University of Heidelberg , Im Neuenheimer Feld 253, D-69120 Heidelberg, Germany
| | - Johannes P Frohnmayer
- Department of Cellular Biophysics, Max Planck Institute for Medical Research , Jahnstraße 29, D-69120 Heidelberg, Germany.,Department of Biophysical Chemistry, University of Heidelberg , Im Neuenheimer Feld 253, D-69120 Heidelberg, Germany
| | - Jan-Willi Janiesch
- Department of Cellular Biophysics, Max Planck Institute for Medical Research , Jahnstraße 29, D-69120 Heidelberg, Germany.,Department of Biophysical Chemistry, University of Heidelberg , Im Neuenheimer Feld 253, D-69120 Heidelberg, Germany
| | - Ilia Platzman
- Department of Cellular Biophysics, Max Planck Institute for Medical Research , Jahnstraße 29, D-69120 Heidelberg, Germany.,Department of Biophysical Chemistry, University of Heidelberg , Im Neuenheimer Feld 253, D-69120 Heidelberg, Germany
| | - Joachim P Spatz
- Department of Cellular Biophysics, Max Planck Institute for Medical Research , Jahnstraße 29, D-69120 Heidelberg, Germany.,Department of Biophysical Chemistry, University of Heidelberg , Im Neuenheimer Feld 253, D-69120 Heidelberg, Germany
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97
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Gach PC, Iwai K, Kim PW, Hillson NJ, Singh AK. Droplet microfluidics for synthetic biology. LAB ON A CHIP 2017; 17:3388-3400. [PMID: 28820204 DOI: 10.1039/c7lc00576h] [Citation(s) in RCA: 65] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/06/2023]
Abstract
Synthetic biology is an interdisciplinary field that aims to engineer biological systems for useful purposes. Organism engineering often requires the optimization of individual genes and/or entire biological pathways (consisting of multiple genes). Advances in DNA sequencing and synthesis have recently begun to enable the possibility of evaluating thousands of gene variants and hundreds of thousands of gene combinations. However, such large-scale optimization experiments remain cost-prohibitive to researchers following traditional molecular biology practices, which are frequently labor-intensive and suffer from poor reproducibility. Liquid handling robotics may reduce labor and improve reproducibility, but are themselves expensive and thus inaccessible to most researchers. Microfluidic platforms offer a lower entry price point alternative to robotics, and maintain high throughput and reproducibility while further reducing operating costs through diminished reagent volume requirements. Droplet microfluidics have shown exceptional promise for synthetic biology experiments, including DNA assembly, transformation/transfection, culturing, cell sorting, phenotypic assays, artificial cells and genetic circuits.
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Affiliation(s)
- Philip C Gach
- Technology Division, DOE Joint BioEnergy Institute, Emeryville, California 94608, USA
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98
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Abatemarco J, Sarhan MF, Wagner JM, Lin JL, Liu L, Hassouneh W, Yuan SF, Alper HS, Abate AR. RNA-aptamers-in-droplets (RAPID) high-throughput screening for secretory phenotypes. Nat Commun 2017; 8:332. [PMID: 28835641 PMCID: PMC5569033 DOI: 10.1038/s41467-017-00425-7] [Citation(s) in RCA: 85] [Impact Index Per Article: 12.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2017] [Accepted: 06/23/2017] [Indexed: 11/21/2022] Open
Abstract
Synthetic biology and metabolic engineering seek to re-engineer microbes into "living foundries" for the production of high value chemicals. Through a "design-build-test" cycle paradigm, massive libraries of genetically engineered microbes can be constructed and tested for metabolite overproduction and secretion. However, library generation capacity outpaces the rate of high-throughput testing and screening. Well plate assays are flexible but with limited throughput, whereas droplet microfluidic techniques are ultrahigh-throughput but require a custom assay for each target. Here we present RNA-aptamers-in-droplets (RAPID), a method that greatly expands the generality of ultrahigh-throughput microfluidic screening. Using aptamers, we transduce extracellular product titer into fluorescence, allowing ultrahigh-throughput screening of millions of variants. We demonstrate the RAPID approach by enhancing production of tyrosine and secretion of a recombinant protein in Saccharomyces cerevisiae by up to 28- and 3-fold, respectively. Aptamers-in-droplets affords a general approach for evolving microbes to synthesize and secrete value-added chemicals.Screening libraries of genetically engineered microbes for secreted products is limited by the available assay throughput. Here the authors combine aptamer-based fluorescent detection with droplet microfluidics to achieve high throughput screening of yeast strains engineered for enhanced tyrosine or streptavidin production.
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Affiliation(s)
- Joseph Abatemarco
- Department of Chemical Engineering, The University of Texas at Austin, 200 E Dean Keeton St Stop C0400, Austin, Texas, 78712, USA
| | - Maen F Sarhan
- Bioengineering and Therapeutic Sciences, University of California San Francisco, San Francisco, 94158, California, USA
- California Institute for Quantitative Biosciences, University of California San Francisco, San Francisco, 94158, California, USA
| | - James M Wagner
- Department of Chemical Engineering, The University of Texas at Austin, 200 E Dean Keeton St Stop C0400, Austin, Texas, 78712, USA
| | - Jyun-Liang Lin
- Department of Chemical Engineering, The University of Texas at Austin, 200 E Dean Keeton St Stop C0400, Austin, Texas, 78712, USA
| | - Leqian Liu
- Bioengineering and Therapeutic Sciences, University of California San Francisco, San Francisco, 94158, California, USA
- California Institute for Quantitative Biosciences, University of California San Francisco, San Francisco, 94158, California, USA
| | - Wafa Hassouneh
- Bioengineering and Therapeutic Sciences, University of California San Francisco, San Francisco, 94158, California, USA
- California Institute for Quantitative Biosciences, University of California San Francisco, San Francisco, 94158, California, USA
- Chan Zuckerberg Biohub, San Francisco, 94158, California, USA
| | - Shuo-Fu Yuan
- Institute for Cellular and Molecular Biology, The University of Texas at Austin, 2500 Speedway Avenue, Austin, Texas, 78712, USA
| | - Hal S Alper
- Department of Chemical Engineering, The University of Texas at Austin, 200 E Dean Keeton St Stop C0400, Austin, Texas, 78712, USA.
- Institute for Cellular and Molecular Biology, The University of Texas at Austin, 2500 Speedway Avenue, Austin, Texas, 78712, USA.
| | - Adam R Abate
- Bioengineering and Therapeutic Sciences, University of California San Francisco, San Francisco, 94158, California, USA.
- California Institute for Quantitative Biosciences, University of California San Francisco, San Francisco, 94158, California, USA.
- Chan Zuckerberg Biohub, San Francisco, 94158, California, USA.
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99
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MacConnell AB, Paegel BM. Poisson Statistics of Combinatorial Library Sampling Predict False Discovery Rates of Screening. ACS COMBINATORIAL SCIENCE 2017; 19:524-532. [PMID: 28682059 PMCID: PMC5558193 DOI: 10.1021/acscombsci.7b00061] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
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Microfluidic droplet-based
screening of DNA-encoded one-bead-one-compound
combinatorial libraries is a miniaturized, potentially widely distributable
approach to small molecule discovery. In these screens, a microfluidic
circuit distributes library beads into droplets of activity assay
reagent, photochemically cleaves the compound from the bead, then
incubates and sorts the droplets based on assay result for subsequent
DNA sequencing-based hit compound structure elucidation. Pilot experimental
studies revealed that Poisson statistics describe nearly all aspects
of such screens, prompting the development of simulations to understand
system behavior. Monte Carlo screening simulation data showed that
increasing mean library sampling (ε), mean droplet occupancy,
or library hit rate all increase the false discovery rate (FDR). Compounds
identified as hits on k > 1 beads (the replicate k class) were much more likely to be authentic
hits than singletons (k = 1), in agreement with previous
findings. Here, we explain this observation by deriving an equation
for authenticity, which reduces to the product of a library sampling
bias term (exponential in k) and a sampling saturation
term (exponential in ε) setting a threshold that the k-dependent bias must overcome. The equation thus quantitatively
describes why each hit structure’s FDR is based on its k class, and further predicts the feasibility of intentionally
populating droplets with multiple library beads, assaying the micromixtures
for function, and identifying the active members by statistical deconvolution.
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Affiliation(s)
- Andrew B. MacConnell
- Department
of Chemistry and †Doctoral Program in Chemical and Biological
Sciences, The Scripps Research Institute, 130 Scripps Way, Jupiter, Florida 33458, United States
| | - Brian M. Paegel
- Department
of Chemistry and †Doctoral Program in Chemical and Biological
Sciences, The Scripps Research Institute, 130 Scripps Way, Jupiter, Florida 33458, United States
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100
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Caen O, Lu H, Nizard P, Taly V. Microfluidics as a Strategic Player to Decipher Single-Cell Omics? Trends Biotechnol 2017. [DOI: 10.1016/j.tibtech.2017.05.004] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
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