The formation of nanofilm deposits of TiO2 nanoparticle phytates based on the directed assembly methodology  is demonstrated. Alternant exposure of a tin-doped indium oxide (ITO) or gold electrode surface to aqueous solutions of TiO2 nanoparticles (3-4 % in HNO3, ca. 6 nm diameter) and phytic acid (40 mM, at pH=3) causes layer-by-layer growth of a three dimensional mesoporous structure.
Cytochrome c in aqueous phosphate buffer (pH=7) is readily accumulated into the mesoporous TiO2 phytate film predominantly due to electrostatic binding of the positively charged protein to the negatively charged interfacial phytic acid . Voltammetric data for the reversible reduction and re-oxidation of cytochrome c suggest strong adsorption and ideal thin film behaviour over a wide range of conditions. Voltammetric and quartz crystal microbalance data are presented for accumulation and electrochemically driven desorption of Ru(NH3)63+ .
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