Facile synthesis of agarose-L-phenylalanine ester hydrogels

Hydrogel forming agarose-L-phenylalanine ester (Ag-PA(Est)) was synthesized in a facile microwave mediated method involving the reaction of agarose with fluorenyl methyloxycarbonyl (Fmoc) protected amino acid L-phenylalanine (PA) in the presence of dicyclohexylcarbodiimide/4-dimethylaminopyridine (DCC/DMAP) followed by deprotection. Subsequently, the ester was crosslinked with the natural cross-linker genipin to yield a blue hydrogel (G-Ag-PA(Est)). Both the ester and cross-linked hydrogels had comparable gelling characteristics with agarose. These hydrogels were highly stable in all pH media (pH 1.2, 7.0 and 12.5) under ambient conditions. Physicochemical characterizations of the hydrogels were done by GPC, UV spectrophotometry, FT-IR, H-1- and C-13-NMR spectra. These hydrogels may have potential applications in microbiology, biomedical and pharmaceuticals fields.