Solvent-Dependent Mn Doping: Profound Effects on Microstructure and Enhanced Photothermal/Photodynamic Performance in W18O49 Diversified System

Abstract

The development of efficient photothermal therapy (PTT) and photodynamic therapy (PDT) agents is crucial for overcoming the limitations of traditional cancer treatments, such as the need for single wavelength and the limited penetration depth of excitation light. The tumor microenvironment (TME), characterized by low oxygen levels and an overabundance of endogenous hydrogen peroxide (H2O2), further complicates the therapeutic efficacy. In this study, we synthesized a series of Mn-doped W18O49 materials using a one-step solvothermal method, systematically varying the solvents with n-propanol and isopropanol and manganese doping levels. The effects of solvent type and doping amount on crystal structures, morphology and photo conversion performance were investigated in detail. Under single-wavelength near-infrared (NIR) irradiation at 808/1064 nm, the synthesized materials demonstrated simultaneous hyperthermia and singlet oxygen (1O2) generation, enabling both PTT and PDT. Notably, the Mn-doped W18O49 materials accumulated in the TME could catalyze the conversion of H2O2 into O2, thereby enhancing the production of 1O2 and resulting in a self-amplifying therapeutic effect. This synergistic enhancement of PTT and PDT was further corroborated by in vitro studies, which showed significant inhibitory effects on cancer cell proliferation. Our findings demonstrate that solvent-dependent Mn doping profoundly affects the microstructure and phototherapeutic performance of W18O49 materials, providing a novel strategy for developing advanced PTT/PDT agents activated by single NIR irradiation and responsive to the TME.