Dextran-sodium alginate-modified nano-Fe₃O₄ hydrogel microspheres for pH and magnetic-responsive delivery of 5-fluorouracil.

Based on a deep-going comprehension of the molecular mechanisms that underlie tumor generation and transfer, modern medical science has obtained outstanding advances in the making of new medicine carrying systems for cancer therapy. In this study, we designed pH-responsive magnetic nanocomposite hydrogel microspheres with excellent biocompatibility for oral drug delivery. Dextran (DEX) and sodium alginate (SA) as the polymer matrix, and incorporated Fe₃O₄ nanoparticles (NPs) were used via one-pot synthesis. Subsequently, the anticancer drug 5-fluorouracil (5-FU) was successfully loaded into the DEX-SA-Fe₃O₄ system with a drug loading capacity of 22.16% and an encapsulation efficiency of 86.64%. In vitro release experiments have shown that the preparation can effectively retain the medicine under simulated gastric acid conditions (Cumulative release rate, 12.34%), while allowing continuous release in the alkaline environment of the intestines (Cumulative release rate, 84.77%). The release rate was consistent with the Korsmeyer-Peppas model, suggesting a combined mechanism of drug diffusion and polymer matrix relaxation. The MTT cytotoxicity assay showed that the blank DEX/SA/Fe₃O₄ microspheres exhibit high cell compatibility, but exhibit an obvious cytotoxic effect on HCT116 human colorectal cancer cells. Considering their pH-responsive behavior, controlled-release properties, and in vitro cytotoxicity, the magnetic nanocomposite hydrogel microspheres represent a promising platform for oral drug delivery in the treatment of colorectal cancer.