Zifeng, D; Qi, R; Xia, Y; Haiqing, L; Yang, T
Here, we report on a novel superoxide anion (O2•-) biosensor based on direct electron transfer of copper, zinc-superoxide dismutase (Cu, Zn-SOD) at zinc oxide nanodisks surface for in vivo tracking of O2•- in bean sprouts. Direct electron transfer of SOD is achieved at ZnO nanodisks film prepared by a one-step electrodeposited method, with a high heterogeneous electron rate constant of 17 ± 2 s-1. Spectroscopic data demonstrate that SOD strongly immobilized onto the nanostructured ZnO surfaces processes its inherent activity toward O2•- dismutation. A combination of the facilitated direct electron transfer and the bifunctional enzymatic catalytic activities of the SOD substantially provides a dual elecIrochemical approach to determination of O2•- with high selectivity, wide linear range, long stability, and good reproducibility. In particular, SOD adsorbed on the ZnO nanodisks film is capable of sensing O2•- cathodically at a very positive potential, 0 mV (vs Ag∣AgCl), where the common interfering species such as hydrogen peroxide, uric acid, ascorbic acid, and 3,4-dihydroxyphenylacetic acid were effectively avoided. The excellent analytical performance of the present O2•- biosensor, combined with the remarkable characteristics of nanostructured ZnO films, such as biocompatibility, ease of preparation, and facile to miniaturize, paves an electrochemical way for reliable and durable in vivo determination of O2•- in bean sprouts. [ABSTRACT FROM AUTHOR] Copyright of Analytical Chemistry is the property of American Chemical Society and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts)