A novel ultralow conductivity electromanipulation buffer improves cell viability and enhances dielectrophoretic consistency

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.

Dielectrophoretic Traps for Efficient Bead and Cell Trapping and Formation of Aggregates of Controlled Size and Composition

“…Indeed the presence of an electric field in a conductive media induces Joule heating. This effect can be mitigated by reducing the conductivity of the medium and correcting for osmolarity with the addition of dextrose or sucrose, but prolonged exposition of cells to such diluted media can alter their function and health ( Hyler et al (2021) ). As both electrodes configurations presented here create a three dimensional DEP trap against the flow, we selected the most efficient configuration by measuring the magnitude of the DEP force against the flow for both configurations and evaluated in both cases the induced temperature rise.…”

A High-Throughput Microfluidic Cell Sorter Using a Three-Dimensional Coupled Hydrodynamic-Dielectrophoretic Pre-Focusing Module

“…In the next step, to avoid unwanted cell adhesion to electrodes and clogging at the shallow constriction at the flow-focusing region, 5% bovine serum albumin (BSA) in filtered MQ water was pumped into the chip at 10 µL/min for 30 min to coat the surface of IDA electrodes and channel walls. The chip was then washed with an ultralow conductive (~85 µS/cm) DEP buffer [51] (CytoRecovery ® , Blacksburg, VA, USA) at 10 µL/min for 10 min to remove any remaining BSA solution. To perform sorting, the cells were suspended in DEP buffer with a concentration of 1 × 10 6 cells/ml right before the experiments and introduced into the chip.…”

Design and development of keratin/chitosan/glucosamine sulfate composite loaded MWCNT intended for osteoarthritis drug delivery

“…For control groups (three wells), the cells grown in the medium were seeded into a 96-well plate at a density of 50 000 cells/well, and for exposure groups (21 wells), the cells were retrieved each time suspended in their respective native media. Then they were subsequently seeded at a density of 50 000 cells/well [36].…”