Self-gelatinizable graft copolymer of poly(vinyl alcohol) with 4-vinylpyridine as an immobilization matrix for the construction of a tyrosinase-basedamperometric biosensor

A tyrosinase-based amperometric biosensor using a self-gelatinizable graft copolymer of poly(vinyl alcohol) with 4-vinylpyridine (PVA-g-PVP) as an imm obilization matrix was constructed. The 4-vinylpyridine component of PVA-g- PVP enhances the adherence to a glassy carbon electrode surface. The conten t of 4-vinylpyridine in this immobilization matrix plays a key role in reta ining the activity of tyrosinase. A simple, milder method was adopted by si mply syringing the copolymer-tyrosinase aqueous solution on to the electrod e surface and allowing water to evaporate at 4 degrees C in a refrigerator. Several parameters, including copolymer composition; pH, applied potential and enzyme membrane composition, ware optimized. The enzyme membrane compo sition can be varied to obtain higher sensitivity or a wider linear detecti on range. The biosensor was used for the determination of phenol, p-cresol and catechol. The biosensor exhibited excellent reproducibility, stability and sensitive response and can be used in flow injection analysis. The bios ensor showed an extended linear range in hydrophilic organic solvents and i t can be used in monitoring organic reaction processes. The analytical perf ormance demonstrated this immobilization matrix is suitable for the immobil ization of tyrosinase.