pH-sensitive KHA/CMC-Fe3+@CS hydrogel loading and the drug release properties of riboflavin

To improve drug utilization, reduce the drug administration frequency, increase the release time, and reduce the drug side effects in the human body, we prepared (KHA/CMC-Fe3+)@CS hydrogel spheres using green and natural potassium humate (KHA), carboxymethyl cellulose (CMC), and chitosan (CS) as raw materials and Fe3+ as a crosslinking agent, and loaded them with riboflavin for drug sustained-release study using the drop ball method. The tests with FTIR, SEM, TG, and X-ray diffractometer showed that the coordination among KHA, CMC, and Fe3+ formed a three-dimensional network structure, where CS was encapsulated on the surface of the hydrogel spheres via noncovalent bonding, resulting in good thermal stability. The stability, drug loading, swelling, and in vitro release of the (KHA/CMC-Fe3+)@CS hydrogel spheres were investigated. The results showed that the hydrogel spheres were significantly pH-sensitive, with 11.16 g/g higher swelling in an alkaline environment (pH = 7.4) than that in an acidic environment (pH = 1.2). The swelling and drug release process of the hydrogel spheres were analyzed using mathematical models, concluding that the hydrogel swelling follows Schott second-order swelling kinetics, and the drug release mechanism was Fickian delivery mode.