Poly(brilliant cresyl blue) modified glassy carbon electrodes: Electrosynthesis, characterisation and application in biosensors

The phenoxazine dye, brilliant cresyl blue (BCB) has been polymerised on glassy carbon electrodes by potential cycling, and the resulting poly(brilliant cresyl blue) (PBCB) film has been studied by cyclic voltammetry, differential pulse voltammetry and electrochemical impedance spectroscopy. A differential pulse voltammetry study in different supporting electrolytes with different pH values revealed that the current intensity of the oxidation peak of the resulting polymer increases with increase in pH up to pH 4.1 where the highest response is exhibited and then begins to decrease. It was also observed that the peak potential moves to more negative values with increase in pH with a slope of −51 mV/pH, indicating an equal number of electrons and protons in the redox process. The electrode modified with poly(brilliant cresyl blue) was successfully applied to the determination of hydrogen peroxide in amperometric mode at 0.0 V vs. SCE. Glucose oxidase enzyme was then immobilised by crosslinking with glutaraldehyde and bovine serum albumin (BSA): the polymer functions as a redox mediator in a glucose biosensor allowing determination of glucose at small negative potentials with low interferences.