Sorting inactivated cells using cell-imprinted polymer thin films.

Previous work showed that cell imprinting in a poly(dimethylsiloxane) film produced artificial receptors to cells by template-assisted rearrangement of functional groups on the surface of the polymer thin film which facilitated cell capture in the polymer surface indentations by size, shape, and, most importantly, chemical recognition. We report here that inactivation of cells by treatment with formaldehyde (4%), glutaraldehyde (2%), or a combination of the two leads to markedly improved capture selectivity (a factor of 3) when cells to be analyzed are inactivated in the same manner. The enhanced capture efficiency compared to living cells results from two factors: (1) rigidification of the cell surface through cross-linking of amine groups by the aldehyde; and (2) elimination of chemicals excreted from living cells which interfere with the fidelity of the cell-imprinting process. Moreover, cell inactivation has the advantage of removing biohazard risks associated with working with virulent bacteria. These results are demonstrated using different strains of Mycobacterium tuberculosis.