A sensitive mediator-free tyrosinase biosensor based on an inorganic–organic hybrid titania sol–gel matrix

A novel inorganic–organic hybrid titania sol–gel nanocomposite film was prepared to fabricate a sensitive tyrosinase biosensor for the amperometric detection of trace phenolic compounds without additional electron mediators. Acetylacetone worked as a complexing ligand to chelate with Ti atom in the synthesis process, and the pH of the titania solution could be adjusted to the value which was optimum for retaining tyrosinase activity and such a membrane was stably attached on to the surface of a glassy carbon electrode (GCE). This titania matrix could supply a good environment for enzyme loading, which resulted in a high sensitivity of 15.78 μA μM −1 cm −2 for monitoring phenols with a detection limit of 1×10 −8 M at a signal-to-noise ratio of 3. The TiO 2 sol–gel derived biosensor exhibited a fast response less than 10 s and a good stability for more than 2 months.