Preparation of polyelectrolyte complex gel of sodium alginate with chitosan using basic solution of chitosan.

In general, chitosan (CS) cannot be dissolved in basic solution, however it was found that the basic CS solution could be prepared using sodium hydrogen carbonate. NMR measurements revealed that CS was transformed to carbamate ion in the basic condition (around pH 8) thus it acts as anionic nature in this medium. Based on this discovery, novel polyelectrolyte complex (PEC) gel of sodium alginate (SA) and CS was successfully prepared using a basic CS solution and d-gluconolactone (GDL). Gel formation mechanism was explained based on the 1H and 13C NMR measurement results. It was found that the elastic modulus of SA/CS PEC gel were higher than that of SA/Chitosan oligomer gel. Moreover, the SA/CS PEC gel was the homogeneous gel and become over 7000 Pa for maximum of elastic modulus. This novel PEC gel will be used in several applications such as tissue engineering, drug delivery system and fuel cell.