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Lapizco-Encinas BH. Nonlinear Electrokinetic Methods of Particles and Cells. ANNUAL REVIEW OF ANALYTICAL CHEMISTRY (PALO ALTO, CALIF.) 2024; 17:243-264. [PMID: 38360552 DOI: 10.1146/annurev-anchem-061622-040810] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/17/2024]
Abstract
Nonlinear electrokinetic phenomena offer label-free, portable, and robust approaches for particle and cell assessment, including selective enrichment, separation, sorting, and characterization. The field of electrokinetics has evolved substantially since the first separation reports by Arne Tiselius in the 1930s. The last century witnessed major advances in the understanding of the weak-field theory, which supported developments in the use of linear electrophoresis and its adoption as a routine analytical technique. More recently, an improved understanding of the strong-field theory enabled the development of nonlinear electrokinetic techniques such as electrorotation, dielectrophoresis, and nonlinear electrophoresis. This review discusses the operating principles and recent applications of these three nonlinear electrokinetic phenomena for the analysis and manipulation of particles and cells and provides an overview of some of the latest developments in the field of nonlinear electrokinetics.
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Affiliation(s)
- Blanca H Lapizco-Encinas
- Microscale Bioseparations Laboratory and Department of Biomedical Engineering, Rochester Institute of Technology, Rochester, New York, USA;
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Duncan JL, Schultz J, Barlow Z, Davalos RV. Introducing electric field fabrication: A method of additive manufacturing via liquid dielectrophoresis. ADDITIVE MANUFACTURING LETTERS 2023; 4:100107. [PMID: 36814549 PMCID: PMC9941962 DOI: 10.1016/j.addlet.2022.100107] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Biomedical devices with millimeter and micron-scaled features have been a promising approach to single-cell analysis, diagnostics, and fundamental biological and chemical studies. These devices, however, have not been able to fully embrace the advantages of additive manufacturing (AM) that offers quick prototypes and complexities not achievable via traditional 2D fabrication techniques (e.g., soft lithography). This slow adoption of AM can be attributed in part to limited material selection, resolution, and inability to easily integrate components mid-print. Here, we present the feasibility of using liquid dielectrophoresis to manipulate and shape a droplet of build material, paired with subsequent curing and stacking, to generate 3D parts. This Electric Field Fabrication (EFF) technique is an additive manufacturing method that offers advantages such as new printable materials and mixed-media parts without post-assembly for biomedical applications.
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Affiliation(s)
- Josie L. Duncan
- Bioelectromechanical Systems Laboratory, Department of Biomedical Engineering and Mechanics, Virginia Tech-Wake Forest University School of Biomedical Engineering and Sciences, Blacksburg VA, USA,Department of Mechanical Engineering, Virginia Tech, Blacksburg VA, USA,Corresponding author. (J.L. Duncan)
| | | | | | - Rafael V. Davalos
- Bioelectromechanical Systems Laboratory, Department of Biomedical Engineering and Mechanics, Virginia Tech-Wake Forest University School of Biomedical Engineering and Sciences, Blacksburg VA, USA,Department of Mechanical Engineering, Virginia Tech, Blacksburg VA, USA
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UV-Femtosecond-Laser Structuring of Cyclic Olefin Copolymer. Polymers (Basel) 2022; 14:polym14142962. [PMID: 35890739 PMCID: PMC9320777 DOI: 10.3390/polym14142962] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2022] [Revised: 07/15/2022] [Accepted: 07/18/2022] [Indexed: 02/04/2023] Open
Abstract
We report on the laser ablation of cyclic olefin copolymer using an amplified ultrashort pulsed laser in the ultraviolet spectral range. In addition to a high ablation depth per laser-structured layer up to 74 μm at a fluence of 22 J cm−2, an excellent mean roughness Ra of laser-patterned surfaces down to 0.5 μm is demonstrated. Furthermore, with increasing fluence, increasing ablation efficiencies up to 2.5 mm3 W−1 min−1 are determined. Regarding the quality of the ablation, we observed steep ablation flanks and low debris formation, though for fluences above 10.5 J cm−2 the formation of troughs was observed, being attributed to multiple reflections on the ablation flanks. For comparison, laser ablation was performed under identical conditions with an infrared laser wavelength. The results highlight that UV ablation exhibits significant advantages in terms of ablation efficiency, surface roughness and quality. Moreover, our results show that a larger UV focus spot accelerates the ablation process with comparable quality, paving the way for high-power UV ultrashort pulsed lasers towards an efficient and qualitative tool for the laser machining of cyclic olefin copolymer. The production of complex microfluidics further underlines the suitability of this type of laser.
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Hyler AR, Hong D, Davalos RV, Swami NS, Schmelz EM. A novel ultralow conductivity electromanipulation buffer improves cell viability and enhances dielectrophoretic consistency. Electrophoresis 2021; 42:1366-1377. [PMID: 33687759 DOI: 10.1002/elps.202000324] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2020] [Revised: 01/23/2021] [Accepted: 02/27/2021] [Indexed: 12/21/2022]
Abstract
Cell separation has become a critical diagnostic, research, and treatment tool for personalized medicine. Despite significant advances in cell separation, most widely used applications require the use of multiple, expensive antibodies to known markers in order to identify subpopulations of cells for separation. Dielectrophoresis (DEP) provides a biophysical separation technique that can target cell subpopulations based on phenotype without labels and return native cells for downstream analysis. One challenge in employing any DEP device is the sample being separated must be transferred into an ultralow conductivity medium, which can be detrimental in retaining cells' native phenotypes for separation. Here, we measured properties of traditional DEP reagents and determined that after just 1-2 h of exposure and subsequent culture, cells' viability was significantly reduced below 50%. We developed and tested a novel buffer (Cyto Buffer) that achieved 6 weeks of stable shelf-life and demonstrated significantly improved viability and physiological properties. We then determined the impact of Cyto Buffer on cells' dielectric properties and morphology and found that cells retained properties more similar to that of their native media. Finally, we vetted Cyto Buffer's usability on a cell separation platform (Cyto R1) to determine combined efficacy for cell separations. Here, more than 80% of cells from different cell lines were recovered and were determined to be >70% viable following exposure to Cyto Buffer, flow stimulation, electromanipulation, and downstream collection and growth. The developed buffer demonstrated improved opportunities for electrical cell manipulation, enrichment, and recovery for next generation cell separations.
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Affiliation(s)
| | - Daly Hong
- CytoRecovery, Inc., Blacksburg, VA, USA
| | - Rafael V Davalos
- Biomedical Engineering and Mechanics, Virginia Tech, Blacksburg, VA, USA
| | - Nathan S Swami
- Electrical and Computer Engineering, University of Virginia, Charlottesville, VA, USA
| | - Eva M Schmelz
- Biomedical Engineering and Mechanics, Virginia Tech, Blacksburg, VA, USA.,Human Nutrition, Foods and Exercise, Virginia Tech, Blacksburg, VA, USA
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Huang X, Torres-Castro K, Varhue W, Salahi A, Rasin A, Honrado C, Brown A, Guler J, Swami NS. Self-aligned sequential lateral field non-uniformities over channel depth for high throughput dielectrophoretic cell deflection. LAB ON A CHIP 2021; 21:835-843. [PMID: 33532812 PMCID: PMC8019514 DOI: 10.1039/d0lc01211d] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/21/2023]
Abstract
Dielectrophoresis (DEP) enables the separation of cells based on subtle subcellular phenotypic differences by controlling the frequency of the applied field. However, current electrode-based geometries extend over a limited depth of the sample channel, thereby reducing the throughput of the manipulated sample (sub-μL min-1 flow rates and <105 cells per mL). We present a flow through device with self-aligned sequential field non-uniformities extending laterally across the sample channel width (100 μm) that are created by metal patterned over the entire depth (50 μm) of the sample channel sidewall using a single lithography step. This enables single-cell streamlines to undergo progressive DEP deflection with minimal dependence on the cell starting position, its orientation versus the field and intercellular interactions. Phenotype-specific cell separation is validated (>μL min-1 flow and >106 cells per mL) using heterogeneous samples of healthy and glutaraldehyde-fixed red blood cells, with single-cell impedance cytometry showing that the DEP collected fractions are intact and exhibit electrical opacity differences consistent with their capacitance-based DEP crossover frequency. This geometry can address the vision of an "all electric" selective cell isolation and cytometry system for quantifying phenotypic heterogeneity of cellular systems.
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Affiliation(s)
- XuHai Huang
- Electrical & Computer Engineering, University of Virginia, Charlottesville, USA.
| | - Karina Torres-Castro
- Electrical & Computer Engineering, University of Virginia, Charlottesville, USA.
| | - Walter Varhue
- Electrical & Computer Engineering, University of Virginia, Charlottesville, USA.
| | - Armita Salahi
- Electrical & Computer Engineering, University of Virginia, Charlottesville, USA.
| | - Ahmed Rasin
- Electrical & Computer Engineering, University of Virginia, Charlottesville, USA.
| | - Carlos Honrado
- Electrical & Computer Engineering, University of Virginia, Charlottesville, USA.
| | - Audrey Brown
- Biology, University of Virginia, Charlottesville, USA
| | | | - Nathan S Swami
- Electrical & Computer Engineering, University of Virginia, Charlottesville, USA. and Chemistry, University of Virginia, Charlottesville, USA
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Honrado C, Bisegna P, Swami NS, Caselli F. Single-cell microfluidic impedance cytometry: from raw signals to cell phenotypes using data analytics. LAB ON A CHIP 2021; 21:22-54. [PMID: 33331376 PMCID: PMC7909465 DOI: 10.1039/d0lc00840k] [Citation(s) in RCA: 79] [Impact Index Per Article: 26.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/03/2023]
Abstract
The biophysical analysis of single-cells by microfluidic impedance cytometry is emerging as a label-free and high-throughput means to stratify the heterogeneity of cellular systems based on their electrophysiology. Emerging applications range from fundamental life-science and drug assessment research to point-of-care diagnostics and precision medicine. Recently, novel chip designs and data analytic strategies are laying the foundation for multiparametric cell characterization and subpopulation distinction, which are essential to understand biological function, follow disease progression and monitor cell behaviour in microsystems. In this tutorial review, we present a comparative survey of the approaches to elucidate cellular and subcellular features from impedance cytometry data, covering the related subjects of device design, data analytics (i.e., signal processing, dielectric modelling, population clustering), and phenotyping applications. We give special emphasis to the exciting recent developments of the technique (timeframe 2017-2020) and provide our perspective on future challenges and directions. Its synergistic application with microfluidic separation, sensor science and machine learning can form an essential toolkit for label-free quantification and isolation of subpopulations to stratify heterogeneous biosystems.
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Affiliation(s)
- Carlos Honrado
- Department of Electrical and Computer Engineering, University of Virginia, Charlottesville, VA 22904, USA.
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Ramirez-Murillo CJ, de Los Santos-Ramirez JM, Perez-Gonzalez VH. Toward low-voltage dielectrophoresis-based microfluidic systems: A review. Electrophoresis 2020; 42:565-587. [PMID: 33166414 DOI: 10.1002/elps.202000213] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2020] [Revised: 10/27/2020] [Accepted: 11/02/2020] [Indexed: 12/13/2022]
Abstract
Dielectrophoretically driven microfluidic devices have demonstrated great applicability in biomedical engineering, diagnostic medicine, and biological research. One of the potential fields of application for this technology is in point-of-care (POC) devices, ideally allowing for portable, fully integrated, easy to use, low-cost diagnostic platforms. Two main approaches exist to induce dielectrophoresis (DEP) on suspended particles, that is, electrode-based DEP and insulator-based DEP, each featuring different advantages and disadvantages. However, a shared concern lies in the input voltage used to generate the electric field necessary for DEP to take place. Therefore, input voltage can determine portability of a microfluidic device. This review outlines the recent advances in reducing stimulation voltage requirements in DEP-driven microfluidics.
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