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Vladisaljević GT. Droplet Microfluidics for High-Throughput Screening and Directed Evolution of Biomolecules. MICROMACHINES 2024; 15:971. [PMID: 39203623 PMCID: PMC11356158 DOI: 10.3390/mi15080971] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 06/24/2024] [Revised: 07/23/2024] [Accepted: 07/26/2024] [Indexed: 09/03/2024]
Abstract
Directed evolution is a powerful technique for creating biomolecules such as proteins and nucleic acids with tailor-made properties for therapeutic and industrial applications by mimicking the natural evolution processes in the laboratory. Droplet microfluidics improved classical directed evolution by enabling time-consuming and laborious steps in this iterative process to be performed within monodispersed droplets in a highly controlled and automated manner. Droplet microfluidic chips can generate, manipulate, and sort individual droplets at kilohertz rates in a user-defined microchannel geometry, allowing new strategies for high-throughput screening and evolution of biomolecules. In this review, we discuss directed evolution studies in which droplet-based microfluidic systems were used to screen and improve the functional properties of biomolecules. We provide a systematic overview of basic on-chip fluidic operations, including reagent mixing by merging continuous fluid streams and droplet pairs, reagent addition by picoinjection, droplet generation, droplet incubation in delay lines, chambers and hydrodynamic traps, and droplet sorting techniques. Various microfluidic strategies for directed evolution using single and multiple emulsions and biomimetic materials (giant lipid vesicles, microgels, and microcapsules) are highlighted. Completely cell-free microfluidic-assisted in vitro compartmentalization methods that eliminate the need to clone DNA into cells after each round of mutagenesis are also presented.
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Affiliation(s)
- Goran T Vladisaljević
- Department of Chemical Engineering, Loughborough University, Loughborough LE11 3TU, UK
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Thakur R, Weitz D. Manipulating the duration of picoinjection controls the injected volume of individual droplets. BIOMICROFLUIDICS 2024; 18:044102. [PMID: 38966806 PMCID: PMC11221878 DOI: 10.1063/5.0206830] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 03/04/2024] [Accepted: 06/21/2024] [Indexed: 07/06/2024]
Abstract
The ability to add reagents into droplets is required in many microfluidic workflows. Picoinjection can address this need; however, it is unable to control the injection volume for each individual droplet. Here, we present an improved picoinjection method that can inject controlled volumes into individual droplets. We achieve this by adjusting the injection duration for each picoinjection event. This improved picoinjection method can be used to create complex microfluidic workflows that are able to control the biochemical composition of individual droplets.
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Affiliation(s)
| | - D. Weitz
- Author to whom correspondence should be addressed:
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Verbist W, Breukers J, Sharma S, Rutten I, Gerstmans H, Coelmont L, Dal Dosso F, Dallmeier K, Lammertyn J. SeParate: multiway fluorescence-activated droplet sorting based on integration of serial and parallel triaging concepts. LAB ON A CHIP 2024; 24:2107-2121. [PMID: 38450543 DOI: 10.1039/d3lc01075a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 03/08/2024]
Abstract
Fluorescence-activated droplet sorting (FADS) has emerged as a versatile high-throughput sorting tool that is, unlike most fluorescence-activated cell sorting (FACS) platforms, capable of sorting droplet-compartmentalized cells, cell secretions, entire enzymatic reactions and more. Recently, multiplex FADS platforms have been developed for the sorting of multi-fluorophore populations towards different outlets in addition to the standard, more commonly used, 2-way FADS platform. These multiplex FADS platforms consist of either multiple 2-way junctions one after the other (i.e. serial sorters) or of one junction sorting droplets in more than 2 outlets (i.e. parallel sorters). In this work, we present SeParate, a novel platform based on integrating s̲e̲rial and p̲a̲r̲allel sorting principles for accura̲t̲e̲ multiplex droplet sorting that is able to mitigate limitations of current multiplex sorters. We show the SeParate platform and its capability in highly accurate 4-way sorting of a multi-fluorophore population into four subpopulations with the potential to expand to more. More specifically, the SeParate platform was thoroughly validated using mixed populations of fluorescent beads and picoinjected droplets, yielding sorting accuracies up to 100% and 99.9%, respectively. Finally, transfected HEK-293T cells were sorted employing two different optical setups, resulting in an accuracy up to 99.5%. SeParate's high accuracy for a diverse set of samples, including highly variable biological specimens, together with its scalability beyond the demonstrated 4-way sorting, warrants a broad applicability for multi-fluorophore studies in life sciences, environmental sciences and others.
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Affiliation(s)
- Wannes Verbist
- Department of Biosystems - Biosensors Group, KU Leuven, Willem de Croylaan 42, Box 2428, 3001 Leuven, Belgium.
| | - Jolien Breukers
- Department of Biosystems - Biosensors Group, KU Leuven, Willem de Croylaan 42, Box 2428, 3001 Leuven, Belgium.
| | - Sapna Sharma
- Department of Microbiology, Immunology and Transplantation, Rega Institute, Laboratory of Virology and Chemotherapy, Molecular Vaccinology and Vaccine Discovery, KU Leuven, 3000 Leuven, Belgium
| | - Iene Rutten
- Department of Biosystems - Biosensors Group, KU Leuven, Willem de Croylaan 42, Box 2428, 3001 Leuven, Belgium.
| | - Hans Gerstmans
- Department of Biosystems - Biosensors Group, KU Leuven, Willem de Croylaan 42, Box 2428, 3001 Leuven, Belgium.
| | - Lotte Coelmont
- Department of Microbiology, Immunology and Transplantation, Rega Institute, Laboratory of Virology and Chemotherapy, Molecular Vaccinology and Vaccine Discovery, KU Leuven, 3000 Leuven, Belgium
| | - Francesco Dal Dosso
- Department of Biosystems - Biosensors Group, KU Leuven, Willem de Croylaan 42, Box 2428, 3001 Leuven, Belgium.
| | - Kai Dallmeier
- Department of Microbiology, Immunology and Transplantation, Rega Institute, Laboratory of Virology and Chemotherapy, Molecular Vaccinology and Vaccine Discovery, KU Leuven, 3000 Leuven, Belgium
| | - Jeroen Lammertyn
- Department of Biosystems - Biosensors Group, KU Leuven, Willem de Croylaan 42, Box 2428, 3001 Leuven, Belgium.
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Zhu L, Tang Q, Mao Z, Chen H, Wu L, Qin Y. Microfluidic-based platforms for cell-to-cell communication studies. Biofabrication 2023; 16:012005. [PMID: 38035370 DOI: 10.1088/1758-5090/ad1116] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2023] [Accepted: 11/30/2023] [Indexed: 12/02/2023]
Abstract
Intercellular communication is critical to the understanding of human health and disease progression. However, compared to traditional methods with inefficient analysis, microfluidic co-culture technologies developed for cell-cell communication research can reliably analyze crucial biological processes, such as cell signaling, and monitor dynamic intercellular interactions under reproducible physiological cell co-culture conditions. Moreover, microfluidic-based technologies can achieve precise spatial control of two cell types at the single-cell level with high throughput. Herein, this review focuses on recent advances in microfluidic-based 2D and 3D devices developed to confine two or more heterogeneous cells in the study of intercellular communication and decipher the advantages and limitations of these models in specific cellular research scenarios. This review will stimulate the development of more functionalized microfluidic platforms for biomedical research, inspiring broader interests across various disciplines to better comprehend cell-cell communication and other fields, such as tumor heterogeneity and drug screening.
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Affiliation(s)
- Lvyang Zhu
- Nantong Key Laboratory of Public Health and Medical Analysis, School of Public Health, Nantong University, No. 9, Seyuan Road, Nantong 226019, Jiangsu, People's Republic of China
| | - Qu Tang
- Nantong Key Laboratory of Public Health and Medical Analysis, School of Public Health, Nantong University, No. 9, Seyuan Road, Nantong 226019, Jiangsu, People's Republic of China
| | - Zhenzhen Mao
- Nantong Key Laboratory of Public Health and Medical Analysis, School of Public Health, Nantong University, No. 9, Seyuan Road, Nantong 226019, Jiangsu, People's Republic of China
| | - Huanhuan Chen
- Nantong Key Laboratory of Public Health and Medical Analysis, School of Public Health, Nantong University, No. 9, Seyuan Road, Nantong 226019, Jiangsu, People's Republic of China
| | - Li Wu
- Nantong Key Laboratory of Public Health and Medical Analysis, School of Public Health, Nantong University, No. 9, Seyuan Road, Nantong 226019, Jiangsu, People's Republic of China
| | - Yuling Qin
- Nantong Key Laboratory of Public Health and Medical Analysis, School of Public Health, Nantong University, No. 9, Seyuan Road, Nantong 226019, Jiangsu, People's Republic of 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] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2022] [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)
| | | | | | | | - Florian Hollfelder
- Department of Biochemistry, University of Cambridge, 80 Tennis Court Rd, Cambridge CB2 1GA, U.K.
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