Hexagonal Close-Packed Array Formed by Selective Adsorption onto Hexagonal Patterns

A patterned two-dimensional hexagonally ordered array of ferritin molecules, the outer surfaces of which had been genetically modified by titanium (Ti) specific binding peptides (minT1-LF), was realized in a self-assembling manner on a hexagonal Ti thin film island made on a silicon substrate. The optimum degree of order was realized at the pH with the maximum selectivity of minT1-LF adsorption on the Ti surface with respect to the silicon dioxide (SiO2) surface. Quartz crystal microbalance (QCM) measurement revealed that minT1-LF adsorbed onto the Ti surface strongly and irreversibly, but adsorbed onto the silicon dioxide surface weakly and reversibly. It was suggested that the concentration of minT1-LF on the Ti pattern promotes hexagonal close-packed ordering and axis aligning.