Collagen-templated sol-gel fabrication, microstructure, in vitro apatite deposition, and osteoblastic cell MC3T3-E1 compatibility of novel silica nanotube compacts

Silica sol particles were coated on collagen fibrils at room temperature as they were soaked in a Stober type precursor system, consisting of tetraethoxysilane-ethanol-water-ammonium hydroxide, with or without CaCl2. Calcination of the fibrils at 600 degrees C led to silica nanotube compacts of cm size. Transmission electron microscope analysis indicated that they consisted of hollow silica nanotubes, where the shell thickness and roughness increased with the calcium content. The Ca-containing compacts were active to depositing petal-like apatite crystallites when soaked in Kokubo's simulated body fluid. Moreover, they enhanced proliferation and differentiation of osteoblast MC3T3-E1 cells, even produced collagen fibrils.