Multifunctional polyphenol-coated Fe3O4@Pt nanocomposites for in vitro NIR-induced cancer chemodynamic and photothermal therapy.

Synergistic chemodynamic and photothermal therapies hold great promise for enhancing the efficacy of cancer treatment. Herein, we report polyphenol-coated Fe3O4@Pt magnetic nanocomposites based on four shell chemistries (polydopamine (PDA); polylevodopa P(L-DOPA); polygallic acid (PGA), and polypyrogallol (PPGL)) prepared under mildly acidic and basic polymerisation conditions, yielding core-shell structures with pH- and monomer-dependent shell thickness. All examined nanocomposites remained superparamagnetic at 300 K and exhibited enhanced visible-NIR absorbance and stable heating under repeated 808 nm irradiation, with pH 9.5-synthesised coatings generally outperforming those obtained at pH 5.8, and PDA or P(L-DOPA) showing stronger photothermal effect than PGA and PPGL. Photothermal conversion efficiencies increased from 3.3% for Fe3O4@Pt to 11.82% for Fe3O4@Pt@PDA and 11.66% for Fe3O4@Pt@P(L-DOPA). Notably, Fe3O4@Pt@P(L-DOPA) showed the highest peroxidase-like activity among tested nanoparticles, while Fe3O4@Pt@PDA and Fe3O4@Pt@P(L-DOPA) depleted GSH under physiological-like and tumour-mimicking conditions in vitro. The cytotoxicity of the nanocomposites was evaluated using the MTT and alamarBlue assay with the HaCaT and A375 cell lines, confirming the low toxicity of Fe3O4@Pt@PDA and Fe3O4@Pt@P(L-DOPA). Both nanocomposites effectively reduced cancer cell viability under NIR irradiation, demonstrating their potential as photothermal agents. The unique properties of these multifunctional nanocomposites surpass those of Fe3O4@Pt, highlighting their promise for combined photothermal and chemodynamic cancer therapy.