The formation of silica nanostructures by several living organisms, such as diatoms or sponges, involves specific macromolecules that control the growth and the organization of silica nanoparticles. In order to investigate if a single molecular system could perform both particle size control and morphological template, gelatine thin films of various concentration and strength were prepared as biomimetic models and their reactivity towards sodium silicate aqueous solutions was studied. Simultaneous formation of silica particles in the nanometric and micrometric size range was observed. The former corresponds to colloids grown at the surface of the gelatine films and the latter to particles induced by gelatine chain brushes formed at the film/water interface. These results are in good agreement with well-known principles of biomineralization and suggest that multi-molecular systems, rather than single components, are responsible for biogenic silica nanostructure formation.