title: A sensor for superoxide in aqueous and organic/aqueous media based on immobilized cytochrome c on binary self-assembled monolayers.
abstract: A method for the electrochemical detection of superoxide radical was developed, based on cytochrome c (cyt c) immobilized on the binary self-assembled monolayers (SAMs) of thioctic acid (T-COOH) and thioctic amide (T-NH2) on gold electrode. The sensor works by electrochemically detecting cyt c reduced by the superoxide radical generated by a xanthine-XOD system. The electrochemical properties of immobilized cyt c were investigated in aqueous buffer and in a mixture of aqueous and organic solvents. The interaction of superoxide radical with the modified electrode was characterized in phosphate buffer solution (PBS) and in the mixtures of both PBS and dimethyl sulfoxide (DMSO) and PBS and glycerol (Gly). The results showed that the sensors responded immediately to superoxide radical in PBS and gave a steady-state anodic current within 10s during the generation of superoxide radical. In 40% DMSO and in 30% Gly solution, the current response reached a steady-state anodic current within 20s. The sensor could also be used to estimate superoxide dismutase (SOD).
authors.affiliation: Department of Medical Chemistry, Hebei Medical University, Shijiazhuang 050017, China. xpji03@yahoo.com.cn
authors.forename: Xueping
authors.initials: X
authors.lastname: Ji
authors.forename: Jujie
authors.initials: J
authors.lastname: Ren
authors.forename: Jiye
authors.initials: J
authors.lastname: Jin
authors.forename: Toshio
authors.initials: T
authors.lastname: Nakamura
mesh_terms: D015374:Biosensing Techniques / Q000295:instrumentation* / Q000379:methods; D020099:Coated Materials, Biocompatible / Q000737:chemistry; D045424:Complex Mixtures / Q000737:chemistry; D045304:Cytochromes c / Q000737:chemistry* / Q000648:ultrastructure; D004563:Electrochemistry / Q000295:instrumentation* / Q000379:methods; D004800:Enzymes, Immobilized / Q000737:chemistry; D004867:Equipment Design; D019544:Equipment Failure Analysis; D009930:Organic Chemicals / Q000737:chemistry*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D012997:Solvents / Q000737:chemistry; D013481:Superoxides / Q000032:analysis*; D013499:Surface Properties; D014867:Water / Q000737:chemistry*
chemical_list: D020099:Coated Materials, Biocompatible; D045424:Complex Mixtures; D004800:Enzymes, Immobilized; D009930:Organic Chemicals; D012997:Solvents; D014867:Water; D013481:Superoxides; D045304:Cytochromes c