One-pot electrodeposition of 3-aminopropyltriethoxysilane–chitosan hybrid gel film to immobilize glucose oxidase for biosensing

We report on the electrodeposition of a 3-aminopropyltriethoxysilane-chitosan (APTES–CS) hybrid gel film for in situ immobilization of glucose oxidase (GOx) on an Au or platinized Au (Ptnano/Au) electrode for biosensing of glucose. Controllable electroreduction of p-benzoquinone is used to lift the electrode-surface pH for the GOx–APTES–CS codeposition, which was monitored by an electrochemical quartz crystal microbalance. The fabrication procedures of the biosensor and the parameters influencing the biosensing performance were optimized. The prepared porous GOx–APTES–CS/Ptnano/Au and GOx–APTES–CS/Au electrodes can be used to detect the enzymatically generated H2O2 at 0.5 and 0.7 V vs SCE, respectively. The enzyme electrodes exhibited linear responses to glucose concentration from 0.2 μM to 8.2 mM (R = 0.998, at Ptnano/Au substrate) and from 0.2 μM to 5.5 mM (R = 0.998, at Au substrate), with current sensitivities of 69.5 (Ptnano/Au) and 65 (Au) μA mM−1 cm−2, respectively, and a detection limit of 0.2 μM (S/N = 3) was achieved for each electrode. The response time was less than 5 (Ptnano/Au) or 8 (Au) s. It is striking that the enzyme electrodes remained their initial response sensitivity after storage for 5 (Au) and >6 (Ptnano/Au) months in 0.10 M PBS (pH 7.0) at 4 °C.