Continuous sheath-free separation of drug-treated human fungal pathogen Cryptococcus neoformans by morphology in biocompatible polymer solutions.

Cryptococcal meningitis caused by Cryptococcus neoformans is the leading cause of fungal central nervous system infections. Current antifungal treatments for cryptococcal infections are inadequate partly due to the occurrence of drug resistance. Recent studies indicate that the treatment of the azole drug fluconazole changes the morphology of C. neoformans to form enlarged "multimeras" that consist of three or more connected cells/buds. To analyze if these multimeric cells are a prerequisite for C. neoformans to acquire drug resistance, a tool capable of separating them from normal cells is critical. We extend our recently demonstrated sheath-free elasto-inertial particle separation technique to fractionate drug-treated C. neoformans cells by morphology in biocompatible polymer solutions. The separation performance is evaluated for both multimeric and normal cells in terms of three dimensionless metrics: efficiency, purity, and enrichment ratio. The effects of flow rate, polymer concentration, and microchannel height on cell separation are studied.