INFIQC   05475
INSTITUTO DE INVESTIGACIONES EN FISICO- QUIMICA DE CORDOBA
Unidad Ejecutora - UE
artículos
Título:
Adsorption of Human Serum Albumin on Electrochemical Titanium Dioxide Electrodes: Protein-Oxide Surface Interaction Effects Studied by Electrochemical Techniques
Autor/es:
F. Y. OLIVA, O. R. CÁMARA AND L. B. AVALLE.
Revista:
JOURNAL OF ELECTROANALYTICAL CHEMISTRY
Editorial:
ELSEVIER
Referencias:
Año: 2009 vol. 633 p. 19 - 34
ISSN:
0022-0728
Resumen:
The adsorption of Human Serum Albumin (HSA) on a semiconductor TiO2 electrochemical oxide was investigated using Cyclic Voltammetry (CV), Capacity-Potential curves (C-E) and time - resolved techniques as a function of electrode potential and protein concentration. The presence of HSA adsorbed on the electrode surface modifies the voltamperometric behavior of the hydrogen evolution reaction (her) and also produces a major modification in the diffusional layer thickness of the H+ ions. The adsorbed amounts of HSA were analyzed throughout different adsorption isotherms. The experimental data were modeled with a modified Langmuir type isotherm, considering a weak chemisorption on a surface with heterogeneity in site-energy distribution with some degree of attractive lateral interactions between the adsorbed protein molecules. The effect of the adsorption potential (Eads) was investigated polarizing the electrode at -0.70, -0.50 and -0.08 V vs saturated calomel electrode (SCE) that corresponds to a more negative, similar to, and a more positive value than the flat band potential (Efb) of an electrochemical TiO2 oxide film, respectively. The capacity response obtained from the different impedance experiments was determined by the space charge region in the semiconductor. It was possible to correlate some processes produced by the protein adsorption on the surface (processes occurring in the electrolyte side of the electrode-solution interface) with changes in the semiconductor properties of the TiO2 oxide (changes occurring in the oxide side of the electrode-solution interface). The adsorption of HSA produces an increase in donor concentration (ND) of the semiconductor TiO2 oxide and a shift of the Efb to more negative values. Both of these effects are more pronounced with an increase in the protein concentration in solution. It was also observed that the relative change in ND is lower and the change in Efb is higher when the adsorption occurs to less negative applied potentials. Adsorption kinetics and thermodynamic parameters were calculated for a wide protein concentration range.