Fabrication of injectable hydrogels based on poly(l-glutamic acid) and chitosan

Injectable hydrogels as an important biomaterial class have been widely used in regenerative medicine. A series of injectable poly( l -glutamic acid)/chitosan (PLGA/CS) hydrogels were fabricated by self-crosslinking aldehyde-modified PLGA (PLGA-CHO) and lactic acid-modified chitosan (CS-LA). The oxidation degree of PLGA-CHO and degree of substitution (DS) of CS-LA could be adjusted by the amount of sodium periodate and lactic acid, respectively. The effect of the solid content of the hydrogels, oxidation degree of PLGA-CHO and CS-LA/PLGA-CHO mass ratio on the gelation time, gel content, water uptake, mechanical properties, microscopic morphology, and in vitro degradation of the hydrogels was examined. The pH and ion sensitivity of PLGA/CS hydrogels was also examined. Encapsulation of rabbit chondrocytes within the hydrogels showed viability of the entrapped cells and cytocompatibility of the injectable hydrogels. The injectable PLGA/CS hydrogels demonstrated attractive properties for future application in pharmaceutical delivery and tissue engineering. The in situ forming hydrogels based on oppositely charged poly( l -glutamic acid) (PLGA) and chitosan (CS) were prepared via a Schiff base crosslinking reaction.