Nanoparticles from chitosan

A process for forming a core shell polymer comprising forming a core by reacting one or more mono/di/tri or polycarboxylic acids or blends thereof with chitosan to form a first solution containing a chitosan nanoparticle that is partially crosslinked, wherein each of said carboxylic acids contains no vinyl group and wherein at least one of said carboxylic acids has at least two carboxyl groups thereon, said carboxyl groups forming an amide linkage between said carboxylic acid and said chitosan, and wherein said partially crosslinked nanoparticle core has a surface with one or more amino groups thereon;

• forming a shell on said core nanoparticle by reacting a water soluble carboxylic acid containing one or more vinyl groups with said amino groups on said surface of said partially crosslinked nanonparticle to form a second solution containing said core shell polymer, said vinyl carboxylic acid forming an amide linkage between said vinyl carboxylic acid and said amino groups on said surface of said core nanoparticle.