ABSTRACT: Intracellular oxidation/reduction (redox) status is important in many cellular processes such as DNA synthesis, cell cycle progression, proliferation, differentiation, apoptosis and complex biomedical problems (e.g., tumorigenesis). Although the role of redox couples in biological process is important, the molecular mechanisms mediating redox sensitivity are poorly understood. Current methods to alter intracellular redox environment are often limited by selectivity. In order to circumvent these problems and to answer fundamental questions about the role of redox couples in cellular processes, we have devised a three-electrode electrochemical platform to study intracellular redox environment of Chinese Hamster Ovarian (CHO) using the glutathione/glutathione disulfide (GSH/GSSG) redox couple. This method enables control of the intracellular redox environment of CHO cells seeded on conductive surfaces. The use of flow cytometry and monochlorobimane (a membrane permeable probe that fluoresces in the UV spectrum upon reacting with GSH) has demonstrated that as the electric potential applied to cells becomes more negative the cellular GSH/GSSG balance shifts towards the reduced form, GSH. Furthermore, flow cytometry studies show that changes observed in redox environment are not due to cell death. We also propose to investigate the integration of redox sensitive biosensors inside CHO cells, which will allow in situ visualization of changes occurring as a function of applied potential. These studies willshed light on the relationship between intracellular redox couples and contact inhibition.