Enzyme-modified microelectrodes for electrochemical detection of sphingomyelin in the plasma membranes of single cells

Abstract

In this communication, sphingomyelin (SM) in the plasma membrane of single cells is detected electrochemically using an enzyme-modified Pt microelectrode for the first time. The enzymes immobilized at the electrode surface, which include sphingomyelinase (SMase), alkaline phosphatase (ALP), and choline oxidase, react with SM in a series of reactions to generate hydrogen peroxide. The electrochemical oxidation of hydrogen peroxide induces an elevation in the current, which offers a quantitative determination of SM in a range from 140 to 560 µM. Further contact of the microelectrode with one oocyte cell results in the reaction of SM in the plasma membrane with the enzymes at the electrode. The resulting current increase is correlated with the content of SM in the plasma membrane, confirming the electrochemical detection of membrane SM in single cells. This success in single cell electrochemical analysis of membrane SM expands the application of microelectrodes in single cell studies, which will help in the elucidation of cellular heterogeneity in lipid trafficking. Keywords: Enzyme-modified microelectrode, Sphingomyelin, Plasma membrane, Single cells, Cellular heterogeneity