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 (Pt(nano)/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/Pt(nano)/Au and GOx-APTES-CS/Au electrodes can be used to detect the enzymatically generated H(2)O(2) at 0.5 and 0.7 V vs SCE, respectively. The enzyme electrodes exhibited linear responses to glucose concentration from 0.2 mu M to 8.2 mM (R = 0.998, at Pt(nano)/Au substrate) and from 0.2 mu M to 5.5 mM (R = 0.998, at Au substrate), with current sensitivities of 69.5 (Pt(nano)/Au) and 65 (Au) mu A mM(-1) cm(-2), respectively, and a detection limit of 0.2 mu M (S/N = 3) was achieved for each electrode. The response time was less than 5 (Pt(nano)/Au) or 8 (Au) s. It is striking that the enzyme electrodes remained their initial response sensitivity after storage for 5 (Au) and >6 (Pt(nano)/Au) months in 0.10 M PBS (pH 7.0) at 4 degrees C. (C) 2011 Elsevier B.V. All rights reserved.