Surface Free Energy Activated High-Throughput Cell Sorting

Abstract

Cell sorting is an\nimportant screening process in microbiology,\nbiotechnology, and clinical research. Existing methods are mainly\nbased on single-cell analysis as in flow cytometric and microfluidic\ncell sorters. Here we report a label-free bulk method for sorting\ncells by differentiating their characteristic surface free energies\n(SFEs). We demonstrated the feasibility of this method by sorting\nmodel binary cell mixtures of various bacterial species, including <i>Pseudomonas putida</i> KT2440, <i>Enterococcus faecalis</i> ATCC 29212, <i>Salmonella</i> Typhimurium ATCC 14028,\nand <i>Escherichia coli</i> DH5α. This method can\neffectively separate 10¹⁰ bacterial cells within 30 min.\nIndividual bacterial species can be sorted with up to 96% efficiency,\nand the cell viability ratio can be as high as 99%. In addition to\nits capacity of sorting evenly mixed bacterial cells, we demonstrated\nthe feasibility of this method in selecting and enriching cells of\nminor populations in the mixture (presenting at only 1% in quantity)\nto a purity as high as 99%. This SFE-activated method may be used\nas a stand-alone method for quickly sorting a large quantity of bacterial\ncells or as a prescreening tool for microbial discrimination. Given\nits advantages of label-free, high-throughput, low cost, and simplicity,\nthis SFE-activated cell sorting method has potential in various applications\nof sorting cells and abiotic particles.