Hi folks,

I'm trying to follow the procedure described by Malhotra, Meenakshi et al. from this article: “A novel method for synthesizing PEGylated chitosan nanoparticles: strategy, preparation, and in vitro analysis.” International journal of nanomedicine vol. 6 (2011): 485-94.

I'm trying to synthesize phthaloyl chitosan so that I can pegylate chitosan through the hydroxyl group.

Briefly, in the first step fully deacetylated chitosan is prepared by treating the polymer with a concentrated NaOH solution. In the second step, deacetylated chitosan is added to a solution of phtalic anhydride in DMF. The reaction is stirred and mixed for 8 hours at 120°C under inert atmosphere.

I did as described and I have the feeling that the reaction didn't took place. The solution remained turbid and chitosan didn't undergo dissolution.

Is it possible to dissolve fully deacetylated chitosan in DMF at high temperature?

I can give you some additional information:

-I'm using anhydrous DMF, even though it is not strictly necessary (as it is described by Kurita et al. in Biomacromolecules, Vol. 3, No. 1, 2002)

-I'm using LMW chitosan by Sigma-ALdrich, the same used by Malhotra et al.

-I usually prepare chitosan in acidic aqueous solutions. Do you think that dissolving chitosan in aqueous solutions (CH3COOH 1%) prior to the addition could compromise/help the reaction? I don't want the anhydride to turn into phtalic acid.

Thanx in advance