Potential-assisted adsorption of bovine serum aAlbumin onto optically-transparent carbon electrodes

TOMÁS E. BENAVIDEZ; CARLOS D. GARCIA

San Antonio, Texas

Conferencia; College of Sciences, Research Conference; 2013

The University of Texas at San Antonio

This work describes the effect of the applied potential on the adsorption of bovine serum albumin (BSA) to optically transparent carbon electrodes. To decouple the effect of the applied potential from the high affinity of the protein for the bare iurface, the surface of the OTCE was initially saturated with a layer of BSA. Experiments show that potential values higher than 500 mV induced a secondary adsorption process (not observed at open-circuit potentials), yielding significant chinges in the thickness (and adsorbed amount) of the BSA layer obtained. Although the process showed a significantdependence on the experimental conditions selected, the application of higher potentials, selection of pH values around the isoelectric point (IEP) of the proteiry high concentrations of proteiry and low ionic strengths yielded faster kinetics and the accumulation of larger amounts of protein on the substrate. These experiments, obtained around the IEP of the protein, contrast with the traditional hypothesis that enhanced electrostatic interactions between the polarized substrate and the (oppositely charged) protein are responsible for the enhanced adsorption. According to our results, the potential appliedto the electrode is able to polarize the adsorbed layer and induce dipole-dipole interactions between the adsorbed and the incoming protein. This is the first report describing the mechanism responsible for the potential-dependent oversaturation of the suiface that could bolster to the development of surfaces with enhanced catalytic activity and implants with improved biocompatibility.