Scanning electrochemical microscopy of living cells: Different redox activities of nonmetastatic and metastatic human breast cells

Electrochemical methods have been widely used to monitor physiologically im portant molecules in biological systems. This report describes the first ap plication of the scanning electrochemical microscope (SECM) to probe the re dox activity of individual living cells. The possibilities of measuring the rate and investigating the pathway of transmembrane charge transfer are de monstrated. By this approach, significant differences are detected in the r edox responses given by nonmotile, nontransformed human breast epithelial c ells, breast cells with a high level of motility (engendered by overexpress ion of protein kinase C alpha), and highly metastatic breast cancer cells. SECM analysis of the three cell lines reveals reproducible differences with respect to the kinetics of charge transfer by several redox mediators.