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Chitosan Solubility at low pH
I have Chitosan, with a deacetylation degree of at least 95% and a viscosity of 100-200 mPa.s. I tried to make a 10mg/ml solution in 1% acetic acid, which required 20 minutes of sonication to achieve solubility. Then, I tried to adjust the pH to 5.5 using 1N NaOH. However, upon adding a small portion of NaOH, hydrogels began to form, even at a pH of around 4.5. As I continued to raise the pH, more hydrogels formed, and the pH became inconsistent between the hydrogel and the rest of the solution. It’s important to note that the solution was constantly stirred using a stirring bar. I had expected Chitosan to be soluble at low pH. What would you suggest I do in this situation?
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3 Replies
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If you need to anyway raise the pH of your chitosan solution, perhaps a small addition of an inorganic salt could reduce inter and intramolecular interactions that produce the hydrogel to swell. Try first with a small amount of a monovalent salt.
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Thank you for your input. What concentration of monovalent salt would you recommend?
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I would start with 0.1%. Increase if needed, little by little.
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