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He Y, Qiao Y, Ding L, Cheng T, Tu J. Recent advances in droplet sequential monitoring methods for droplet sorting. BIOMICROFLUIDICS 2023; 17:061501. [PMID: 37969470 PMCID: PMC10645479 DOI: 10.1063/5.0173340] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/21/2023] [Accepted: 10/23/2023] [Indexed: 11/17/2023]
Abstract
Droplet microfluidics is an attractive technology to run parallel experiments with high throughput and scalability while maintaining the heterogeneous features of individual samples or reactions. Droplet sorting is utilized to collect the desired droplets based on droplet characterization and in-droplet content evaluation. A proper monitoring method is critical in this process, which governs the accuracy and maximum frequency of droplet handling. Until now, numerous monitoring methods have been integrated in the microfluidic devices for identifying droplets, such as optical spectroscopy, mass spectroscopy, electrochemical monitoring, and nuclear magnetic resonance spectroscopy. In this review, we summarize the features of various monitoring methods integrated into droplet sorting workflow and discuss their suitable condition and potential obstacles in use. We aim to provide a systematic introduction and an application guide for choosing and building a droplet monitoring platform.
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Affiliation(s)
- Yukun He
- State Key Laboratory of Digital Medical Engineering, School of Biological Science and Medical Engineering, Southeast University, Nanjing 210096, China
| | - Yi Qiao
- State Key Laboratory of Digital Medical Engineering, School of Biological Science and Medical Engineering, Southeast University, Nanjing 210096, China
| | - Lu Ding
- State Key Laboratory of Digital Medical Engineering, School of Biological Science and Medical Engineering, Southeast University, Nanjing 210096, China
| | - Tianguang Cheng
- State Key Laboratory of Digital Medical Engineering, School of Biological Science and Medical Engineering, Southeast University, Nanjing 210096, China
| | - Jing Tu
- State Key Laboratory of Digital Medical Engineering, School of Biological Science and Medical Engineering, Southeast University, Nanjing 210096, China
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2
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Sun D, Cao F, Yi X, Zhu H, Qi G, Xu W, Xu S. MicroRNA-21 expression in single living cells revealed by fluorescence and SERS dual-response microfluidic droplet platform. LAB ON A CHIP 2022; 22:2165-2172. [PMID: 35522901 DOI: 10.1039/d2lc00096b] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/12/2023]
Abstract
Analysis of single-cell microRNA is essential to reveal cell heterogeneity at the genetic level. It raises a high demand for single-cell analytical methods because single-cell microRNA sequences are highly similar and small in size and feature low-level expression. Herein, SERS and fluorescence imaging technology were introduced into a microfluidic droplet platform to realize direct in situ, nondestructive, and highly sensitive detection of a small number of microRNA-21 (miR-21) in a single intact living cell. A multifunctional plasmonic nanoprobe was designed by decorating a gold nanoparticle with fluorescent dye (ROX)-labeled probe DNA and capture DNA strands. The dual-signal switching of fluorescence turn-off and SERS turn-on of ROX in response to miR-21 achieves highly sensitive and reliable detection of miR-21 in a single cell. The turn-on of SERS signal with a zero background guarantees the sensitivity of the detection. The fluorescence-SERS simultaneous response strategy was able to mutually corroborate the test results, improving the reliability of determining low-level expression of miR-21. SERS combined with encapsulation of microdroplets provides a feasible way to conduct in situ, nondestructive determination of miR-21 secreted by single cells, avoiding cell lysis and tedious time-consuming steps of miR-21 isolation. As a result, the miR-21 expressed by various types of single cells was investigated by fluorescence imaging and the cellular heterogeneity in miR-21 expression was evaluated accurately and quantitatively by SERS. This research would provide important reference information for understanding the effects of miRNAs on cancer diseases at the single-cell level.
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Affiliation(s)
- Dan Sun
- School of Pharmacy, Nantong University, Nantong, Jiangsu 226001, China.
| | - Fanghao Cao
- School of Chemistry and Chemical Engineering, Frontiers Science Center for Transformative Molecules, Shanghai Jiao Tong University, 800 Dongchuan Road, Shanghai 200240, China
| | - Xuan Yi
- School of Pharmacy, Nantong University, Nantong, Jiangsu 226001, China.
| | - Hongyan Zhu
- School of Pharmacy, Nantong University, Nantong, Jiangsu 226001, China.
| | - Guohua Qi
- State Key Laboratory of Electroanalytical Chemistry, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun 130022, Jilin, P. R. China
| | - Weiqing Xu
- State Key Laboratory of Supramolecular Structure and Materials, Institute of Theoretical Chemistry, College of Chemistry, Jilin University, Changchun 130012, P. R. China
| | - Shuping Xu
- State Key Laboratory of Supramolecular Structure and Materials, Institute of Theoretical Chemistry, College of Chemistry, Jilin University, Changchun 130012, P. R. China
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3
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Advances in droplet microfluidics for SERS and Raman analysis. Biosens Bioelectron 2022; 198:113822. [PMID: 34836710 DOI: 10.1016/j.bios.2021.113822] [Citation(s) in RCA: 14] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2021] [Revised: 11/14/2021] [Accepted: 11/17/2021] [Indexed: 12/14/2022]
Abstract
Raman spectroscopy can realize qualitative and quantitative characterization, and surface-enhanced Raman spectroscopy (SERS) can further enhance its detection sensitivity. In combination with droplet microfluidics, some significant but insurmountable limitations of SERS and Raman spectroscopy can be overcome to some extent, thus improving their detection capability and extending their application. During the past decade, these systems have constantly developed and demonstrated a great potential in more applications, but there is no new review systematically summarizing the droplet microfluidics-based Raman and SERS analysis system since the first related review was published in 2011. Thus, there is a great need for a new review to summarize the advances. In this review, we focus on droplet microfluidics-based Raman and SERS analysis, and summarize two mainstream research directions on this topic up to now. The one is SERS or Raman detection in the moving droplet microreactors, including analysis of molecules, single cells and chemical reaction processes. The other one is SERS active microparticle fabrication via microfluidic droplet templates covering polymer matrix and photonic crystal microparticles. We also comment on the advantages, disadvantage and correlation resolution of droplet microfluidics for SERS or Raman. Finally, we summarize these systems and illustrate our perspectives for future research directions in this field.
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4
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Ren R, Sun M, Goel P, Cai S, Kotov NA, Kuang H, Xu C, Ivanov AP, Edel JB. Single-Molecule Binding Assay Using Nanopores and Dimeric NP Conjugates. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2021; 33:e2103067. [PMID: 34323323 DOI: 10.1002/adma.202103067] [Citation(s) in RCA: 22] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/22/2021] [Revised: 05/25/2021] [Indexed: 06/13/2023]
Abstract
The ability to measure biomarkers, both specifically and selectively at the single-molecule level in biological fluids, has the potential to transform the diagnosis, monitoring, and therapeutic intervention of diseases. The use of nanopores has been gaining prominence in this area, not only for sequencing but more recently in screening applications. The selectivity of nanopore sensing can be substantially improved with the use of labels, but substantial challenges remain, especially when trying to differentiate between bound from unbound targets. Here highly sensitive and selective molecular probes made from nanoparticles (NPs) that self-assemble and dimerize upon binding to a biological target are designed. It is shown that both single and paired NPs can be successfully resolved and detected at the single-molecule nanopore sensing and can be used for applications such as antigen/antibody detection and microRNA (miRNA) sequence analysis. It is expected that such technology will contribute significantly to developing highly sensitive and selective strategies for the diagnosis and screening of diseases without the need for sample processing or amplification while requiring minimal sample volume.
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Affiliation(s)
- Ren Ren
- Department of Chemistry, Molecular Science Research Hub, Imperial College London, White City Campus, 82 Wood Lane, London, W12 0BZ, UK
| | - Maozhong Sun
- Key Lab of Synthetic and Biological Colloids, Ministry of Education, State Key Lab of Food Science and Technology, International Joint Research Laboratory for Biointerface and Biodetection, School of Food Science and Technology, Jiangnan University, Wuxi, Jiangsu, 214122, P. R. China
| | - Pratibha Goel
- Department of Chemistry, Molecular Science Research Hub, Imperial College London, White City Campus, 82 Wood Lane, London, W12 0BZ, UK
| | - Shenglin Cai
- Department of Chemistry, Molecular Science Research Hub, Imperial College London, White City Campus, 82 Wood Lane, London, W12 0BZ, UK
| | - Nicholas A Kotov
- Department of Chemical Engineering, University of Michigan, Ann Arbor, MI, 48109, USA
- Department of Materials Science and Engineering, University of Michigan, Ann Arbor, MI, 48109, USA
| | - Hua Kuang
- Key Lab of Synthetic and Biological Colloids, Ministry of Education, State Key Lab of Food Science and Technology, International Joint Research Laboratory for Biointerface and Biodetection, School of Food Science and Technology, Jiangnan University, Wuxi, Jiangsu, 214122, P. R. China
| | - Chuanlai Xu
- Key Lab of Synthetic and Biological Colloids, Ministry of Education, State Key Lab of Food Science and Technology, International Joint Research Laboratory for Biointerface and Biodetection, School of Food Science and Technology, Jiangnan University, Wuxi, Jiangsu, 214122, P. R. China
| | - Aleksandar P Ivanov
- Department of Chemistry, Molecular Science Research Hub, Imperial College London, White City Campus, 82 Wood Lane, London, W12 0BZ, UK
| | - Joshua B Edel
- Department of Chemistry, Molecular Science Research Hub, Imperial College London, White City Campus, 82 Wood Lane, London, W12 0BZ, UK
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5
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Probst J, Howes P, Arosio P, Stavrakis S, deMello A. Broad-Band Spectrum, High-Sensitivity Absorbance Spectroscopy in Picoliter Volumes. Anal Chem 2021; 93:7673-7681. [PMID: 34009952 DOI: 10.1021/acs.analchem.1c00587] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Picoliter-volume droplets within segmented flows can be probed in a rapid and efficient manner using optical detection methods. To date, however, most detection schemes for droplet content analysis have relied on the use of time-integrated fluorescence measurements. Despite its undoubted utility, the implementation of absorbance-based detectors is particularly challenging due to the reduced optical path lengths that are characteristic of microfluidic systems and deleterious scattering at droplet-oil interfaces. Unsurprisingly, efforts to develop sensitive absorbance-based detection schemes for the interrogation of rapidly moving droplets have primarily focused on ensuring adequate analytical sensitivity and, to date, have been exclusively limited to single-wavelength measurements. To address this limitation, and expand the information content associated with absorbance measurements on-chip, we herein describe a detection scheme for the extraction of broad-band absorbance spectra from pL-volume droplets with high sensitivity. The combination of a confocal optical system (that confines incident light to a reduced detection volume) and a postprocessing algorithm (that effectively removes the contribution of the carrier oil from the extracted spectra) engenders significant improvements in signal-to-noise ratios. Our system is initially calibrated by acquiring absorbance spectra from aqueous solutions of fluorescein isothiocyanate. These measurements confirm both excellent linearity over the studied range (from 0 to 100 μM) and a concentration limit of detection of 800 nM. The methodology is then used to monitor the salt-induced aggregation of gold nanoparticles with millisecond time resolution. This approach for small-volume absorbance spectroscopy allows for both high-throughput and high-information content measurements in subnanoliter volumes and will be highly desirable in a wide variety of bioanalytical applications where sensitivity and throughput are priorities.
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Affiliation(s)
- Julie Probst
- Institute for Chemical and Bioengineering, Department of Chemistry and Applied Biosciences, ETH Zürich, Vladimir Prelog Weg 1, 8093 Zürich, Switzerland
| | - Philip Howes
- Institute for Chemical and Bioengineering, Department of Chemistry and Applied Biosciences, ETH Zürich, Vladimir Prelog Weg 1, 8093 Zürich, Switzerland
| | - Paolo Arosio
- Institute for Chemical and Bioengineering, Department of Chemistry and Applied Biosciences, ETH Zürich, Vladimir Prelog Weg 1, 8093 Zürich, Switzerland
| | - Stavros Stavrakis
- Institute for Chemical and Bioengineering, Department of Chemistry and Applied Biosciences, ETH Zürich, Vladimir Prelog Weg 1, 8093 Zürich, Switzerland
| | - Andrew deMello
- Institute for Chemical and Bioengineering, Department of Chemistry and Applied Biosciences, ETH Zürich, Vladimir Prelog Weg 1, 8093 Zürich, Switzerland
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6
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Pärnamets K, Pardy T, Koel A, Rang T, Scheler O, Le Moullec Y, Afrin F. Optical Detection Methods for High-Throughput Fluorescent Droplet Microflow Cytometry. MICROMACHINES 2021; 12:mi12030345. [PMID: 33807031 PMCID: PMC8004903 DOI: 10.3390/mi12030345] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/25/2021] [Revised: 03/18/2021] [Accepted: 03/19/2021] [Indexed: 11/16/2022]
Abstract
High-throughput microflow cytometry has become a focal point of research in recent years. In particular, droplet microflow cytometry (DMFC) enables the analysis of cells reacting to different stimuli in chemical isolation due to each droplet acting as an isolated microreactor. Furthermore, at high flow rates, the droplets allow massive parallelization, further increasing the throughput of droplets. However, this novel methodology poses unique challenges related to commonly used fluorometry and fluorescent microscopy techniques. We review the optical sensor technology and light sources applicable to DMFC, as well as analyze the challenges and advantages of each option, primarily focusing on electronics. An analysis of low-cost and/or sufficiently compact systems that can be incorporated into portable devices is also presented.
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Affiliation(s)
- Kaiser Pärnamets
- Thomas Johann Seebeck Department of Electronics, Tallinn University of Technology, 19086 Tallinn, Estonia; (A.K.); (T.R.); (Y.L.M.); (F.A.)
- Correspondence:
| | - Tamas Pardy
- Department of Chemistry and Biotechnology, Tallinn University of Technology, 19086 Tallinn, Estonia; (T.P.); (O.S.)
| | - Ants Koel
- Thomas Johann Seebeck Department of Electronics, Tallinn University of Technology, 19086 Tallinn, Estonia; (A.K.); (T.R.); (Y.L.M.); (F.A.)
| | - Toomas Rang
- Thomas Johann Seebeck Department of Electronics, Tallinn University of Technology, 19086 Tallinn, Estonia; (A.K.); (T.R.); (Y.L.M.); (F.A.)
| | - Ott Scheler
- Department of Chemistry and Biotechnology, Tallinn University of Technology, 19086 Tallinn, Estonia; (T.P.); (O.S.)
| | - Yannick Le Moullec
- Thomas Johann Seebeck Department of Electronics, Tallinn University of Technology, 19086 Tallinn, Estonia; (A.K.); (T.R.); (Y.L.M.); (F.A.)
| | - Fariha Afrin
- Thomas Johann Seebeck Department of Electronics, Tallinn University of Technology, 19086 Tallinn, Estonia; (A.K.); (T.R.); (Y.L.M.); (F.A.)
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7
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Tadesse LF, Safir F, Ho CS, Hasbach X, Khuri-Yakub BP, Jeffrey SS, Saleh AAE, Dionne J. Toward rapid infectious disease diagnosis with advances in surface-enhanced Raman spectroscopy. J Chem Phys 2021; 152:240902. [PMID: 32610995 DOI: 10.1063/1.5142767] [Citation(s) in RCA: 26] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
In a pandemic era, rapid infectious disease diagnosis is essential. Surface-enhanced Raman spectroscopy (SERS) promises sensitive and specific diagnosis including rapid point-of-care detection and drug susceptibility testing. SERS utilizes inelastic light scattering arising from the interaction of incident photons with molecular vibrations, enhanced by orders of magnitude with resonant metallic or dielectric nanostructures. While SERS provides a spectral fingerprint of the sample, clinical translation is lagged due to challenges in consistency of spectral enhancement, complexity in spectral interpretation, insufficient specificity and sensitivity, and inefficient workflow from patient sample collection to spectral acquisition. Here, we highlight the recent, complementary advances that address these shortcomings, including (1) design of label-free SERS substrates and data processing algorithms that improve spectral signal and interpretability, essential for broad pathogen screening assays; (2) development of new capture and affinity agents, such as aptamers and polymers, critical for determining the presence or absence of particular pathogens; and (3) microfluidic and bioprinting platforms for efficient clinical sample processing. We also describe the development of low-cost, point-of-care, optical SERS hardware. Our paper focuses on SERS for viral and bacterial detection, in hopes of accelerating infectious disease diagnosis, monitoring, and vaccine development. With advances in SERS substrates, machine learning, and microfluidics and bioprinting, the specificity, sensitivity, and speed of SERS can be readily translated from laboratory bench to patient bedside, accelerating point-of-care diagnosis, personalized medicine, and precision health.
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Affiliation(s)
- Loza F Tadesse
- Department of Bioengineering, Stanford University School of Medicine and School of Engineering, Stanford, California 94305, USA
| | - Fareeha Safir
- Department of Mechanical Engineering, Stanford University School of Engineering, Stanford, California 94305, USA
| | - Chi-Sing Ho
- Department of Applied Physics, Stanford University School of Humanities and Sciences, Stanford, California 94305, USA
| | - Ximena Hasbach
- Department of Materials Science and Engineering, Stanford University School of Engineering, Stanford, California 94305, USA
| | - Butrus Pierre Khuri-Yakub
- Department of Electrical Engineering, Stanford University School of Engineering, Stanford, California 94305, USA
| | - Stefanie S Jeffrey
- Department of Surgery, Stanford University School of Medicine, Stanford, California 94305, USA
| | - Amr A E Saleh
- Department of Materials Science and Engineering, Stanford University School of Engineering, Stanford, California 94305, USA
| | - Jennifer Dionne
- Department of Materials Science and Engineering, Stanford University School of Engineering, Stanford, California 94305, USA
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8
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Method for Passive Droplet Sorting after Photo-Tagging. MICROMACHINES 2020; 11:mi11110964. [PMID: 33126559 PMCID: PMC7692103 DOI: 10.3390/mi11110964] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/21/2020] [Revised: 10/22/2020] [Accepted: 10/26/2020] [Indexed: 12/16/2022]
Abstract
We present a method to photo-tag individual microfluidic droplets for latter selection by passive sorting. The use of a specific surfactant leads to the interfacial tension to be very sensitive to droplet pH. The photoexcitation of droplets containing a photoacid, pyranine, leads to a decrease in droplet pH. The concurrent increase in droplet interfacial tension enables the passive selection of irradiated droplets. The technique is used to select individual droplets within a droplet array as illuminated droplets remain in the wells while other droplets are eluted by the flow of the external oil. This method was used to select droplets in an array containing cells at a specific stage of apoptosis. The technique is also adaptable to continuous-flow sorting. By passing confined droplets over a microfabricated trench positioned diagonally in relation to the direction of flow, photo-tagged droplets were directed toward a different chip exit based on their lateral movement. The technique can be performed on a conventional fluorescence microscope and uncouples the observation and selection of droplets, thus enabling the selection on a large variety of signals, or based on qualitative user-defined features.
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9
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Kempa EE, Smith CA, Li X, Bellina B, Richardson K, Pringle S, Galman JL, Turner NJ, Barran PE. Coupling Droplet Microfluidics with Mass Spectrometry for Ultrahigh-Throughput Analysis of Complex Mixtures up to and above 30 Hz. Anal Chem 2020; 92:12605-12612. [PMID: 32786490 PMCID: PMC8009470 DOI: 10.1021/acs.analchem.0c02632] [Citation(s) in RCA: 36] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
![]()
High-
and ultrahigh-throughput label-free sample analysis is required
by many applications, extending from environmental monitoring to drug
discovery and industrial biotechnology. HTS methods predominantly
are based on a targeted workflow, which can limit their scope. Mass
spectrometry readily provides chemical identity and abundance for
complex mixtures, and here, we use microdroplet generation microfluidics
to supply picoliter aliquots for analysis at rates up to and including
33 Hz. This is demonstrated for small molecules, peptides, and proteins
up to 66 kDa on three commercially available mass spectrometers from
salty solutions to mimic cellular environments. Designs for chip-based
interfaces that permit this coupling are presented, and the merits
and challenges of these interfaces are discussed. On an Orbitrap platform
droplet infusion rates of 6 Hz are used for analysis of cytochrome c, on a DTIMS Q-TOF similar rates were obtained, and on
a TWIMS Q-TOF utilizing IM-MS software rates up to 33 Hz are demonstrated.
The potential of this approach is demonstrated with proof of concept
experiments on crude mixtures including egg white, unpurified recombinant
protein, and a biotransformation supernatant.
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Affiliation(s)
- Emily E Kempa
- Michael Barber Centre for Collaborative Mass Spectrometry, Manchester Institute of Biotechnology, Manchester M1 7DN, United Kingdom
| | - Clive A Smith
- Sphere Fluidics Limited, McClintock Building, Suite 7, Granta Park, Great Abington, Cambridge CB21 6GP, United Kingdom
| | - Xin Li
- Sphere Fluidics Limited, McClintock Building, Suite 7, Granta Park, Great Abington, Cambridge CB21 6GP, United Kingdom
| | - Bruno Bellina
- Michael Barber Centre for Collaborative Mass Spectrometry, Manchester Institute of Biotechnology, Manchester M1 7DN, United Kingdom
| | - Keith Richardson
- Waters Corporation, Stamford Avenue, Altrincham Road, Wilmslow SK9 4AX, United Kingdom
| | - Steven Pringle
- Waters Corporation, Stamford Avenue, Altrincham Road, Wilmslow SK9 4AX, United Kingdom
| | - James L Galman
- Manchester Institute of Biotechnology, Manchester M1 7DN, United Kingdom
| | - Nicholas J Turner
- Manchester Institute of Biotechnology, Manchester M1 7DN, United Kingdom
| | - Perdita E Barran
- Michael Barber Centre for Collaborative Mass Spectrometry, Manchester Institute of Biotechnology, Manchester M1 7DN, United Kingdom
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10
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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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11
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Mendl A, Köhler JM, Bošković D, Löbbecke S. Novel SERS-based process analysis for label-free segmented flow screenings. LAB ON A CHIP 2020; 20:2364-2371. [PMID: 32495800 DOI: 10.1039/d0lc00367k] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
In microfluidic segmented flow processes label-free analytical techniques like surface enhanced Raman spectroscopy (SERS) can reveal the chemical composition of the individual droplet contents. The SERS system developed in this work enables a simple connection to micro segmented flow processes through miniaturization. The concept is based on the parallelization of silver/polyacrylamide composite SERS spots on a carrier plate on which the segments are deposited. The transfer of the segments allows an easy connection to existing flow processes and provides optimal conditions for Raman measurements using miniaturized spectrometers. The preparation of the SERS polymer composite was optimized in terms of the silver content in the polymer matrix to obtain a high SERS signal. The performance and long-term stability of the polymer have been successfully demonstrated. The deamination of adenine with sodium nitrite to hypoxanthine was chosen as a case study to demonstrate the capability of the novel SERS-based process analysis. A sequence of approximately one hundred segments in combination with a gradient of the nitrite concentration (0 to 0.4 mol L-1) was generated at two temperatures. The concentration of adenine and hypoxanthine were determined by using a multivariate calibration model, since the Raman spectra of both substances are overlapping. It was shown that the conversion of adenine is increased with higher nitrite concentration and temperature. A conversion of 35% was obtained at 50 °C and a conversion of 60% at 80 °C, respectively.
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Affiliation(s)
- Alexander Mendl
- Fraunhofer Institute for Chemical Technology, Pfinztal 76327, Germany.
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12
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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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13
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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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14
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Witkowska D, Rowińska-Żyrek M. Biophysical approaches for the study of metal-protein interactions. J Inorg Biochem 2019; 199:110783. [PMID: 31349072 DOI: 10.1016/j.jinorgbio.2019.110783] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2019] [Revised: 07/10/2019] [Accepted: 07/15/2019] [Indexed: 12/17/2022]
Abstract
Protein-protein interactions play important roles for a variety of cell functions, often involving metal ions; in fact, metal-ion binding mediates and regulates the activity of a wide range of biomolecules. Enlightening all of the specific features of metal-protein and metal-mediated protein-protein interactions can be a very challenging task; a detailed knowledge of the thermodynamic and spectroscopic parameters and the structural changes of the protein is normally required. For this purpose, many experimental techniques are employed, embracing all fields of Analytical and Bioinorganic Chemistry. In addition, the use of peptide models, reproducing the primary sequence of the metal-binding sites, is also proved to be useful. In this paper, a review of the most useful techniques for studying ligand-protein interactions with a special emphasis on metal-protein interactions is provided, with a critical summary of their strengths and limitations.
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Affiliation(s)
- Danuta Witkowska
- Public Higher Medical Professional School in Opole, Katowicka 68, 45060 Opole, Poland.
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15
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Höhn EM, Panneerselvam R, Das A, Belder D. Raman Spectroscopic Detection in Continuous Microflow Using a Chip-Integrated Silver Electrode as an Electrically Regenerable Surface-Enhanced Raman Spectroscopy Substrate. Anal Chem 2019; 91:9844-9851. [DOI: 10.1021/acs.analchem.9b01514] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Affiliation(s)
- Eva-Maria Höhn
- Institut für Analytische Chemie, Universität Leipzig, Johannisallee 29, Leipzig 04103, Germany
| | | | - Anish Das
- Institut für Analytische Chemie, Universität Leipzig, Johannisallee 29, Leipzig 04103, Germany
| | - Detlev Belder
- Institut für Analytische Chemie, Universität Leipzig, Johannisallee 29, Leipzig 04103, Germany
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16
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Nesakumar N, Kesavan S, Li CZ, Alwarappan S. Microfluidic Electrochemical Devices for Biosensing. JOURNAL OF ANALYSIS AND TESTING 2019. [DOI: 10.1007/s41664-019-0083-y] [Citation(s) in RCA: 29] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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17
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Sun D, Cao F, Cong L, Xu W, Chen Q, Shi W, Xu S. Cellular heterogeneity identified by single-cell alkaline phosphatase (ALP) via a SERRS-microfluidic droplet platform. LAB ON A CHIP 2019; 19:335-342. [PMID: 30566170 DOI: 10.1039/c8lc01006d] [Citation(s) in RCA: 36] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
Alkaline phosphatase (ALP) is a useful indicator for disease state diagnosis and clinical outcome. Investigation of ALP expression among cells is still challenging since ALP expression in a single cell is too low to be detectable. In our work, an ultrasensitive, high-throughput analytical method was applied for ALP determination in a single cell by using a surface-enhanced resonance Raman scattering (SERRS)-based microfluidic droplet technique. An ALP catalyzed substrate (5-bromo-4-chloro-3-indolyl phosphate, BCIP) was used to evaluate ALP activity in the cell within one droplet. When BCIP was incubated with cells, ALP can catalyze a hydrolysis reaction of colorless BCIP and oxidize the intermediate compound to form blue 5,5'-dibromo-4,4'-dichloro-1H,1H-[2,2']biindolylidene-3,3'-dione (BCI), which is a resonant Raman-active species. The encapsulation of BCI in droplets is favorable for detecting extremely low levels of molecules due to an accumulation effect along with reaction time. The ALP concentration as low as 1.0 × 10-15 M can be successfully detected in a uniform droplet. In addition, cellular heterogeneity profiled by ALP expression on single-cell resolution was monitored with this SERRS-based microfluidic droplet technique. Ultrasensitive determination of ALP secreted from individual cells can help us to understand cell-to-cell heterogeneity.
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Affiliation(s)
- Dan Sun
- State Key Laboratory of Supramolecular Structure and Materials, Institute of Theoretical Chemistry, Jilin University, Changchun 130012, PR China.
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18
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Sun D, Cao F, Xu W, Chen Q, Shi W, Xu S. Ultrasensitive and Simultaneous Detection of Two Cytokines Secreted by Single Cell in Microfluidic Droplets via Magnetic-Field Amplified SERS. Anal Chem 2019; 91:2551-2558. [DOI: 10.1021/acs.analchem.8b05892] [Citation(s) in RCA: 48] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Dan Sun
- State Key Laboratory of Supramolecular Structure and Materials, Institute of Theoretical Chemistry, Jilin University, Changchun 130012, PR China
| | - Fanghao Cao
- State Key Laboratory of Supramolecular Structure and Materials, Institute of Theoretical Chemistry, Jilin University, Changchun 130012, PR China
- School of Chemical Engineering and New Energy Materials, Zhuhai College, Jilin University, Zhuhai 519041, PR China
| | - Weiqing Xu
- State Key Laboratory of Supramolecular Structure and Materials, Institute of Theoretical Chemistry, Jilin University, Changchun 130012, PR China
| | - Qidan Chen
- State Key Laboratory of Supramolecular Structure and Materials, Institute of Theoretical Chemistry, Jilin University, Changchun 130012, PR China
- School of Chemical Engineering and New Energy Materials, Zhuhai College, Jilin University, Zhuhai 519041, PR China
| | - Wei Shi
- Key Lab for Molecular Enzymology and Engineering of Ministry of Education, Jilin University, Changchun 130012, PR China
| | - Shuping Xu
- State Key Laboratory of Supramolecular Structure and Materials, Institute of Theoretical Chemistry, Jilin University, Changchun 130012, PR China
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19
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Kaushik AM, Hsieh K, Wang TH. Droplet microfluidics for high-sensitivity and high-throughput detection and screening of disease biomarkers. WILEY INTERDISCIPLINARY REVIEWS. NANOMEDICINE AND NANOBIOTECHNOLOGY 2018; 10:e1522. [PMID: 29797414 PMCID: PMC6185786 DOI: 10.1002/wnan.1522] [Citation(s) in RCA: 44] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/15/2017] [Revised: 03/02/2018] [Accepted: 03/10/2018] [Indexed: 12/17/2022]
Abstract
Biomarkers are nucleic acids, proteins, single cells, or small molecules in human tissues or biological fluids whose reliable detection can be used to confirm or predict disease and disease states. Sensitive detection of biomarkers is therefore critical in a variety of applications including disease diagnostics, therapeutics, and drug screening. Unfortunately for many diseases, low abundance of biomarkers in human samples and low sample volumes render standard benchtop platforms like 96-well plates ineffective for reliable detection and screening. Discretization of bulk samples into a large number of small volumes (fL-nL) via droplet microfluidic technology offers a promising solution for high-sensitivity and high-throughput detection and screening of biomarkers. Several microfluidic strategies exist for high-throughput biomarker digitization into droplets, and these strategies have been utilized by numerous droplet platforms for nucleic acid, protein, and single-cell detection and screening. While the potential of droplet-based platforms has led to burgeoning interest in droplets, seamless integration of sample preparation technologies and automation of platforms from biological sample to answer remain critical components that can render these platforms useful in the clinical setting in the near future. This article is categorized under: Diagnostic Tools > Biosensing Diagnostic Tools > Diagnostic Nanodevices Therapeutic Approaches and Drug Discovery > Emerging Technologies Therapeutic Approaches and Drug Discovery > Nanomedicine for Infectious Disease.
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Affiliation(s)
| | - Kuangwen Hsieh
- Department of Mechanical Engineering, Johns Hopkins University
| | - Tza-Huei Wang
- Department of Mechanical Engineering, Department of Biomedical Engineering, Johns Hopkins University
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20
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Galaverna R, Ribessi RL, Rohwedder JJR, Pastre JC. Coupling Continuous Flow Microreactors to MicroNIR Spectroscopy: Ultracompact Device for Facile In-Line Reaction Monitoring. Org Process Res Dev 2018. [DOI: 10.1021/acs.oprd.8b00060] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Renan Galaverna
- Institute of Chemistry, University of Campinas - UNICAMP, P.O. Box 6154, 13083-970 Campinas-SP, Brazil
| | - Rafael L. Ribessi
- Institute of Chemistry, University of Campinas - UNICAMP, P.O. Box 6154, 13083-970 Campinas-SP, Brazil
| | - Jarbas J. R. Rohwedder
- Institute of Chemistry, University of Campinas - UNICAMP, P.O. Box 6154, 13083-970 Campinas-SP, Brazil
| | - Julio C. Pastre
- Institute of Chemistry, University of Campinas - UNICAMP, P.O. Box 6154, 13083-970 Campinas-SP, Brazil
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21
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Abstract
Droplet microfluidic systems have evolved as fluidic platforms that use much less sample volume and provide high throughput for biochemical analysis compared to conventional microfluidic devices. The variety of droplet fluidic applications triggered several detection techniques to be applied for analysis of droplets. In this review, we focus on label-free droplet detection techniques that were adapted to various droplet microfluidic platforms. We provide a classification of most commonly used droplet platform technologies. Then we discuss the examples of various label-free droplet detection schemes implemented for these platforms. While providing the research landscape for label-free droplet detection methods, we aim to highlight the strengths and shortcomings of each droplet platform so that a more targeted approach can be taken by researchers when selecting a droplet platform and a detection scheme for any given application.
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22
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Pinho B, Liu Y, Rizkin B, Hartman RL. Confined methane-water interfacial layers and thickness measurements using in situ Raman spectroscopy. LAB ON A CHIP 2017; 17:3883-3890. [PMID: 29051944 DOI: 10.1039/c7lc00660h] [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
Gas-liquid interfaces broadly impact our planet, yet confined interfaces behave differently than unconfined ones. We report the role of tangential fluid motion in confined methane-water interfaces. The interfaces are created using microfluidics and investigated by in situ 1D, 2D and 3D Raman spectroscopy. The apparent CH4 and H2O concentrations are reported for Reynolds numbers (Re), ranging from 0.17 to 8.55. Remarkably, the interfaces are comprised of distinct layers of thicknesses varying from 23 to 57 μm. We found that rarefaction, mixture, thin film, and shockwave layers together form the interfaces. The results indicate that the mixture layer thickness (δ) increases with Re (δ ∝ Re), and traditional transport theory for unconfined interfaces does not explain the confined interfaces. A comparison of our results with thin film theory of air-water interfaces (from mass transfer experiments in capillary microfluidics) supports that the hydrophobicity of CH4 could decrease the strength of water-water interactions, resulting in larger interfacial thicknesses. Our findings help explain molecular transport in confined gas-liquid interfaces, which are common in a broad range of societal applications.
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Affiliation(s)
- Bruno Pinho
- Department of Chemical and Biomolecular Engineering, New York University, Brooklyn, NY 11201, USA.
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23
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Maceiczyk RM, Hess D, Chiu FWY, Stavrakis S, deMello AJ. Differential detection photothermal spectroscopy: towards ultra-fast and sensitive label-free detection in picoliter & femtoliter droplets. LAB ON A CHIP 2017; 17:3654-3663. [PMID: 28967022 DOI: 10.1039/c7lc00946a] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/07/2023]
Abstract
Despite the growing importance of droplet-based microfluidics in high-throughput experimentation, few current methods allow the sensitive measurement of absorbance within rapidly moving droplets. To address this significant limitation, we herein present the application of differential detection photothermal interferometry (DDPI) for single-point absorbance quantification in pL- and fL-volume droplets. To assess the efficacy of our approach, we initially measure absorbance in 100 pL droplets at frequencies in excess of 1 kHz and determine a detection limit of 1.4 μmol L-1 for Erythrosin B (A = 3.8 × 10-4). Subsequently, we apply the method to the analysis of fL-volume droplets and droplets generated at frequencies in excess of 10 kHz. Finally, we demonstrate the utility of DDPI as a detection scheme for colorimetric assays. Specifically, we extract the Michaelis-Menten constant for the reaction of β-galactosidase and chlorophenol-red-β-d-galactopyranoside and monitor the metabolomic activity of a population of HL-60 cells at the single cell level. Results establish single-point absorbance detection as a powerful, sensitive and rapid alternative to fluorescence for a wide range of assays within segmented flows.
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Affiliation(s)
- Richard M Maceiczyk
- Institute for Chemical and Bioengineering, Department of Chemistry and Applied Biosciences, ETH Zürich, Vladimir-Prelog-Weg 1, 8093 Zürich, Switzerland.
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24
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Lab-on-Chip, Surface-Enhanced Raman Analysis by Aerosol Jet Printing and Roll-to-Roll Hot Embossing. SENSORS 2017; 17:s17102401. [PMID: 29053610 PMCID: PMC5677385 DOI: 10.3390/s17102401] [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] [Received: 09/29/2017] [Revised: 10/13/2017] [Accepted: 10/18/2017] [Indexed: 02/05/2023]
Abstract
Surface-enhanced Raman spectroscopy (SERS) combines the high specificity of Raman scattering with high sensitivity due to an enhancement of the electromagnetic field by metallic nanostructures. However, the tyical fabrication methods of SERS substrates suffer from low throughput and therefore high costs. Furthermore, point-of-care applications require the investigation of liquid solutions and thus the integration of the SERS substrate in a microfluidic chip. We present a roll-to-roll fabrication approach for microfluidics with integrated, highly efficient, surface-enhanced Raman scattering structures. Microfluidic channels are formed using roll-to-roll hot embossing in polystyrene foil. Aerosol jet printing of a gold nanoparticle ink is utilized to manufacture highly efficient, homogeneous, and reproducible SERS structures. The modified channels are sealed with a solvent-free, roll-to-roll, thermal bonding process. In continuous flow measurements, these chips overcome time-consuming incubation protocols and the poor reproducibility of SERS experiments often caused by inhomogeneous drying of the analyte. In the present study, we explore the influence of the printing process on the homogeneity and the enhancement of the SERS structures. The feasibility of aerosol-jet-modified microfluidic channels for highly sensitive SERS detection is demonstrated by using solutions with different concentrations of Rhodamine 6G and adenosine. The printed areas provide homogeneous enhancement factors of ~4 × 106. Our work shows a way towards the low-cost production of tailor-made, SERS-enabled, label-free, lab-on- chip systems for bioanalysis.
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25
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Dressler OJ, Casadevall I Solvas X, deMello AJ. Chemical and Biological Dynamics Using Droplet-Based Microfluidics. ANNUAL REVIEW OF ANALYTICAL CHEMISTRY (PALO ALTO, CALIF.) 2017; 10:1-24. [PMID: 28375703 DOI: 10.1146/annurev-anchem-061516-045219] [Citation(s) in RCA: 45] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/16/2023]
Abstract
Recent years have witnessed an increased use of droplet-based microfluidic techniques in a wide variety of chemical and biological assays. Nevertheless, obtaining dynamic data from these platforms has remained challenging, as this often requires reading the same droplets (possibly thousands of them) multiple times over a wide range of intervals (from milliseconds to hours). In this review, we introduce the elemental techniques for the formation and manipulation of microfluidic droplets, together with the most recent developments in these areas. We then discuss a wide range of analytical methods that have been successfully adapted for analyte detection in droplets. Finally, we highlight a diversity of studies where droplet-based microfluidic strategies have enabled the characterization of dynamic systems that would otherwise have remained unexplorable.
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Affiliation(s)
- Oliver J Dressler
- Department of Chemistry and Applied Biosciences, ETH Zürich, CH-8093 Zürich, Switzerland;
| | | | - Andrew J deMello
- Department of Chemistry and Applied Biosciences, ETH Zürich, CH-8093 Zürich, Switzerland;
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26
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Beulig RJ, Warias R, Heiland JJ, Ohla S, Zeitler K, Belder D. A droplet-chip/mass spectrometry approach to study organic synthesis at nanoliter scale. LAB ON A CHIP 2017; 17:1996-2002. [PMID: 28513728 DOI: 10.1039/c7lc00313g] [Citation(s) in RCA: 31] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
A droplet-based microfluidic device with seamless hyphenation to electrospray mass spectrometry was developed to rapidly investigate organic reactions in segmented flow providing a versatile tool for drug development. A chip-MS interface with an integrated counterelectrode allowed for a flexible positioning of the chip-emitter in front of the MS orifice as well as an independent adjustment of the electrospray potentials. This was necessary to avoid contamination of the mass spectrometer as well as sample overloading due to the high analyte concentrations. The device was exemplarily applied to study the scope of an amino-catalyzed domino reaction with low picomole amount of catalyst in individual nanoliter sized droplets.
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Affiliation(s)
- R J Beulig
- Institute for Analytical Chemistry, University of Leipzig, Linnéstraße 3, 04103 Leipzig, Germany.
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27
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Tycova A, Prikryl J, Foret F. Recent strategies toward microfluidic-based surface-enhanced Raman spectroscopy. Electrophoresis 2017; 38:1977-1987. [DOI: 10.1002/elps.201700046] [Citation(s) in RCA: 30] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2017] [Revised: 03/20/2017] [Accepted: 04/18/2017] [Indexed: 12/25/2022]
Affiliation(s)
- Anna Tycova
- Institute of Analytical Chemistry of the CAS; v. v. i.; Brno Czech Republic
| | - Jan Prikryl
- Institute of Analytical Chemistry of the CAS; v. v. i.; Brno Czech Republic
| | - Frantisek Foret
- Institute of Analytical Chemistry of the CAS; v. v. i.; Brno Czech Republic
- CEITEC - Central European Institute of Technology; Brno Czech Republic
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28
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Mair P, Gielen F, Hollfelder F. Exploring sequence space in search of functional enzymes using microfluidic droplets. Curr Opin Chem Biol 2017; 37:137-144. [PMID: 28390246 DOI: 10.1016/j.cbpa.2017.02.018] [Citation(s) in RCA: 68] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2017] [Revised: 02/08/2017] [Accepted: 02/15/2017] [Indexed: 12/21/2022]
Abstract
Screening of enzyme mutants in monodisperse picoliter compartments, generated at kilohertz speed in microfluidic devices, is coming of age. After a decade of proof-of-principle experiments, workflows have emerged that combine existing microfluidic modules to assay reaction progress quantitatively and yield improved enzymes. Recent examples of the screening of libraries of randomised proteins and from metagenomic sources suggest that this approach is not only faster and cheaper, but solves problems beyond the feasibility scope of current methodologies. The establishment of new assays in this format - so far covering hydrolases, aldolases, polymerases and dehydrogenases - will enable the exploration of sequence space for new catalysts of natural and non-natural chemical transformations.
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Affiliation(s)
- Philip Mair
- Department of Biochemistry, University of Cambridge, 80 Tennis Court Road, Cambridge CB2 1GA, UK
| | - Fabrice Gielen
- Department of Biochemistry, University of Cambridge, 80 Tennis Court Road, Cambridge CB2 1GA, UK; Living Systems Institute, University of Exeter, Stocker Road, Exeter EX4 4QD, UK
| | - Florian Hollfelder
- Department of Biochemistry, University of Cambridge, 80 Tennis Court Road, Cambridge CB2 1GA, UK.
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29
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Lu H, Zhu L, Zhang C, Wang Z, Lv Y, Chen K, Cui Y. Highly uniform SERS-active microchannel on hydrophobic PDMS: a balance of high reproducibility and sensitivity for detection of proteins. RSC Adv 2017. [DOI: 10.1039/c6ra25173k] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023] Open
Abstract
SERS-active microchannels on hydrophobic polydimethylsiloxane (PDMS) with both high reproducibility and sensitivity are fabricated. Proteins might denature while drying on the SERS-active substrate, but keep native structures in the microchannels.
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Affiliation(s)
- Hui Lu
- Advanced Photonics Center
- Southeast University
- Nanjing 210096
- China
| | - Li Zhu
- Advanced Photonics Center
- Southeast University
- Nanjing 210096
- China
| | - Chuanlong Zhang
- Advanced Photonics Center
- Southeast University
- Nanjing 210096
- China
| | - Zhile Wang
- Advanced Photonics Center
- Southeast University
- Nanjing 210096
- China
| | - Yiru Lv
- Advanced Photonics Center
- Southeast University
- Nanjing 210096
- China
| | - Kexiang Chen
- Advanced Photonics Center
- Southeast University
- Nanjing 210096
- China
| | - Yiping Cui
- Advanced Photonics Center
- Southeast University
- Nanjing 210096
- China
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30
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High-throughput strategies for the discovery and engineering of enzymes for biocatalysis. Bioprocess Biosyst Eng 2016; 40:161-180. [DOI: 10.1007/s00449-016-1690-x] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2016] [Accepted: 10/05/2016] [Indexed: 12/16/2022]
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31
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Braun F, Schwolow S, Seltenreich J, Kockmann N, Röder T, Gretz N, Rädle M. Highly Sensitive Raman Spectroscopy with Low Laser Power for Fast In-Line Reaction and Multiphase Flow Monitoring. Anal Chem 2016; 88:9368-9374. [DOI: 10.1021/acs.analchem.6b01509] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Affiliation(s)
- Frank Braun
- Mannheim University of Applied Sciences, Institute
of Process Control and Innovative Energy Conversion, Paul-Wittsack-Str. 10, 68163 Mannheim, Germany
| | - Sebastian Schwolow
- Mannheim University of Applied Sciences, Institute
of Chemical Process Engineering, Paul-Wittsack-Str. 10, 68163 Mannheim, Germany
| | - Julia Seltenreich
- Mannheim University of Applied Sciences, Institute
of Process Control and Innovative Energy Conversion, Paul-Wittsack-Str. 10, 68163 Mannheim, Germany
| | - Norbert Kockmann
- TU Dortmund University, Biochemical and Chemical
Engineering, Equipment Design, Emil-Figge-Straße 68, 44227 Dortmund, Germany
| | - Thorsten Röder
- Mannheim University of Applied Sciences, Institute
of Chemical Process Engineering, Paul-Wittsack-Str. 10, 68163 Mannheim, Germany
| | - Norbert Gretz
- Medical
Research Center, Medical Faculty Mannheim, University of Heidelberg, Theodor-Kutzer-Ufer 1-3, 68167 Mannheim, Germany
| | - Matthias Rädle
- Mannheim University of Applied Sciences, Institute
of Process Control and Innovative Energy Conversion, Paul-Wittsack-Str. 10, 68163 Mannheim, Germany
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32
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Liao W, Lu X. Determination of chemical hazards in foods using surface-enhanced Raman spectroscopy coupled with advanced separation techniques. Trends Food Sci Technol 2016. [DOI: 10.1016/j.tifs.2016.05.020] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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33
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Abalde-Cela S, Carregal-Romero S, Coelho JP, Guerrero-Martínez A. Recent progress on colloidal metal nanoparticles as signal enhancers in nanosensing. Adv Colloid Interface Sci 2016; 233:255-270. [PMID: 26094082 DOI: 10.1016/j.cis.2015.05.002] [Citation(s) in RCA: 50] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2015] [Revised: 05/08/2015] [Accepted: 05/12/2015] [Indexed: 11/30/2022]
Abstract
Colloidal metal nanoparticles present very special optical and electromagnetic properties at the nanoscale range. Such plasmonic properties have derived in a huge research field that encompasses the understanding of nanoparticle formation mechanisms for the ultimate goal of developing novel materials for real-life applications. Plasmonic sensing is experiencing a rapid transition by taking advantage of the characteristic properties of colloidal metal nanoparticles. However, a rational design of novel nanoplasmonic substrates, which gathers as much as the required properties for a substrate to be a 'good' sensor is critical through the development of applications that can be effectively transferred as applied technologies. Also, the chosen sensing technique is a key factor when planning the design of a new plasmonic-based sensor. Several factors such as composition, shape, size, particle interactions or stability among others will define the final quality of the nanomaterial as sensing platform. Herein, we review the latest and most promising state-of-the art of nanoplasmonic-based sensors in four differentiated areas regarding the surface-enhanced spectroscopy detection technique being LSPR-, SERS- and SEIRA-, and SEF based platforms.
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Affiliation(s)
- Sara Abalde-Cela
- Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge CB2 1EW, UK
| | - Susana Carregal-Romero
- Bionanoplasmonics Laboratory, CIC biomaGUNE, Paseo de Miramón 182, 20009 Donostia-San Sebastián, Spain; Oncology Area, Biodonostia Research Institute, Donostia-San Sebastián 20014, Spain
| | - João Paulo Coelho
- Departamento de Química Física I, Universidad Complutense de Madrid, Avda. Complutense s/n, 28040 Madrid, Spain
| | - Andrés Guerrero-Martínez
- Departamento de Química Física I, Universidad Complutense de Madrid, Avda. Complutense s/n, 28040 Madrid, Spain.
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34
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Sans V, Cronin L. Towards dial-a-molecule by integrating continuous flow, analytics and self-optimisation. Chem Soc Rev 2016; 45:2032-43. [PMID: 26815081 PMCID: PMC6057606 DOI: 10.1039/c5cs00793c] [Citation(s) in RCA: 125] [Impact Index Per Article: 15.6] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
The employment of continuous-flow platforms for synthetic chemistry is becoming increasingly popular in research and industrial environments. Integrating analytics in-line enables obtaining a large amount of information in real-time about the reaction progress, catalytic activity and stability, etc. Furthermore, it is possible to influence the reaction progress and selectivity via manual or automated feedback optimisation, thus constituting a dial-a-molecule approach employing digital synthesis. This contribution gives an overview of the most significant contributions in the field to date.
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Affiliation(s)
- Victor Sans
- Department of Chemical and Environmental Engineering, University of Nottingham, NG7 2RD, UK.
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35
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Shembekar N, Chaipan C, Utharala R, Merten CA. Droplet-based microfluidics in drug discovery, transcriptomics and high-throughput molecular genetics. LAB ON A CHIP 2016; 16:1314-31. [PMID: 27025767 DOI: 10.1039/c6lc00249h] [Citation(s) in RCA: 210] [Impact Index Per Article: 26.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/04/2023]
Abstract
Droplet-based microfluidics enables assays to be carried out at very high throughput (up to thousands of samples per second) and enables researchers to work with very limited material, such as primary cells, patient's biopsies or expensive reagents. An additional strength of the technology is the possibility to perform large-scale genotypic or phenotypic screens at the single-cell level. Here we critically review the latest developments in antibody screening, drug discovery and highly multiplexed genomic applications such as targeted genetic workflows, single-cell RNAseq and single-cell ChIPseq. Starting with a comprehensive introduction for non-experts, we pinpoint current limitations, analyze how they might be overcome and give an outlook on exciting future applications.
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Affiliation(s)
- Nachiket Shembekar
- European Molecular Biology Laboratory (EMBL), Genome Biology Unit, Meyerhofstrasse 1, Heidelberg, Germany.
| | - Chawaree Chaipan
- European Molecular Biology Laboratory (EMBL), Genome Biology Unit, Meyerhofstrasse 1, Heidelberg, Germany.
| | - Ramesh Utharala
- European Molecular Biology Laboratory (EMBL), Genome Biology Unit, Meyerhofstrasse 1, Heidelberg, Germany.
| | - Christoph A Merten
- European Molecular Biology Laboratory (EMBL), Genome Biology Unit, Meyerhofstrasse 1, Heidelberg, Germany.
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Boken J, Soni SK, Kumar D. Microfluidic Synthesis of Nanoparticles and their Biosensing Applications. Crit Rev Anal Chem 2016; 46:538-61. [DOI: 10.1080/10408347.2016.1169912] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
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Rattanarat P, Suea-Ngam A, Ruecha N, Siangproh W, Henry CS, Srisa-Art M, Chailapakul O. Graphene-polyaniline modified electrochemical droplet-based microfluidic sensor for high-throughput determination of 4-aminophenol. Anal Chim Acta 2016; 925:51-60. [PMID: 27188317 DOI: 10.1016/j.aca.2016.03.010] [Citation(s) in RCA: 50] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2015] [Revised: 12/29/2015] [Accepted: 03/07/2016] [Indexed: 01/12/2023]
Abstract
We report herein the first development of graphene-polyaniline modified carbon paste electrode (G-PANI/CPE) coupled with droplet-based microfluidic sensor for high-throughput detection of 4-aminophenol (4-AP) in pharmaceutical paracetamol (PA) formulations. A simple T-junction microfluidic platform using an oil flow rate of 1.8 μL/min and an aqueous flow rate of 0.8 μL/min was used to produce aqueous testing microdroplets continuously. The microchannel was designed to extend the aqueous droplet to cover all 3 electrodes, allowing for electrochemical measurements in a single droplet. Parameters including flow rate, water fraction, and applied detection potential (Edet) were investigated to obtain optimal conditions. Using G-PANI/CPE significantly increased the current response for both cyclic voltammetric detections of ferri/ferrocyanide [Fe(CN)6](3-/4-) (10 times) and 4-AP (2 times), compared to an unmodified electrode. Using the optimized conditions in the droplet system, 4-AP in the presence of PA was selectively determined. The linear range of 4-AP was 50-500 μM (R(2) = 0.99), limit of detection (LOD, S/N = 3) was 15.68 μM, and limit of quantification (LOQ, S/N = 10) was 52.28 μM. Finally, the system was used to determine 4-AP spiked in commercial PA liquid samples and the amounts of 4-AP were found in good agreement with those obtained from the conventional capillary zone electrophoresis/UV-Visible spectrophotometry (CZE/UV-Vis). The proposed microfluidic device could be employed for a high-throughput screening (at least 60 samples h(-1)) of pharmaceutical purity requiring low sample and reagent consumption.
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Affiliation(s)
- Poomrat Rattanarat
- Electrochemistry and Optical Spectroscopy Research Unit (EOSRU), Department of Chemistry, Faculty of Science, Chulalongkorn University, Patumwan, Bangkok 10330, Thailand
| | - Akkapol Suea-Ngam
- Electrochemistry and Optical Spectroscopy Research Unit (EOSRU), Department of Chemistry, Faculty of Science, Chulalongkorn University, Patumwan, Bangkok 10330, Thailand; Chromatography and Separation Research Unit (ChSRU), Department of Chemistry, Faculty of Science, Chulalongkorn University, Patumwan, Bangkok 10330, Thailand
| | - Nipapan Ruecha
- Program in Macromolecular Science, Faculty of Science, Chulalongkorn University, Patumwan, Bangkok 10330, Thailand
| | - Weena Siangproh
- Department of Chemistry, Faculty of Science, Srinakharinwirot University, Sukhumvit 23, Wattana, Bangkok 10110, Thailand
| | - Charles S Henry
- Department of Chemistry, Colorado State University, Fort Collins, CO 80523, United States; School of Biomedical Engineering, Colorado State University, Fort Collins, CO 80523, United States
| | - Monpichar Srisa-Art
- Electrochemistry and Optical Spectroscopy Research Unit (EOSRU), Department of Chemistry, Faculty of Science, Chulalongkorn University, Patumwan, Bangkok 10330, Thailand; Chromatography and Separation Research Unit (ChSRU), Department of Chemistry, Faculty of Science, Chulalongkorn University, Patumwan, Bangkok 10330, Thailand
| | - Orawon Chailapakul
- Electrochemistry and Optical Spectroscopy Research Unit (EOSRU), Department of Chemistry, Faculty of Science, Chulalongkorn University, Patumwan, Bangkok 10330, Thailand; National Center of Excellent of Petroleum, Petrochemicals and Advanced Materials, Chulalongkorn University, Patumwan, Bangkok 10330, Thailand.
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Salmon AR, Esteban R, Taylor RW, Hugall JT, Smith CA, Whyte G, Scherman OA, Aizpurua J, Abell C, Baumberg JJ. Monitoring Early-Stage Nanoparticle Assembly in Microdroplets by Optical Spectroscopy and SERS. SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2016; 12:1788-96. [PMID: 26865562 DOI: 10.1002/smll.201503513] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/18/2015] [Revised: 01/11/2016] [Indexed: 05/19/2023]
Abstract
Microfluidic microdroplets have increasingly found application in biomolecular sensing as well as nanomaterials growth. More recently the synthesis of plasmonic nanostructures in microdroplets has led to surface-enhanced Raman spectroscopy (SERS)-based sensing applications. However, the study of nanoassembly in microdroplets has previously been hindered by the lack of on-chip characterization tools, particularly at early timescales. Enabled by a refractive index matching microdroplet formulation, dark-field spectroscopy is exploited to directly track the formation of nanometer-spaced gold nanoparticle assemblies in microdroplets. Measurements in flow provide millisecond time resolution through the assembly process, allowing identification of a regime where dimer formation dominates the dark-field scattering and SERS. Furthermore, it is shown that small numbers of nanoparticles can be isolated in microdroplets, paving the way for simple high-yield assembly, isolation, and sorting of few nanoparticle structures.
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Affiliation(s)
- Andrew R Salmon
- Department of Chemistry, University of Cambridge, Lensfield Rd, Cambridge, CB2 1EW, UK
- Department of Physics, University of Cambridge, Cavendish Laboratory, JJ Thompson Avenue, Cambridge, CB3 0HE, UK
| | - Ruben Esteban
- Materials Physics Center (CSIC-UPV/EHU) and DIPC, Paseo Manuel de Lardizabal 4, Donostia-San Sebastian, ES, 20018, Spain
| | - Richard W Taylor
- Department of Physics, University of Cambridge, Cavendish Laboratory, JJ Thompson Avenue, Cambridge, CB3 0HE, UK
| | - James T Hugall
- Department of Physics, University of Cambridge, Cavendish Laboratory, JJ Thompson Avenue, Cambridge, CB3 0HE, UK
- ICFO, The Barcelona Institute of Science and Technology, Barcelona, 08860, Spain
| | - Clive A Smith
- Sphere Fluidics Limited, Babraham Research Campus, Cambridge, CB22 3AT, UK
| | - Graeme Whyte
- Heriot-Watt University, School of Engineering and Physical Sciences, David Brewster Building, Edinburgh, EH14 4AS, UK
| | - Oren A Scherman
- Department of Chemistry, University of Cambridge, Lensfield Rd, Cambridge, CB2 1EW, UK
| | - Javier Aizpurua
- Materials Physics Center (CSIC-UPV/EHU) and DIPC, Paseo Manuel de Lardizabal 4, Donostia-San Sebastian, ES, 20018, Spain
| | - Chris Abell
- Department of Chemistry, University of Cambridge, Lensfield Rd, Cambridge, CB2 1EW, UK
| | - Jeremy J Baumberg
- Department of Physics, University of Cambridge, Cavendish Laboratory, JJ Thompson Avenue, Cambridge, CB3 0HE, UK
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High-Throughput Screening in Protein Engineering: Recent Advances and Future Perspectives. Int J Mol Sci 2015; 16:24918-45. [PMID: 26492240 PMCID: PMC4632782 DOI: 10.3390/ijms161024918] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2015] [Revised: 10/13/2015] [Accepted: 10/13/2015] [Indexed: 11/17/2022] Open
Abstract
Over the last three decades, protein engineering has established itself as an important tool for the development of enzymes and (therapeutic) proteins with improved characteristics. New mutagenesis techniques and computational design tools have greatly aided in the advancement of protein engineering. Yet, one of the pivotal components to further advance protein engineering strategies is the high-throughput screening of variants. Compartmentalization is one of the key features allowing miniaturization and acceleration of screening. This review focuses on novel screening technologies applied in protein engineering, highlighting flow cytometry- and microfluidics-based platforms.
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Abstract
Improved surface-enhanced Raman scattering (SERS) measurements of a flowing aqueous sample are accomplished by combining line focus optics with sheath-flow SERS detection. The straightforward introduction of a cylindrical lens into the optical path of the Raman excitation laser increases the efficiency of SERS detection and the reproducibility of SERS signals at low concentrations. The width of the line focus is matched to the width of the sample capillary from which the analyte elutes under hydrodynamic focusing conditions, allowing for increased collection across the SERS substrate while maintaining the power density below the damage threshold at any specific point. We show that a 4× increase in power spread across the line increases the signal-to-noise ratio by a factor of 2 for a variety of analytes, such as rhodamine 6G, amino acids, and lipid vesicles, without any detectable photodamage. COMSOL simulations and Raman maps elucidate the hydrodynamic focusing properties of the flow cell, providing a clearer picture of the confinement effects at the surface where the sample exits the capillary. The lipid vesicle results suggest that the combination of hydrodynamic focusing and increased optical collection enables the reproducible detection of rare events, in this case individual lipid vesicles.
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Affiliation(s)
- Kevin T. Jacobs
- University of Notre Dame, Department of Chemistry and Biochemistry, Notre Dame, IN, 46556, USA
| | - Zachary D. Schultz
- University of Notre Dame, Department of Chemistry and Biochemistry, Notre Dame, IN, 46556, USA
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Fukuyama M, Hibara A. Microfluidic Selective Concentration of Microdroplet Contents by Spontaneous Emulsification. Anal Chem 2015; 87:3562-5. [DOI: 10.1021/acs.analchem.5b00155] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Affiliation(s)
- Mao Fukuyama
- Department
of Chemistry, Tokyo Institute of Technology, 2-12-1-W4-20 Ookayama Meguro-ku
Tokyo, 152-8551, Japan
| | - Akihide Hibara
- Department
of Chemistry, Tokyo Institute of Technology, 2-12-1-W4-20 Ookayama Meguro-ku
Tokyo, 152-8551, Japan
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Abstract
Droplet microfluidics may soon change the paradigm of performing chemical analyses and related instrumentation.
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Affiliation(s)
- Evgenia Yu Basova
- Masaryk University
- CEITEC, Central European Institute Technology
- Brno
- Czech Republic
| | - Frantisek Foret
- Masaryk University
- CEITEC, Central European Institute Technology
- Brno
- Czech Republic
- Institute of Analytical Chemistry of the Academy of Sciences of the Czech Republic
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43
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Au nanoparticles enhanced fluorescence detection of DNA hybridization in picoliter microfluidic droplets. Biomed Microdevices 2014; 16:479-85. [PMID: 24599582 DOI: 10.1007/s10544-014-9850-8] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Abstract
This work reports a facile microfluidic device for Au-nanoparticle enhanced fluorescence detection of tiny amount of nucleotides within droplets in a high-throughput way. Droplets containing single strand DNA probe and relevant complementary strands DNA(cDNA) are generated in flow-focusing manner and the hybridization between them is realized in droplets flowing along a long serpentine channel. In order to find the optimal experimental condition, finite element method simulation is used to predict the interface evolution between the two phase liquids. Based on the fluorescence emited by intercalator reacted with the generated double-strand DNA(dsDNA), the target cDNA with a concentration of 1nM can be detected in droplets. And when we adopt Au nanoparticles to immobilize DNA probe which can amplify the fluorescence intensity, 10pM completary DNA could be detected. Due to the advantages in high-throughput and compartmentalization of this droplet platform, the detection procedure can be finished in 3 h. Our method shows good potential application in facile, sensitive, low cost and fast DNA detection for applications in personal health care.
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Betz JF, Yu WW, Cheng Y, White IM, Rubloff GW. Simple SERS substrates: powerful, portable, and full of potential. Phys Chem Chem Phys 2014; 16:2224-39. [PMID: 24366393 DOI: 10.1039/c3cp53560f] [Citation(s) in RCA: 117] [Impact Index Per Article: 11.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Surface enhanced Raman spectroscopy (SERS) is a powerful spectroscopic technique capable of detecting trace amounts of chemicals and identifying them based on their unique vibrational characteristics. While there are many complex methods for fabricating SERS substrates, there has been a recent shift towards the development of simple, low cost fabrication methods that can be performed in most labs or even in the field. The potential of SERS for widespread use will likely be realized only with development of cheaper, simpler methods. In this Perspective article we briefly review several of the more popular methods for SERS substrate fabrication, discuss the characteristics of simple SERS substrates, and examine several methods for producing simple SERS substrates. We highlight potential applications and future directions for simple SERS substrates, focusing on highly SERS active three-dimensional nanostructures fabricated by inkjet and screen printing and galvanic displacement for portable SERS analysis - an area that we believe has exciting potential for future research and commercialization.
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Affiliation(s)
- Jordan F Betz
- Fischell Department of Bioengineering, University of Maryland, College Park, MD, USA
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Luther SK, Will S, Braeuer A. Phase-specific Raman spectroscopy for fast segmented microfluidic flows. LAB ON A CHIP 2014; 14:2910-2913. [PMID: 24920388 DOI: 10.1039/c4lc00428k] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
An intensifier based Raman measuring strategy is introduced which allows for a phase-specific signal detection of one single phase in segmented flows at droplet generation frequencies of potentially up to several kHz.
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Affiliation(s)
- S K Luther
- Lehrstuhl für Technische Thermodynamik (LTT) and Erlangen Graduate School in Advanced Optical Technologies (SAOT), Friedrich-Alexander Universität Erlangen-Nürnberg (FAU), Erlangen, Germany.
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46
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Gao R, Choi N, Chang SI, Lee EK, Choo J. Real-time analysis of diaquat dibromide monohydrate in water with a SERS-based integrated microdroplet sensor. NANOSCALE 2014; 6:8781-6. [PMID: 24954446 DOI: 10.1039/c4nr01269k] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/18/2023]
Abstract
We report the fast and sensitive trace analysis of diaquat dibromide monohydrate (DQ) in water using a surface-enhanced Raman scattering (SERS)-based microdroplet sensor. This sensor is composed of two compartments: the first one is for droplet generation for fresh silver nanoparticle (AgNP) synthesis and the second for droplet merging for SERS detection. Silver ions were nucleated and grown to large size AgNPs in droplets, and then each droplet was synchronously merged with another droplet containing DQ for SERS detection. This two-phase liquid-liquid segmented flow system prevented memory effects caused by the precipitation of nanoparticle aggregates on channel walls because the aqueous droplets were isolated by a continuous oil phase. The limit of detection (LOD) of DQ in water was determined to be below 5 nM, which satisfies the maximum contaminant level defined by the United States EPA. This method was also validated successfully in DQ-spiked tap water. The SERS-based integrated sensing system is expected to be useful as an in-the-field sensing platform for fast and reproducible trace analysis of environmental pollutants in water.
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Affiliation(s)
- Rongke Gao
- Department of Bionano Technology, Hanyang University, Ansan 426-791, South Korea.
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Gibb TR, Ivanov AP, Edel JB, Albrecht T. Single Molecule Ionic Current Sensing in Segmented Flow Microfluidics. Anal Chem 2014; 86:1864-71. [DOI: 10.1021/ac403921m] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Affiliation(s)
- Thomas R. Gibb
- Department of Chemistry, Imperial College London, South Kensington Campus, London, SW7
2AZ, United Kingdom
| | - Aleksandar P. Ivanov
- Department of Chemistry, Imperial College London, South Kensington Campus, London, SW7
2AZ, United Kingdom
| | - Joshua B. Edel
- Department of Chemistry, Imperial College London, South Kensington Campus, London, SW7
2AZ, United Kingdom
| | - Tim Albrecht
- Department of Chemistry, Imperial College London, South Kensington Campus, London, SW7
2AZ, United Kingdom
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48
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Zhang Y, Li H, Ma Y, Lin JM. Paper spray mass spectrometry-based method for analysis of droplets in a gravity-driven microfluidic chip. Analyst 2014; 139:1023-9. [PMID: 24432351 DOI: 10.1039/c3an01769a] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
This work presents a paper spray mass spectrometry-based method, to analyze microdroplets produced in a gravity-driven microchip. Droplets at ambient pressure were passively transferred from the chip to a paper substrate by the capillary wicking effect. Paper spray ionization was then performed for mass spectrometry (MS) analysis of droplet contents. The qualitative and quantitative analytical performances of this technique for single droplets were demonstrated. This manually controlled interface is straightforward, low-cost and simple to implement. Moreover, paper spray ionization MS holds promise in the direct analysis of real biological/chemical microreaction samples because of its tolerance with complex matrices. As a proof-of-concept example, the droplet-based acetylcholine hydrolysis was carried out to demonstrate the validation of our method for the direct analysis of micro-chemical/biological reactions. We also introduced a flow injection analysis (FIA) system combined with our droplet system to generate a concentration gradient. As a result, the microreaction can be performed at different concentrations and kinetic information can be obtained in one sample injection. In conclusion, the combination of a microdroplet chip with paper spray ionization and the introduction of the FIA system and make our droplet-MS scheme a useful platform for monitoring and analyzing organic-phase chemical/biological reactions.
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Affiliation(s)
- Yandong Zhang
- Beijing Key Laboratory Microanalytical Methods and Instrumentation, Department of Chemistry, Tsinghua University, Beijing 100084, China.
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49
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Chen G, Wang Y, Wang H, Cong M, Chen L, Yang Y, Geng Y, Li H, Xu S, Xu W. A highly sensitive microfluidics system for multiplexed surface-enhanced Raman scattering (SERS) detection based on Ag nanodot arrays. RSC Adv 2014. [DOI: 10.1039/c4ra09251a] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
We present a microfluidics system with Ag nanodot arrays as the enhancement substrate for multiplexed SERS detection of low-concentration mixtures of thiram and adenine.
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Affiliation(s)
- Gang Chen
- State Key Laboratory of Supramolecular Structure and Materials
- Institute of Theoretical Chemistry
- Jilin University
- Changchun, People's Republic of China
- College of Chemistry
| | - Yuyang Wang
- State Key Laboratory of Supramolecular Structure and Materials
- Institute of Theoretical Chemistry
- Jilin University
- Changchun, People's Republic of China
| | - Hailong Wang
- State Key Laboratory of Supramolecular Structure and Materials
- Institute of Theoretical Chemistry
- Jilin University
- Changchun, People's Republic of China
| | - Ming Cong
- State Key Laboratory of Supramolecular Structure and Materials
- Institute of Theoretical Chemistry
- Jilin University
- Changchun, People's Republic of China
| | - Lei Chen
- State Key Laboratory of Supramolecular Structure and Materials
- Institute of Theoretical Chemistry
- Jilin University
- Changchun, People's Republic of China
- College of Physics
| | - Yongan Yang
- Department of Physics and Electronic Science
- Chu Xiong Normal University
- Chuxiong 675000, People's Republic of China
| | - Yijia Geng
- State Key Laboratory of Supramolecular Structure and Materials
- Institute of Theoretical Chemistry
- Jilin University
- Changchun, People's Republic of China
- College of Physics
| | - Haibo Li
- State Key Laboratory of Supramolecular Structure and Materials
- Institute of Theoretical Chemistry
- Jilin University
- Changchun, People's Republic of China
| | - Shuping Xu
- State Key Laboratory of Supramolecular Structure and Materials
- Institute of Theoretical Chemistry
- Jilin University
- Changchun, People's Republic of China
| | - Weiqing Xu
- State Key Laboratory of Supramolecular Structure and Materials
- Institute of Theoretical Chemistry
- Jilin University
- Changchun, People's Republic of China
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50
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Turek VA, Elliott LN, Tyler AII, Demetriadou A, Paget J, Cecchini MP, Kucernak AR, Kornyshev AA, Edel JB. Self-assembly and applications of ultraconcentrated nanoparticle solutions. ACS NANO 2013; 7:8753-8759. [PMID: 24070428 DOI: 10.1021/nn403131e] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
We demonstrate a highly efficient method for concentrating, purifying and separating gold nanoparticles. The method relies on localized density gradients that can be formed at an aqueous | organic phase interface. We show that this method is able to concentrate aqueous gold nanoparticles to the point where confinement leads to variable interparticle separations. Furthermore, the physical properties of the resulting solution are drastically altered when compared to water. For example, densities higher than 4.5 g/cm(3) could be generated without nanoparticle aggregation. As far as we are aware, this is one of the highest reported densities of an aqueous solution at room temperature. Finally, the compositions of the solutions generated are highly dependent on parameters such as particle size and background analyte making this technique highly advantageous for the separation of multimodal NP populations and chemical purification, with 99.5% and >99.9% efficiency, respectively.
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Affiliation(s)
- Vladimir A Turek
- Department of Chemistry, Imperial College London , South Kensington Campus, London, SW7 2AZ United Kingdon
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