Cholesterol Oxidase/Triton X-100 Parked Microelectrodes for the Detection of Cholesterol in Plasma Membrane at Single Cells

The classic electrochemical analysis of plasma membrane cholesterol at single cells utilizes a cholesterol oxidase modified microelectrode that oxidizes local cholesterol efflux from the plasma membrane to generate hydrogen peroxide for the electrochemical quantification. In this letter, a mixture of cholesterol oxidase and Triton X-100 was filled in the microcapillary that could park at the Pt layer coated tip due to slow hydrodynamic flow. During the contact of the tip with the cellular membrane, Triton X-100 at the tip permeabilized the contacted membrane to release cholesterol for the reaction with cholesterol oxidase. As compared with the linkage of cholesterol oxidase at the electrode surface, the oxidase parked in aqueous solution at the tip had a higher turnover rate resulting in larger electrochemical signal for single cell analysis. More charge collected at acyl-coA:cholesterol acyltransferase (ACAT) inhibited cells supported that this novel detection strategy could monitor the flunctation of me...