title: Preparation and characterization of polyoxometalate/protein ultrathin films grown on electrode surfaces using layer-by-layer assembly.
abstract: We report a new electrostatic layer-by-layer assembly method for the controlled deposition of electrocatalytically active enzymes onto electrode surfaces using polyoxometalate as the counteranion. Cytochrome c (cyt c), a redox active protein, and P(2)W(18)O(62)(6-), a Dawson-type polyoxometalate, were deposited onto glassy carbon electrodes by two procedures: static dipping and electrochemical cycling. Cyclic voltammetry and UV-vis spectroscopy reveal that approximately 1.5 x 10(-10) mol/cm(2) of P(2)W(18)O(62)(6-) and 2.2 x 10(-11) mol/cm(2) of cytochrome c are deposited per cycle, which correspond to approximately one monolayer of each molecule. The thicknesses of the resulting films measured by atomic force microscopy also indicate that the films are formed in a layer-by-layer fashion. Experimental factors that affect electron-transfer rate in these films, such as scan rate and film thickness, were systematically analyzed. The use of {P(2)W(18)O(62)(6-)/cyt c}n films to catalyze hydrogen peroxide reduction was demonstrated.
authors.affiliation: Department of Chemistry and Biochemistry, Auburn University, Auburn, Alabama 36849, USA.
authors.forename: Kai
authors.initials: K
authors.lastname: Jiang
authors.forename: Hongxia
authors.initials: H
authors.lastname: Zhang
authors.forename: Curtis
authors.initials: C
authors.lastname: Shannon
authors.forename: Wei
authors.initials: W
authors.lastname: Zhan
mesh_terms: D000327:Adsorption; D002384:Catalysis; D045304:Cytochromes c / Q000737:chemistry; D004563:Electrochemistry / Q000295:instrumentation / Q000379:methods*; D004566:Electrodes; D006861:Hydrogen Peroxide; D011506:Proteins / Q000737:chemistry*; D055672:Static Electricity; D017973:Tungsten Compounds / Q000737:chemistry*; D000099294:Polyoxometalates
chemical_list: D045304:Cytochromes c; D006861:Hydrogen Peroxide; D011506:Proteins; D017973:Tungsten Compounds; C102296:polyoxometalate I; D000099294:Polyoxometalates