Sol-gel synthesis of silica/amylose composite particles with core–shell structure

Synthesized and characterized were silica/amylose composite particles with interesting morphologies which we named as silica/amylase composite core–shell particles. Amylose is soluble in hot water. Ethanol addition to a volume fraction fEtOH of 75% caused amylose to aggregate into globules with diameters ∼50 nm and smaller. After ammonia and tetraethoxysilane (TEOS) addition, TEOS underwent sol-gel reactions in the presence of amylose. The reactions eventually yielded core–shell nanospheres with their core enriched by amylose and shell consisting mostly of fused SiO2-wrapped amylose or SiO2@amylose nanoparticles. Under a given set of experimental conditions, the equilibrium nanospheres had a well-defined size. The shell thickness increased as mS/mA increased, where mS denoted the amount of SiO2 obtainable from the amount of TEOS precursor added and mA denoted the amylose amount. After pyrolysis of the nanospheres prepared at relatively high mS/mA values, interesting hollow silica particles with nano-sized porous walls were obtained.