Thermoresponsive and cytocompatible infernan-based hydrogels exhibiting poroelastic properties

Thermoresponsive polymers sensitive to temperature changes are particularly well adapted for applications in tissue engineering due to their in situ sol-gel transition at physiological temperature, enabling a rapid gel formation after injection. Infernan, a bacterial exopolysaccharide (EPS) of marine origin endowed with glycosaminoglycan-mimetic properties was grafted with a thermoresponsive polymer, poly(N-isopropylacrylamide) (pNIPAM) using carbodiimide chemistry. The resulting infernan-pNIPAM polymers were shown to form thermoresponsive hydrogels at physiological temperature. Their mechanical properties determined in fully hydrated state at 37 °C by Atomic Force Microscopy (AFM) through force-indentation and force-relaxation experiments revealed their poroelastic behavior. Based on AFM measurements, a set of mechanical parameters was extracted, including the elastic modulus, the solvent diffusion coefficient and the pore size. Cytocompatibility of hydrogels evaluated in 3D culture using HEK293 cells was impacted by polysaccharide amount within the hydrogel and the cross-linking density of the network. Elucidation of the structure-function relationship of infernan-pNIPAM hydrogels was essential for their further optimal use in cartilage engineering.