Biomimetic synthesis of silica films directed by polypeptide brushes

Biomimetic porous silica films have been synthesized by polycondensation of tetraethoxysilane on a soft template formed by an "end-tethered poly(L-lysine)" ("t-PLL") monolayer with a brushlike configuration. The silica formation occurs spontaneously inside the t-PLL at neutral pH and room temperature. The growth of silica fully conforms to the original t-PLL film thicknesses and lateral micropatterns, regardless of a prolonged reaction time and the monomer concentration. The morphologies of biomimetic silica are changed from continuous pleated, discrete spherical to fibrous forms according to the initial t-PLL chain length and surface density. After the t-PLL template is burned off, TEM images show the creation of nanochannel arrays in silica with an average diameter of 10 nm. Overall, our approach has provided a straightforward and environmentally friendly route to directly generate silica films with controllable morphology, thickness, and porosity.