The best solvent of  Chitosan is 1% acetic acid 

Thank you so much. I wanted to know both acidic and basic buffers as I am going do swelling study to use it in drug delivery

The isoelectric point (IEP) of chitosan can be expected within 7―9, while that of gum acacia should occur by 1―3. Within both IEP ranges, these molecules are oppositely charged, so that they tend to form mutual electrostatic complexes, while dissolved. Coacervation can occur by about the 3―6 pH range. Swelling should be maximized at some point within this same range.     

Thank you so much. I shall try to study swelling behavior in acidic buffer in the range 3-6. But I also need to do in a basic buffer too.