XPS Analysis of Enzyme and Mediator at the Surface of a Layer-by-Layer Self Assembled Wired Enzyme Electrode

P. SCHODELLER; F. J. WILLIAMS; E. J. CALVO

ANALYTICAL CHEMISTRY

AMER CHEMICAL SOC

Lugar: Washington; Año: 2014 vol. 86 p. 12180 - 12184

0003-2700

High potential purified Trametes trogii laccase has beendeposited in mono- and multilayer thin films on gold surfaces by layer-bylayerelectrostatic adsorption self-assembly. The osmium bipyridil redox relaysites on polycation poly(allylamine) backbone efficiently work as a molecular?wire? in oxygen cathodes for biofuel cells. X-ray photoelectron spectroscopyof Cu 2p3/2 and Os 4f signals provided chemical information on the enzymeand redox mediator surface concentrations after different adsorption steps.The electrical charge involved in oxidation−reduction cycles of the osmiumsites, the ellipsometric enzyme film thickness, and the mass uptake fromquartz crystal microbalance experiments, correlate with the XPS surfaceconcentration, which provides unique evidence on the chemical identity ofthe composition in the topmost layers. XPS is shown to be an importantanalytical tool to investigate stratified copper and osmium distribution in LbLthin films relevant to biosensors and biofuel cells.