Silylated peptides as building blocks for material synthesis using sol-gel polymerization.

The bottom-up approach exploits simple building blocks to generate new materials with desired physical and chemical characteristics. Here, we combine two bottom-up routes that occur under mild conditions, self-assembly and sol-gel synthesis, to program the shape and structure of materials. While self-assembly occurs through non-covalent interactions, sol-gel synthesis involves forming covalent bonds. As a proof of concept, we chose the self-assembled peptide Phe-Phe and its fluorinated analogue Phe(4-F)-Phe(4-F) to template the sol-gel process. These peptides were silylated to allow their self-mineralization. Scanning electron microscopy and atomic force microscope analysis revealed the formation of rod-shaped structures for the silylated Phe-Phe while spherical particles were formed by its fluorinated analogue. The size of the particles ranges from nano to micron scale. Fourier transform infrared spectrometry suggested the presence of parallel β-sheet secondary structure and siloxane bond formation that can stabilize these structures. Overall this approach can be adopted for other self-assembled peptides for generating new materials using a bottom-up approach.