Preparation and characterization of chitosan-coated calcium alginate film

Abstract

The effects of cross-linking with calcium ion and chitosan coating on mechanical properties, swelling behavior and drug release characteristics of alginate films were studied. FTIR spectra of chitosan-coated calcium alginate films showed the characteristic peaks of chitosan indicating that chitosan was successfully coated on calcium alginate film. The chitosan coating on calcium alginate film was also confirmed by ninhydrin staining. Chitosan-coated calcium alginate films showed better tensile strength and Young's modulus than alginate and noncoated calsium alginate films due to the electrostatic interaction at the interface between alginate and chitosan. Both noncated calcium alginate and chitosan-coated calcium alginate films possessed pH-sensitive swelling characteristics and chitosan-coated clacium alginate films showed higher degrees of swelling then thd noncoated films. Drug release studies of the films were carried out at 37 C at simulated physiological pHs, i.e. pH 2, pH 5.5 and pH 7.2, using salicylic acid and theophylline as model drugs. The amounts of model drugs released from chitosan-coated calcium alginate films were lower than from the noncoated films and drug release at pH 5.5 gave higher equilibrium drug releasing amounts than at pH 2.0 for both model drugs.