Control of selective adsorption behavior of Ti-binding ferritin on a SiO2 substrate by atomic-scale modulation of local surface charges

We have systematically investigated the influence of local surface potential distribution on selective adsorption of Ti-binding ferritin (TBF) on SiO2 substrates. We found that the TBF exhibits the adsorption ability onto Ti-decorated SiO2 surface of less than one atomic layer coverage. This experimental finding enabled us to propose a model in which the positively charged sites and their nanometer-scale interval are the dominant factors that determine bond strength between TBF and SiO2 surfaces. Furthermore, on the basis of this model, the adsorption behavior of TBF onto bare SiO2 surfaces was controlled by generation and/or recovery of electrical defects in SiO2.