Amperometric biosensor for glutathione based on osmium-polyvinylpyridine gel polymer and glutathione sulfhydryl oxidase

A new amperometric biosensor based on glutathione sulfhydryl oxidase (GSH-S Ox) and osmium-poly/inylpyridine gel polymer (Os-gel-HRP) bilayer film modi fied glassy carbon (GC) electrode was demonstrated for glutathione (GSH) an d glutathione disulfide (GSSG). Os-gel-HRP was applied at glassy carbon (GC ) electrode with a surface coverage of 7.1 mu L/cm(2) to sense hydrogen per oxide based on horseradish peroxide (HRP) catalytic reaction mediated by os mium. GSH-SOx was immobilized at Os-gel-HRP cast coated GC electrode with a n approximate surface coverage of 7 U/cm(2) by cross-linking with BAS-GSH-S Ox in glutaraldehyde vapor for 5 min. The resultant bienzyme-based sensor w as tested toward GSH and GSSC with techniques of cyclic voltammetry (CV), f low cell amperometry and flow injection analysis (FIA). The sensor was pola rized at 0.0 V (versus Ag/AgCl, 3M KCl) electrode for the detection of GSH and GSSG in a flow system at a flow rate of 6 mu L/min. Linear response to GSH and GSSG in a concentration range from 1 mu M to 200 ItM and 7 mu M to 120 mu M was obtained at the sensor with a sensitivity of 1.195 nA/mu M and 0.60 nA/mu M for GSH and GSSG, respectively. The dependence of current res ponse on pH value of the buffer and operating potential was also tested and optimized.