Complexes of chitosan and poly(methacrylic acid) studied by fluorescence techniques

Fluorescence techniques have been used to study the interactions of poly(methacrylic acid) (PMAA) with chitosan(CS) in aqueous solution. These studies show that PMAA and CS form complexes within a pH range of 3 to 10 and along with complexing with CS, the conformation of PMAA at pH 4 changed from a hypercoiled to a loose coiled form. However, this conformational change is not complete since the optimal ratio for the complex formation is 0.5:1(CS:PMAA, in residue unit). PMAA/CS complexes at pH 4 were largely disrupted with the addition of NaCl, most likely due to screening of the electrostatic attraction between ionized carboxyl groups of PMAA and protonated amino groups of CS.