Biosynthesis and characterization of cross-linked Fmoc peptide-based hydrogels for drug delivery applications

Recently, scientific and technological interest in the synthesis of novel peptide-based hydrogel materials have grown dramatically. Applications of such materials mostly concern the biomedical field with examples covering sectors such as drug delivery, tissue engineering, and production of scaffolds for cell growth, thanks to their biocompatibility and biodegradability. In this work we synthesized Fmoc-Phe3 based hydrogels of different chirality by using a biocatalytic approach. Moreover, we investigated the possibility of employing a crosslinker during the biosynthetic process and we studied and compared some chemico-physical features of both crosslinked and non-crosslinked hydrogels. In particular, we investigated the rheological properties of such materials, as well as their swelling ability, stability in aqueous medium, and their structure by SEM and AFM analysis. Crosslinked and non-crosslinked hydrogels could be formed by this procedure with comparable yields but distinct chemico-physical features. We entrapped dexamethasone within nanopolymeric particles based on PLGA coated or not with chitosan and we embedded these nanoparticles into the hydrogels. Dexamethasone release from such a nanopolymer/hydrogel system was controlled and sustained and dependent on genipin crosslinking degree. The possibility of efficiently coupling a drug delivery system to hydrogel materials seem particularly promising for tissue engineering applications, where the hydrogel could provide cells the necessary support for their growth, while nanoparticles could favor cell growth or differentiation by providing them the necessary bioactive molecules.