Layer-by-layer assembled hyaluronic acid/chitosan-coated Fe₃O₄@rGO nanoparticles: Synthesis and characterization for doxorubicin delivery in breast cancer cells

Magnetic nanoparticles (MNPs) are of significant interest for biomedical applications. Among them, Fe3O4 nanoparticles are widely used. However, they suffer from oxidation and reduced magnetization under physiological conditions. To overcome this limitation, Fe3O4@rGO (FR) nanoparticles were synthesized via a solvothermal method and optimized for 20 h reaction time. For further functionalization, the MNPs were coated with a multilayered polymeric shell consisting of alternating hyaluronic acid (HA) and chitosan (CHI) layers through a Layer-by-Layer (LbL) assembly method, with doxorubicin (DOX) embedded directly within the HA layers for controlled release, and referred to as FR-HC@DOX. In this design, rGO enhances structural stability, HA provides CD44-mediated targeting ability, and CHI improves biocompatibility. The LbL technique allows for precise control of coating thickness and uniform layer deposition, enhancing drug-loading efficiency and ensuring controllable release profiles. The optimized FR-HC@DOX maintained sufficient magnetic response (M-s = 26.04 emu/g) after drug loading, which is substantially higher than most reported polymer-coated Fe3O4 systems that typically drop below 20 emu/g. These magnetic nanocarriers also exhibited strong pH sensitivity (similar to 100 % release at pH 5.5 vs 13 % at pH 7.4) and showed potent anticancer activity in MCF-7 cells while remaining biocompatible in MCF-12A healthy control cells at concentrations up to 80 mu g/mL. This study presents a new approach by combining rGO embedded/coated Fe3O4 with multilayer HA/CHI coatings, creating a magnetic nanocarrier that improves the stability of Fe3O4, is controllable, pH-responsive, and targeted drug release. These results position the system as a distinctive and effective nanoplatform for magnetically guided, tumor-targeted chemotherapy.