A method for making a patterned SiO.sub.2 films over TiO.sub.2 (Si0.sub.2/Ti0.sub.2) under ambient atmospheric conditions, including room temperature, through photo and chemical reactions. The method is simple, convenient and can be performed in a short period of time, typically less than two hours. The patterned TiO.sub.2 film is fabricated through photo-irradiation of a photosensitive organic-titanium film using a mask. Silica particles are generated from silicate solution by adjusting pH values to 10 to 8 with hydrochloric acid. The pre-deposited TiO.sub.2 film has a strong attraction for the SiO.sub.2 particles, leading to the instant formation of SiO.sub.2 film over the TiO.sub.2 film. The silica films are also amino-silylated with 3-aminopropyltriethoxysilane toward applications such as patternable, location-specific silica-based separation and purification.