A phenol electrochemical biosensor based on immobilization of tyrosinase in silica sol-gel/alginate composite film

A new sol-gel-derived silicate/alginate inorganic-organic hybrid film was developed when the alginate was used as additive. The resulting composite film was applied to entrap tyrosinase for fabricating phenol biosensor. Firstly, a homogeneous stock methyltrimethoxysilane (MTMOS) /alginate was prepared by using MTMOS as the precursor and alginate as the additive. 0.3 mL of methanol, 0.2 mL of MTMOS. 0.2 mL of 10 g/L sodium alginate, and 0.2 mL of 0.01 mol/L HCl were mixed in a small weigh vial at room temperature and then sonicated for approximately 20 min to obtain a uniform soil. Sequently, 2 mg of tyrosinase was dissolved with 0.1 mL of tyrosinase solution and then was dropped onto the surface of the pro-treated glassy carbon electrode (GCE). The electrode was left to dry at 4 degrees C for 2 h. Lastly, 5 mu L of stock MTMOS/alginate sol was dropped to cover gyrosinase modified GCE obtaining phenol electrochemical biosensor. The results showed that silicate/alginate composite film could overcome brittleness of the pure sol-gel-derived silicate matrix and prevent its cracking and provide suitable microenvironment for enzyme and retaining its bioactivity to a large extent. A practically usable linear range for the phenol assay extends between 3.4 and 93.1 mu mol/L.