Biodegradable chitosan-chondroitin sulfate sponge for the controlled released of basic fibroblast growth factor

A new type of chondroitin sulfate (ChS)-chitosan (ChI) polyelectrolyte complex (PEC) sponge for controllable basic fibroblast growth factor (bFGF) release has been prepared by the methods of homogenizing interpolyelectrolyte complex. Since chondroitin sulfate is a recognized bFGF-binding glycosaminoglycan, and is very soluble in water, the ChS-ChI PEC sponges were crosslinked with glutaraldehyde, EDC/NHS and calcium ions respectively to prepare covalent- and ioniccrosslinked polymer networks. The stability, and in vitro enzymatic degradability and cytotoxicity of the glutaraldehyde-, EDC- and Ca²⁺-crosslinked ChS-ChI PEC sponges were all investigated in this study. The resuls showed that crosslinking improved the stability of prepared ChS-ChI PEC sponges, and provided more protective effect against the dissolution and enzymatic hydrolysis of fixed chondroitin sulfate, as compared to their non-crosslinked counterpart. However, we found that the ionic-crosslinking of ChS-ChI PEC sponges with calcium ions impaired the cell proliferation, suggested that cytotoxicity might be induced by calcium ions. To evaluate the conjugation interaction of bFGF with the ChS-ChI PEC sponges, the effects for the adsorption of bFGF to original and crosslinked-ChS-Chl PEC sponges were examined by ELISA studies. The bFGFconjugated ChS-ChI PEC sponges demonstrated different bFGF release pattern by the variation of crosslinking methods in a concentration-dependent way. The initial burst release could be eliminated due to the ChS-ChI interpolyelectrolyte complex and the crosslinking effect. These results suggest that the modified ChS-ChI PEC sponges may be beneficial to control the bFGF-releasing thus enhances the application potential of the bFGF-conjugated biomaterial for wound repair or tissue engineering.