Synthesis and characterization of hybrid cellulose-silica aerogels reinforced with collagen to be used as scaffolds in biomedical applications

Cellulose-silica aerogels are fascinating materials featuring high porosity, low density andbiocompatible properties that can be useful in many biomedical applications. However, their lack ofsufficient mechanical stability makes them inappropriate for some purposes. In our effort to producemore durable and stronger aerogels and to improve their absorption capacity, hydrolysed collagenwas used as a reinforcing agent. Collagen and cellulose were integrated into silica networks bymeans of the sol-gel process and then dried in supercritical conditions using CO2. Different amountsof cellulose and collagen were employed, and Ca(NO3)2e?4H2O and KH2PO4 were added to inducethe production of hydroxyapatite. Structural characterization tests (uniaxial compression, BETmethod, TGA curves, FTIR analyses, and SEM) conducted on the collagen-cellulose-silica aerogelsshowed that their compressive properties greatly exceed those of plain cellulose aerogels, and that,unlike the latter, the former exhibited elastomeric behaviour. Their absorption capacity propertieswere also measured by immersing them in simulated body fluid (SBF). Results proved that thestable structure and effective swelling of cellulose aerogels improved significantly by the use ofcollagen (swelling ratio from 80 to 96 %). Finally, the bioactivity of scaffolds was evaluated byexamining the formation of a biologically active carbonate apatite layer on its surface afterimmersion in SBF. These promising results led us to carry out cell adhesion/attachment tests, whichrevealed the presence of osteoblast cells on the scaffolds’ surface. We can conclude that theprepared cellulose/silica aerogels may be used as tissue engineering scaffolds.