Chitosan-silicate hybrids with 3D porous structures were prepared with freeze-drying precursor solutions derived from chitosan and gamma-glycidoxypropyltrimethoxysilane (GPTMS). They were formed easily in any shape, such as sheets, pellets, disks, granules, and even roll-cakes. The pore size was strongly dependent on the freezing temperature: lower freezing temperature resulted smaller pores, about 110 mu m for the hybrids frozen at -20 degrees C, and about 50 mu m for those at -85 degrees C. The pore size was little dependent on the GPTMS content. In contrast, the GPTMS content affected porosity a littlie: similar to 80% for chitosan, and similar to 90% for the GPTMS-containing hybrids. Thus, their porous microstructure was controllable due to the freezing temperature and composition. MG63 osteoblastic cells were cultured up to 7 days on the porous hybrids. The cells adhered on the pore walls, proliferated, and migrated deep into the pore structure. It was thus concluded that the present chitosan-silicate hybrids were promising for tissue engineering scaffold applications. (C) 2007 Elsevier B.V. All rights reserved.