Gelation time and degradation rate of chitosan-based injectable hydrogel

Gelation time and degradation rate of thermallysensitive aqueous solutions of chitosan/Gp (glycerophosphate disodium salt) have been studied. The effects of different parameters such as Gp salt concentration, solution temperature, degree of deacetylation of chitosan (DDA) and drug loading on the gelation time have been investigated. Gravimetric analysis, gel permeation chromatography and FTIR spectrophotometry were used to investigate the influence of the DDA and concentration of chitosan solution on hydrogel degradation. The presented results indicated that gelation time decreases by increasing Gp salt concentration, temperature, concentration and DDA of chitosan solutions, while drug loading has no significant effect on gelation time. Slower degradation profile was recorded for hydrogel with the higher DDA and concentration of chitosan in the primary solution. FTIR studies indicated that the chemical structure of chitosan macromolecules does not change significantly during the degradation. It could be concluded that biodegradation of chitosan hydrogel occurred via its surfaces.