Enzymatically Crosslinked Ulvan Hydrogels as Injectable Systems for Cell Delivery

The present study represents a challenging effort aiming at converting the waste algal biomass Ulva sp. into a source of high added value materials for biomedical applications by means of a clean and sustainable process. Ulvan, a sulphated polysaccharide extracted from Ulva sp., is investigated as in situ gelling material by using the enzyme horseradish peroxidase as catalyst and H2O2 as reagent. The polysaccharide is successfully modified with tyramine units in order to be susceptible to enzymatic recognition and crosslinking through oxidative coupling. The times of gelation of ulvan-tyramine solutions are optimized by adjusting the amount of H2O2 used for ensuring their practical administration as injectable systems. The rheological properties of the polymeric solutions and the relevant hydrogels evaluated under operative conditions prove to be suitable as injectable in situ forming 3D-hydrogels. The preliminary biological assays evidence the full cytocompatibility of the developed hydrogels and their feasibility for being used as 3D-hydrogels for cell delivery.