Influence of Nafion in Titania Sol-gel Matrix on Analytical Characteristic of Amperometric Phenol Biosensor Based on Tyrosinase.

For detection of phenolic compounds a simple amperometric biosensor based on tyrosinase immobilized in titania sol-gel/Nafion composite was employed. Titania sol-gel was mixed with Nafion (v/v) in ratios 1:1 (TiO2/NF-1/1) and 2:1 (TiO2/NF-2/1), v/v. Morphology of immobilization composites was characterized by scanning electron microscopy. Analytical performance of biosensors with Nafion and based only on titania sol-gel (TiO2) was compared. Apart from sensitivity, linear range and detection limit also repeatability, reproducibility and storage stability were evaluated. The biosensor based on titania sol mixed with Nafion in ratio 1:1 (v/v) exhibited the best analytical parameters in terms of sensitivity: 2.84 µA L µmol-1, corresponding LOD, 0.056 µmol L-1, and the long-term stability within 20 days: it retained 80% of initial activity.