Evaluation of desialylation effect on zeta potential of extracellular vesicles secreted from human prostate cancer cells by on-chip microcapillary electrophoresis

Extracellular vesicles including exosomes have the potential to be used in therapeutic and diagnostic applications. Towards the noninvasive diagnosis of prostate cancer using urinary exosomes, technical challenges lie in developing precise methods of analyzing exosomes. Previously, we developed an on-chip microcapillary electrophoresis (mu CE) system equipped with a laser dark-field microscope. The zeta potential of exosomes of cancer cells was found to be larger than that of normal cells. In this study, the zeta potential of exosomes of normal and cancer prostate cells was evaluated using this system after treating with sialidase. The large negative charge of cancer exosomes was found to be due to the large amount of sialic acids. These results suggest that an on-chip mu CE system is useful for the accurate evaluation of events that occur on the exosome surfaces at the single-particle level and promising for the prescreening of prostate cancer exosomes without the need for labeling. (C) 2014 The Japan Society of Applied Physics