Development of carboxymethyl chitosan hydrogel beads in alcohol-aqueous binary solvent for nutrient delivery applications

Carboxymethyl chitosan (CMCS) hydrogel beads were normally prepared from a composite formulation with other polymers, such as alginate. In present study, a novel method was developed to prepare CMCS hydrogel beads in alcohol-aqueous binary solvents. The morphology and shape of the beads were highly dependent on alcohol concentration. The most spherical hydrogel beads were obtained with 3% calcium and 30% alcohol concentration. The chemical crosslinking agent, glutaraldehyde, was needed to maintain the hydrogel integrity and morphology upon drying. Vitamin D3, a model nutrient, was encapsulated into the beads and 96.9% encapsulation efficiency was obtained. The effects of freeze-drying and room temperature drying were studied on the swelling behaviors and release properties in simulated gastrointestinal conditions. Possible mechanisms for CMCS hydrogel beads formation in binary solvents were discussed. The CMCS hydrogel beads prepared in 30% alcohol-aqueous binary solvent may be a promising delivery system for hydrophobic nutrients or drugs.