Medium Size Enzyme Electrode Construction And Sensing Applications

1. Electrochemical study of a MeOHFc-mediated GOD bioelectrode based on Bi2O3/CS composite film and its application to biofuel cell.A novel Bi2O3nanoparticles were synthesized and applied to co-immobilize the ferrocenemethanol (MeOHFc) and glucose oxidase (GOD) with chitosan (CS) as complex matrix for the construction of enzyme-based bioelectrode. The GOD/Bi2O3/CS/MeOHFc-modified electrode exhibited a linear response to glucose over a concentration range of3.7×10-6-1.52×10-3M and a detection limit of1.7μM (S/N=3). Apparent Michaelis-Menten constant (KMapp) was calculated to be2.65mM. MeOHFc immobilized in Bi2O3/CS composite film played an effectively role as an electron shuttle and allowed the detection of glucose at0.25V (versus SCE). In addition, the application of the GOD/Bi2O3/CS/MeOHFc-based electrode as bioanode was investigated by associating with Pt and Laccase/Bi2O3/Laponite/ABTS-based electrode as biocathode. In0.1M PBS containing30mM glucose under ambient air, the assembled biofuel cell yielded the maximum power density of6μW cm-2at a cell votage of0.2V as well as an open-circuit voltage and a short-circuit current density of0.65V and53μA cm-2, respectively.2. Development of a BCB-mediated Tyrosinase bioelectrode based on CS-AuNPs/SWCNTs composite matrix and its application.Chitosan-gold nanoparticles (CS-AuNPs) were prepared by using basic chitosan suspension as reducing/stabilizing·agents. The obtained positively charged CS-AuNPs materials were attached to single-walled carbon nanotubes (SWCNTs) to form a CS-AuNPs/SWCNTs composite matrix. A Tyrosinase-based mediated bioelectrode was constructed, based on co-immobilization of brilliant cresyl blue (BCB) and Tyrosinase (Tyr) through electrostatic and π-π stacking interaction with the CS-AuNPs/SWCNTs composite matrix. BCB within the composite matrix acts as a highly efficient electron shuttle between the cathode and the enzymatically generated o-quinone. The PPO/CS-AuNPs/SWCNTs/BCB-modified electrode showed a sensitivity of1699mA M-1cm-2and a linear response range of5.0×10-8-2.0×10-5M for catechol in PBS. The Poly(BCB)-mediated Tyr electrode by electropolymerizing monoBCB onto the SWCNTs-modified GCE was also investigated, and it was found that the sensitivity was largely improved as compared to the BCB-mediated system.3. Development of a SWCNTs/PBCB modified G6PD bioelectrode and its application for the determination of G6P.This paper reports a three-dimensional nanocomposite of poly brilliant cresyl blue (PBCB) with single-walled carbon nanotubes (SWCNTs/PBCB) by electropolymerizing monoBCB onto the SWCNTs-modified GCE through the use of cyclic voltammetry. Scanning electron microscopy (SEM), UV-vis, FT-IR and cyclic voltammetry were used to characterize the PBCB/SWCNTs composite. A G6PD/SWCNTs/PBCB bioelectrode was developed by immobilizing glucose-6-phosphate dehydrogenase (G6PD) onto the SWCNTs/PBCB electrode surface by crosslinking with glutaraldehyde. The bioelectrode showed electrocatalytic activity toward the oxidation of glucose-6-phosphate (G6P) and it was successfully applied to the determination of G6P in amperometric mode at0.1V (vs. SCE). The results indicated that the biosensor exhibited excellent performance during G6P determination with a wide linear range (5μM-2.9mM), a fast response time (within10s), high sensitivity (32.8mA cm-2M-1) and a low detection limit (5μM, S/N=3).