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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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Gantz M, Neun S, Medcalf EJ, van Vliet LD, Hollfelder F. Ultrahigh-Throughput Enzyme Engineering and Discovery in In Vitro Compartments. Chem Rev 2023; 123:5571-5611. [PMID: 37126602 PMCID: PMC10176489 DOI: 10.1021/acs.chemrev.2c00910] [Citation(s) in RCA: 12] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/03/2023]
Abstract
Novel and improved biocatalysts are increasingly sourced from libraries via experimental screening. The success of such campaigns is crucially dependent on the number of candidates tested. Water-in-oil emulsion droplets can replace the classical test tube, to provide in vitro compartments as an alternative screening format, containing genotype and phenotype and enabling a readout of function. The scale-down to micrometer droplet diameters and picoliter volumes brings about a >107-fold volume reduction compared to 96-well-plate screening. Droplets made in automated microfluidic devices can be integrated into modular workflows to set up multistep screening protocols involving various detection modes to sort >107 variants a day with kHz frequencies. The repertoire of assays available for droplet screening covers all seven enzyme commission (EC) number classes, setting the stage for widespread use of droplet microfluidics in everyday biochemical experiments. We review the practicalities of adapting droplet screening for enzyme discovery and for detailed kinetic characterization. These new ways of working will not just accelerate discovery experiments currently limited by screening capacity but profoundly change the paradigms we can probe. By interfacing the results of ultrahigh-throughput droplet screening with next-generation sequencing and deep learning, strategies for directed evolution can be implemented, examined, and evaluated.
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Affiliation(s)
- Maximilian Gantz
- Department of Biochemistry, University of Cambridge, 80 Tennis Court Rd, Cambridge CB2 1GA, U.K
| | - Stefanie Neun
- Department of Biochemistry, University of Cambridge, 80 Tennis Court Rd, Cambridge CB2 1GA, U.K
| | - Elliot J Medcalf
- Department of Biochemistry, University of Cambridge, 80 Tennis Court Rd, Cambridge CB2 1GA, U.K
| | - Liisa D van Vliet
- Department of Biochemistry, University of Cambridge, 80 Tennis Court Rd, Cambridge CB2 1GA, U.K
| | - Florian Hollfelder
- Department of Biochemistry, University of Cambridge, 80 Tennis Court Rd, Cambridge CB2 1GA, U.K
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Sun G, Qu L, Azi F, Liu Y, Li J, Lv X, Du G, Chen J, Chen CH, Liu L. Recent progress in high-throughput droplet screening and sorting for bioanalysis. Biosens Bioelectron 2023; 225:115107. [PMID: 36731396 DOI: 10.1016/j.bios.2023.115107] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2022] [Revised: 01/09/2023] [Accepted: 01/25/2023] [Indexed: 01/31/2023]
Abstract
Owing to its ability to isolate single cells and perform high-throughput sorting, droplet sorting has been widely applied in several research fields. Compared with flow cytometry, droplet allows the encapsulation of single cells for cell secretion or lysate analysis. With the rapid development of this technology in the past decade, various droplet sorting devices with high throughput and accuracy have been developed. A droplet sorter with the highest sorting throughput of 30,000 droplets per second was developed in 2015. Since then, increased attention has been paid to expanding the possibilities of droplet sorting technology and strengthening its advantages over flow cytometry. This review aimed to summarize the recent progress in droplet sorting technology from the perspectives of device design, detection signal, actuating force, and applications. Technical details for improving droplet sorting through various approaches are introduced and discussed. Finally, we discuss the current limitations of droplet sorting for single-cell studies along with the existing gap between the laboratory and industry and provide our insights for future development of droplet sorters.
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Affiliation(s)
- Guoyun Sun
- Science Center for Future Foods, Jiangnan University, Wuxi, 214122, China; Key Laboratory of Carbohydrate Chemistry and Biotechnology, Ministry of Education, Jiangnan University, Wuxi, 214122, China
| | - Lisha Qu
- Key Laboratory of Carbohydrate Chemistry and Biotechnology, Ministry of Education, Jiangnan University, Wuxi, 214122, China
| | - Fidelis Azi
- Department of Chemical Engineering, Guangdong Technion-Israel Institute of Technology GTIIT, Shantou, Guangdong, 515063, China
| | - Yanfeng Liu
- Science Center for Future Foods, Jiangnan University, Wuxi, 214122, China; Key Laboratory of Carbohydrate Chemistry and Biotechnology, Ministry of Education, Jiangnan University, Wuxi, 214122, China
| | - Jianghua Li
- Key Laboratory of Carbohydrate Chemistry and Biotechnology, Ministry of Education, Jiangnan University, Wuxi, 214122, China
| | - Xueqin Lv
- Science Center for Future Foods, Jiangnan University, Wuxi, 214122, China; Key Laboratory of Carbohydrate Chemistry and Biotechnology, Ministry of Education, Jiangnan University, Wuxi, 214122, China
| | - Guocheng Du
- Science Center for Future Foods, Jiangnan University, Wuxi, 214122, China; Key Laboratory of Carbohydrate Chemistry and Biotechnology, Ministry of Education, Jiangnan University, Wuxi, 214122, China
| | - Jian Chen
- Science Center for Future Foods, Jiangnan University, Wuxi, 214122, China; Key Laboratory of Carbohydrate Chemistry and Biotechnology, Ministry of Education, Jiangnan University, Wuxi, 214122, China
| | - Chia-Hung Chen
- Department of Biomedical Engineering, College of Engineering, City University of Hong Kong, Hong Kong, China.
| | - Long Liu
- Science Center for Future Foods, Jiangnan University, Wuxi, 214122, China; Key Laboratory of Carbohydrate Chemistry and Biotechnology, Ministry of Education, Jiangnan University, Wuxi, 214122, China.
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Das A, Fehse S, Polack M, Panneerselvam R, Belder D. Surface-Enhanced Raman Spectroscopic Probing in Digital Microfluidics through a Microspray Hole. Anal Chem 2023; 95:1262-1272. [PMID: 36577121 DOI: 10.1021/acs.analchem.2c04053] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
We report a novel approach for surface-enhanced Raman spectroscopy (SERS) detection in digital microfluidics (DMF). This is made possible by a microspray hole (μSH) that uses an electrostatic spray (ESTAS) for sample transfer from inside the chip to an external SERS substrate. To realize this, a new ESTAS-compatible stationary SERS substrate was developed and characterized for sensitive and reproducible SERS measurements. In a proof-of-concept study, we successfully applied the approach to detect various analyte molecules using the DMF chip and achieved micro-molar detection limits. Moreover, this technique was exemplarily employed to study an organic reaction occurring in the DMF device, providing vibrational spectroscopic data.
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Affiliation(s)
- Anish Das
- Institute of Analytical Chemistry, Leipzig University, Linnéstraße 3, Leipzig 04103, Germany
| | - Sebastian Fehse
- Institute of Analytical Chemistry, Leipzig University, Linnéstraße 3, Leipzig 04103, Germany
| | - Matthias Polack
- Institute of Analytical Chemistry, Leipzig University, Linnéstraße 3, Leipzig 04103, Germany
| | - Rajapandiyan Panneerselvam
- Institute of Analytical Chemistry, Leipzig University, Linnéstraße 3, Leipzig 04103, Germany.,Department of Chemistry, SRM University AP, Amaravati, Andhra Pradesh 522502, India
| | - Detlev Belder
- Institute of Analytical Chemistry, Leipzig University, Linnéstraße 3, Leipzig 04103, Germany
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Zhou J, Wei A, Bertsch A, Renaud P. High precision, high throughput generation of droplets containing single cells. LAB ON A CHIP 2022; 22:4841-4848. [PMID: 36416090 DOI: 10.1039/d2lc00841f] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/16/2023]
Abstract
The Poisson limit is a major problem for the isolation of single cells in different single-cell technologies and applications. In droplet-based single-cell assays, a scheme that is increasingly popular, the intrinsic randomness during single-cell encapsulation in droplets requires most of the created droplets to be empty, which has a profound impact on the efficiency and throughput of such techniques, and on the predictability of the combinatory droplet assays. Here we present a simple passive microfluidic system overcoming this limitation with unprecedented efficacy, allowing the generation of single-cell droplets for a wide range of operating conditions, with extremely high throughput (more than 22 000 single-cell loaded droplets per minute) and with an extremely low fault ratio (doublets or empty droplets), applicable to any cells and deformable particles. This versatile technique will shift the paradigm of single-cell encapsulation and will impact single-cell sequencing, rare cell isolation, multicellular/bead studies in immunology or cancer biology, etc.
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Affiliation(s)
- Jiande Zhou
- Laboratory of Microsystems 4, Swiss Federal Institute of Technology Lausanne (EPFL), Lausanne, Switzerland.
| | - Amaury Wei
- Laboratory of Microsystems 4, Swiss Federal Institute of Technology Lausanne (EPFL), Lausanne, Switzerland.
| | - Arnaud Bertsch
- Laboratory of Microsystems 4, Swiss Federal Institute of Technology Lausanne (EPFL), Lausanne, Switzerland.
| | - Philippe Renaud
- Laboratory of Microsystems 4, Swiss Federal Institute of Technology Lausanne (EPFL), Lausanne, Switzerland.
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Recent advances of integrated microfluidic systems for fungal and bacterial analysis. Trends Analyt Chem 2022. [DOI: 10.1016/j.trac.2022.116850] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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Blaha ME, Hasan S, Dusny C, Belder D. Fluorescence lifetime activated droplet sorting (FLADS) for label-free sorting of Synechocystis sp. PCC6803. LAB ON A CHIP 2022; 22:1604-1614. [PMID: 35332894 DOI: 10.1039/d2lc00032f] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
This study presents the label-free sorting of cyanobacterial cells in droplets with single-cell sensitivity based on their fluorescence lifetime. We separated living and dead cyanobacteria (Synechocystis sp. PCC6803) using fluorescence lifetime signals of the photopigment autofluorescence to indicate their photosynthetic activity. We developed a setup and a chip design to achieve live/dead sorting accuracies of more than 97% at a droplet frequency of 100 Hz with a PDMS-based chip system and standard optics using fluorescence lifetime as the sorting criterion. The obtained sorting accuracies could be experimentally confirmed by cell plating and observing the droplet sorting process via a high-speed camera. The herein presented results demonstrate the capabilities of the developed system for studying the effects of stressors on cyanobacterial physiology and the subsequent deterministic sorting of different stress-response phenotypes. This technology eliminates the need for tedious staining of cyanobacterial cells, which makes it particularly attractive for its application in the field of phototrophic microbial bio(techno)logic and in the context of cell secretion studies.
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Affiliation(s)
| | - Sadat Hasan
- Institute for Analytical Chemistry, Leipzig University, Linnéstraße 3, 04103 Leipzig, Germany.
| | - Christian Dusny
- Department Solar Materials, Helmoltz-Centre for Environmental Research - UFZ Leipzig, Permoserstr. 15, 04318 Leipzig, Germany
| | - Detlev Belder
- Institute for Analytical Chemistry, Leipzig University, Linnéstraße 3, 04103 Leipzig, Germany.
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