Electrochemical behaviour of human serum albumin–TiO2 nanocrystalline electrodes studied as a function of pH: Part 1. Voltammetric response

The interaction of human serum albumin (HSA) with the surface of nanocrystalline Ti/TiO2 electrodes was studied using electrochemical techniques in 0.1 M NaCl at different solution pHs. The adsorbed protein layer that is formed immediately when the protein becomes in contact with the electrode was investigated as a function of solution pH and electrode potential. The surface electrochemical properties were studied by cyclic voltammetry in the presence and absence of HSA. The total charge of the voltammogram obtained at pH 3.5 shows a linear behaviour with the reciprocal of sweep rate from which the rate determining step of the Ti(IV)/Ti(III) process could be determined. The voltammetric charge values obtained in the presence of the protein suggested that the protein blocks part of the electrochemically active surface. The experimental results are explained with a model that takes into account both non-specific and specific protein/substrate interaction, which renders the system potential and solution pH dependent.