Oligo(L-lysine)-induced titanium dioxide: Effects of consecutive lysine on precipitation

Biomineralization of metal oxide utilizes biomolecular substances, such as peptides and proteins, to induce mineralization of metal precursors in a mild aqueous solution. In this study, we investigated biomineralization of an abiological substance, titanium dioxide (TiO₂), by oligo(L-lysine). Specifically, we systemically studied the influence of the number of consecutive lysine on TiO₂ precipitation. Oligo(L-lysine) was chosen as a homopeptide lysine source whose lysine quantity was adjusted. When oligo(L-lysine) contains more than three consecutive lysine, it induces notably fast precipitation, while single and dilysine do not readily form TiO ₂ precipitates. Precipitation of TiO₂ was promoted with the length of oligo(L-lysine). The oligo(L-lysine) was associated with TiO ₂ precipitate, which was confirmed by spectroscopic and thermogravitational analyses. The outcomes of this research provide a plausible rationale for explaining precipitation of the Ti precursor that is highly dependent on peptide sequences.