Biomimetic synthesis of silica with chitosan-mediated morphology

Biomimetic synthesis of silica with chitosan (CS)-mediated morphology was studied. The CS solution was first incubated for different periods of time, leading to different aggregation states. Some amount of prehydrolyzed tetraethylorthosilicate (TEOS) was then added and reacted for 12h. It was observed that various unique shapes of silica/CS hybrid particles were obtained. It was found that the silica shape was changed from spheres for as incubation time of 56 h for the CS solution, which may had grown from the silica nuclei of 1-2 nm diameter in the prehydrolyzed TEOS. An atomic force microscopy (AFM) observation verified that these distinguishable spherical particles were 20-40 nm in diameter. Organic additives were used as templates for silica formation during biosilification process. Silica particles were examined with a TS 5136MM scanning electron microscope at voltage of 20 kV, a Nanoscope atomic force microscope equipped with a 10-μm scanner under contact mode, and with a Hitachi-600 transmission electron microscope.