Electrochemical and bioelectrocatalytical properties of polydimethylsiloxane carbon paste doped with glucose oxidase

The carbon paste electrodes (CPE) based on a mixture of graphite (C) and polydimethylsiloxane (PDMSi) were prepared. Effects of carbon paste (CP) modification with a hardening agent (HA) and glucose oxidase (GO) on the heterogeneous electron transfer (ET) rate and the electrochemically active surface area were investigated using chronoamperometry and cyclic voltammetry of ferricyanide. luation of the chronoamperometric data permits one to conclude that the ET of ferricyanide at the CPE proceeds following the “pinhole” model. The surface coverage by the insulator and the radius of the pinholes depend on the CP nature and change from 0.88 to 0.69, and from 3.5 to 13.0 μm, respectively. The CPs comprising GO show larger electrode covering and a larger radius of pinholes, which was interpreted in relation to hydrophilization of modified graphite. erobic conditions oxidation of glucose with CP containing GO proceeds at a potential of 0.2 V vs. SCE, when ferricyanide was used as a soluble mediator. The calibration graphs of the electrodes response show a slightly sigmoidal character and are saturated at 40 mM of glucose. The electrode response depends on the enzyme amount and the nature of the CP. The maximum current of the electrodes was 2.0, 2.7 and 4.5 μA cm−2 for HA-free CP containing 1, 2 and 5% of GO, respectively. The current decreases about two times after addition of 1% hardening agent that is related to limited enzyme inactivation.