Alginate based aerogels for life science applications

Aerogels are highly porous materials which make them interesting to be used as scaffolds in tissue engineering and regenerative medicine (TERM). Convenient route toward aerogels lies in gelation of low molecular weight precursors or biopolymers followed by supercritical drying. Due to the fact that gelation usually takes place in homogeneous mixtures, the high porosity of aerogels is mainly attributed to micro and mesopores (up to 100 nm). The main aim of this work is to present a novel approach to prepare macroporous aerogels by manipulating gelation at high pressure and drying conditions. Alginate based aerogels were produced in two step procedure. First, hybrid alginate-starch hydrogels were prepared by treatment of calcium carbonate suspension in alginate/starch solution under pressure. Then crosslinked hydrogels were subjected to stepwise solvent exchange for ethanol followed by supercritical drying with carbon dioxide (120 bar, 40° C, 5-6 h). The aerogels were characterized by SEM and micro-computed tomography. The mechanical properties of the aerogels were also characterized in compression mode. In vitro bioactivity tests in simulated body fluid up to 14 days were also carried out. A mouse fibroblast-like cell line (L929) was used as a model to evaluate the in vitro biological performance of the matrices. Cell seeding within 7 days demonstrated that the materials are non-cytotoxic and the cells are able to adhere and proliferate on the surface of the scaffolds.