title: Direct electrochemistry of cytochrome c on a phosphonic acid terminated self-assembled monolayers.
abstract: The direct electrochemistry of cytochrome c (cyt c) on a gold electrode modified with 3-mercaptopropylphosphonic acid [HS-(CH(2))(3)-PO(3)H(2), MPPA] self-assembled monolayers (SAMs) was for the first time investigated. Electrochemical measurements and surface-enhanced infrared absorption spectroscopic reveal that the adsorption kinetics of cyt c on the MPPA-SAMs is very fast (saturation adsorption is completed within 5s) and the immobilized cyt c molecules retain their native secondary protein structure. The nature of interaction between cyt c and -PO(3)H(2) groups is mainly the electrostatic interaction. The direct electrochemistry of the immobilized cyt c on the -PO(3)H(2) terminated SAMs with short chain is nearly reversible. Its formal potential (E(0)'=18+/-3 mV vs. SCE) is very close to that of cyt c in an aqueous solution (E(0)'=18-22 mV vs. SCE). In addition, the electron transfer rate of cyt c immobilized on -PO(3)H(2) terminated SAMs is relatively slow as compared to -SO(3)H and -COOH terminated SAMs, indicating excess negative charge density on the SAMs surface will decrease the electron transfer rate of cyt c.
authors.affiliation: State Key Laboratory of Coordination Chemistry, Coordination Chemistry Institute, School of Chemistry and Chemical Engineering, Nanjing University, Nanjing, PR China.
authors.forename: Yu
authors.initials: Y
authors.lastname: Chen
authors.forename: Xiao-Jing
authors.initials: XJ
authors.lastname: Yang
authors.forename: Li-Rong
authors.initials: LR
authors.lastname: Guo
authors.forename: Bo
authors.initials: B
authors.lastname: Jin
authors.forename: Xing-Hua
authors.initials: XH
authors.lastname: Xia
authors.forename: Li-Min
authors.initials: LM
authors.lastname: Zheng
mesh_terms: D000327:Adsorption; D045304:Cytochromes c / Q000737:chemistry*; D004563:Electrochemistry / Q000379:methods*; D004566:Electrodes; D004579:Electron Transport; D007700:Kinetics; D063065:Organophosphonates / Q000737:chemistry*; D010084:Oxidation-Reduction; D013055:Spectrophotometry, Infrared
chemical_list: D063065:Organophosphonates; D045304:Cytochromes c