Gel–sol–gel thermo-gelation behavior study of chitosan–inorganic phosphate solutions

In present study, the feasibility of developing a novel thermo-sensitive hydrogel suitable for injectable formulations based on chitosan and inorganic phosphate was demonstrated. The physicochemical and rheological changes of chitosan/dibasic sodium phosphate solutions as in function with temperature were investigated in order to gain a better understanding of gelation process. According to the result of rheological study, there are two phase transition points as in function with temperature, corresponding to 30 °C and 43 °C. The system is gel state at ∼4 °C. With the temperature increased to 30 °C, the gel–sol transition as well as the decrease in turbidity was observed. The sol–gel transition as well as the increase in turbidity was observed again as the temperature was above 43 °C. And the gel obtained at ∼4 °C is reversible, but the gel obtained at ∼43 °C is irreversible.

Graphical abstractIn present study, a novel thermo-sensitive hydrogels suitable for injectable formulations based on chitosan and inorganic phosphate was demonstrated. The physicochemical and rheological changes of chitosan/dibasic sodium phosphate solutions were investigated in detail.Figure optionsDownload full-size imageDownload as PowerPoint slide