Biomimetic Synthesis of Titanium Dioxide Utilizing the R5 Peptide Derived from Cylindrotheca fusiformis

Abstract

Current approaches to the synthesis of metal oxides generally require harsh conditions. In contrast, many biological processes can produce intricate metal oxide nanostructures under ambient conditions. For example, the diatom Cylindrotheca fusiformis forms reproducible nanostructures from silicic acid using species specific peptides known as silaffins. Herein, we report that the R5 peptide a bioinspired analogue derived from the NatSil protein in C. fusiformis can form titanium dioxide (TiO2) in a concentration dependent manner from the non-natural substrate, titanium bis(ammonium lactato)dihydroxide. Additionally, the polypeptide poly(l-lysine) acts as a template for the biomimetic synthesis of TiO2. Subsequently, the nanoparticles were characterized using scanning electron microscopy, energy-dispersive X-ray spectrometry, and IR spectroscopy. A variable temperature X-ray diffraction study of the titanium dioxide phase transition from anatase to rutile was conducted. A delay in transition temperature was observed with titanium dioxide synthesized in the presence of phosphate buffer.