title: Third-generation superoxide anion sensor based on superoxide dismutase directly immobilized by sol-gel thin film on gold electrode.
abstract: A third-generation biosensor for superoxide anion (O(2)*-) was developed based on superoxide dismutase (SOD) immobilized by thin silica-PVA sol-gel film on gold electrode surface. A rapid and direct electron transfer of SOD in the thin sol-gel film at the gold electrode was realized without any mediators or promoters. The characterization of the SOD electrodes showed a quasi-reversible electrochemical redox behavior with a formal potential of 80 + 5 mV (versus SCE) in 50 mmol l(-1) phosphate buffer solution (PBS), pH 7.0. The heterogeneous electron transfer rate constant was evaluated to be about 2.1s(-1). The anodic and cathodic transfer coefficients are 0.6 and 0.4, respectively. Based on biomolecular recognition for specific reactivity of SOD toward O(2)*- the SOD electrode was applied to a sensitive and selective measurement of O(2)*- with the low operation potential (-0.15 V versus SCE) in phosphate buffer solution, pH 7.0. The amperometric response was proportional to O(2)*- concentration in the range of 0.2-1.6 micromol l(-1) and the detection limit was 0.1 micromol l(-1) at a signal-to-noise ration of 3. The preparation of SOD electrode is easy and simple. The uniform porous structure of the silica-PVA sol-gel matrix results in a fast response rate of immobilized SOD and is very efficient for stabilizing the enzyme activity.
authors.affiliation: State Key Laboratory of Coordination Chemistry of China, Department of Chemistry, Nanjing University, Nanjing 210093, PR China.
authors.forename: Junwei
authors.initials: J
authors.lastname: Di
authors.forename: Shuping
authors.initials: S
authors.lastname: Bi
authors.forename: Ming
authors.initials: M
authors.lastname: Zhang
mesh_terms: D015374:Biosensing Techniques / Q000295:instrumentation*; D004566:Electrodes; D006046:Gold; D013482:Superoxide Dismutase; D013481:Superoxides / Q000032:analysis*
chemical_list: D013481:Superoxides; D006046:Gold; D013482:Superoxide Dismutase