Near-infrared responsive Au–Mn–HAp nanocomposite for fluorescence imaging and combined phototherapy for breast cancer

This study investigated a microwave-assisted synthesis method for the rapid deposition of gold (Au) nanoparticles (NPs) doped with manganese (Mn) onto the surface of hydroxyapatite (HAp). HAp NPs were first synthesized using a wet precipitation method, followed by Au loading and Mn doping to achieve a synergistic imaging-guided photothermal/photodynamic effect in breast cancer treatment. The substitution of Ca²⁺ ions with smaller Mn²⁺ ions enhanced the formation of Mn-HAp, which served as a nano-carrier with a large surface area, enabling conjugation of folic acid (FA) and indocyanine green (ICG) fluorescent dye without any toxicity. This innovative approach considerably enhanced the efficacy of photodynamic therapy (PDT) by generating reactive oxygen species (ROS) to eliminate cancer cells. The Au-Mn-HAp-FA-ICG nanocomposite showed promising contrast efficiency and enhanced PDT, acting as an effective photodynamic probe, as confirmed by DCFH-DA staining. <i>In vitro</i> experiments demonstrated the potent efficacy of Au NPs in combination with fluorescence-imaging-guided PDT treatment, achieving effective photothermal ablation of cancer cells after 5 min of laser irradiation. The biocompatibility of the synthesized NPs was assessed using an MTT assay and fluorescence staining, which revealed that the nanostructured materials could be ideal agents for imaging-guided cancer therapy.