Semi-synthetic collagen/poloxamine matrices for tissue engineering

Collagen-containing poloxamine hydrogels were produced with the aim of overcoming the low stiffness displayed by collagen gels that are not otherwise chemically crosslinked. Matrices were obtained by functionalization of a four-arm PEO-PPO block copolymer (poloxamine, Tetronic™) with methcrylate groups and subsequent free radical polymerization of water solutions of the modified polymer in the presence of collagen. The resulting matrices had a sharp increase in stiffness, when compared to pure collagen gels. For example, whereas collagen had a storage modulus (G′) around 70 Pa and a loss modulus (G″) of 10 Pa, a crosslinked collagen/poloxamine system containing 8.3% crosslinked poloxamine had G′ and G″ values of 7400 and 1000 Pa, respectively. HepG2 cells were seeded within the gels before the crosslinking and the viability levels estimated by AlamarBlue™ assay were between 65% and 91% for systems containing 0.04–0.09 wt% photoinitiator. HepG2 and endothelial cells also adhered to and spread on the surface of the collagen-containing specimens, suggesting their potential utility in tissue engineering.