Titania Binding Peptides as Templates in the Biomimetic Synthesis of Stable Titania Nanosols: Insight into the Role of Buffers in Peptide-Mediated Mineralization

In this Article, we report the unusual behavior of two peptides (Ti-1 (QPYLFATDSLIK) and Ti-2 (GHTHYHAVRTQT)) with high affinity for titania that efficiently promote titania mineralization from an aqueous titanium bisammonium lactatodihydroxide (TiBALDH) solution, yielding small (ca. 4 nm) titania nanoparticles. As a result, we were able to produce for the first time using a biomimetic approach highly stable sub-10-nm titania sols. Both sequences show a high titania mineralization activity per unit peptide concentration and a capacity to control particle size and stabilize nanoparticles through specific surface interactions. We also show that phosphate ions disrupt the controlled particle formation and stabilization achieved in the presence of the two peptides. The products obtained from phosphate buffered solutions are titanium-containing materials (not pure oxide) with poor morphological control similar to those previously reported by others. Our results provide important insights into understanding the mechanism of titania mineralization in a range of different aqueous media (water, Tris, and phosphate buffer).