Functional integration and synergistic effects of metal-based nanocomplexes in tumor photothermal therapy and bioimaging.

Photothermal therapy (PTT), as an important tumor treatment method in the biomedical field, offers advantages such as non-invasiveness, high selectivity, and low toxicity and side effects. Metal-based nanocomplexes exhibit immense potential in PTT due to their high photothermal conversion efficiency, tunable surface structures, and unique physicochemical properties. They can also serve as contrast agents for bioimaging, enabling integrated tumor diagnosis and treatment. This paper systematically reviews the latest research advancements of inorganic metal-based nanocomplexes in bioimaging and PTT, focusing on their construction strategies and application advantages as multifunctional diagnostic and therapeutic platforms. In bioimaging, metal-based nanomaterials achieve precise diagnosis through computerized tomography (CT), photoacoustic imaging (PAI), magnetic resonance imaging (MRI), and multimodal imaging by leveraging their properties such as X-ray attenuation, surface plasmon resonance, and superparamagnetism. Gold-based nanomaterials demonstrate superior contrast to traditional iodine agents in CT imaging, while iron oxide nanoparticles, as MRI contrast agents, combine biocompatibility with magnetic targeting capabilities. In the field of PTT, gold-based nanomaterials act as efficient photothermal conversion agents due to their localized surface plasmon resonance effect and modifiability. Bismuth-based materials show potential as alternatives owing to their low cost and high photothermal efficiency, while transition metal-based materials such as titanium, copper, and molybdenum achieve synergistic photothermal-chemodynamic therapy through unique band structures and Fenton-like reactions. To address challenges in clinical translation, this paper proposes strategies such as enhancing targeting through ligand modification, achieving low-temperature therapy by inhibiting heat shock proteins, and combining chemotherapy/immunotherapy to overcome issues such as thermal damage and insufficient penetration depth. Particular emphasis is placed on the innovative design of bimetallic nanomaterials that improve photothermal performance through high-entropy effects and synergistic catalytic actions. This paper aims to provide theoretical guidance for the development of metal-based nanodiagnostic and therapeutic platforms that integrate diagnostic monitoring and precise treatment, thereby promoting the advancement of integrated tumor diagnosis and therapy.