Fabrication of pH-sensitive double cross-linked sodium alginate/chitosan hydrogels for controlled release of amoxicillin

This research aims to fabricate a potent pH-sensitive double network sodium alginate/chitosan hydrogel cross-linked by calcium chloride (CaCl2) and glutaraldehyde for the controlled release of amoxicillin (AMX) to mitigate gastrointestinal tract bacterial infection. The effect of polymer ratios and CaCl2 concentration is investigated by the developing porosity, gel fraction, and swelling ratios in simulated physiological fluids of different pH and in vitro biodegradation at pH 7.4. Interaction between the polymers with the formation of cross-linked structures, amorphous phase nature, good thermal stability, and transition from porous, fibrous structures to highly densified structures of the hydrogels is revealed by scanning electron microscopy, Fourier-transform infrared spectroscopy, x-ray diffraction, and thermogravimetric analysis. Based on structure-property relationships, a sodium alginate/chitosan hydrogel (weight ratio 75:25) cross-linked with 2% CaCl2 and soaked in 2% (25 wt/v% solutions) glutaraldehyde is chosen for the incorporation of 200 mg of the drug. The percent cumulative AMX release in physiological fluids and the drug release kinetics using different models reveal that the most appropriate Korsmeyer-Peppas model suggests AMX release from the matrix follows diffusion coupled with swelling-regulated time-dependent non-Fickian transport process related to hydrogel erosion. Excellent antibacterial against Streptococcus pyogenes and Escherichia coli is exhibited by this composition.