Synergistic interactions during thermosensitive chitosan-β-glycerophosphate hydrogel formation

Time-evolved gelation behavior of a chitosan-beta-glycerophosphate (CS/beta-GP) system was elucidated from rheological investigation, NMR analysis, fluorescence measurement, and morphology observation. Urea and isobutanol were selected to assess the interactions between the two components during the gelation process of the CS/beta-GP system. Urea was found to be detrimental to the gelation process by both disrupting hydrogen bonding and retarding the formation of hydrophobic domains. On the contrary, the addition of isobutanol accelerated the sol-gel transition by strengthening the hydrophobic interactions. These results reveal that both hydrogen bonding and hydrophobic interactions within chitosan or between chitosan and beta-glycerophosphate molecules are the main reasons for gel formation. The results also indicate that firstly the formation of hydrogen bonds makes the hydrophobic sites more accessible, and then the synergistic hydrogen bonding and hydrophobic interactions lead to the final formation of CS/beta-GP gel network. This work demonstrates the possibility of tuning the gelling ability as well as the mechanical properties of CS/beta-GP hydrogels. Thus, it gives the opportunities to optimize the performance of this promising natural thermosensitive material for practical applications in the future.