https://doi.org/10.1016/j.ijbiomac.2020.06.287

Dear Vasigheh,

The pKa of the primary amine of chitosan is ~6.5, although it depends on the degree of N-deacetylation, so a first characterization of your polymer could give you some clues. If you observe precipitation using that PBS, it would mean that the pH of that PBS is too high for your chitosan. Hence you can try to modify the degree of deacetylation or use a water soluble chitosan such as carboxymethyl chitosan or lactate chitosan instead, for example.

Hope I've been of some help!

Best regards

Daniel Fernández-Villa

At this pH value, the chitosan (depending on its deacetylation degree) can crosslink itself and be used as gel for physicological environment as well.