Preparation and characterization of O-carboxymethyl chitosan-sodium alginate polyelectrolyte complexes

O-carboxymethyl chitosan (O-CMC) is a water-soluble derivative of chitosan. In this work, the formation of polyelectrolyte complex (PEC) between O-CMC and sodium alginate (SAL) was explored by investigating the effects of medium pH, polyelectrolytes mixing ratio, and ionic strength on the yield of O-CMC-SAL PECs. Meanwhile, the rheological, thermal, and microstructural properties of the PECs prepared at various medium acidities were characterized as well. The results indicated that the strongest complexation between O-CMC and SAL occurred in medium pH 6.5 and biopolymer ratio (R (O-CMC/SAL)) 1.5:1 (w/w) in the absence of added NaCl. Fourier transform infrared (FTIR) spectroscopy analysis revealed that both electrostatic interaction and hydrogen bonding were involved in PEC formation. The PECs possessed the porous structure and displayed predominately the elastic property with the highest moduli values being recorded at medium pH 3.5. It was concluded that the O-CMC-SAL PECs have potential biomedical applications due to the nearly neutral complexation pH and the porous structure for drug inclusion.