Doping Engineering To Modulate Surface Plasmon Resonance and Enzyme-like Activities for Enhancing Photoacoustic Imaging-Guided Targeted Cancer Therapy in the Second Near-Infrared Window

Biological imaging-guided targeted tumor therapy has been a soughtafter goal in the field of cancer diagnosis and treatment. To this end, we proposed a strategy to modulate surface plasmon resonance and endow WO3-x nanoparticles (NPs) with enzyme-like catalytic properties by doping Fe2+ in the structure of the NPs. Doping of the Fe2+ introduced oxygen vacancies into the structure of the NPs, inducing a red shift of the maximum absorption wavelength into the near-infrared II (NIR-II) region and enhancing the photoacoustic (PA) and photothermal properties of the NPs for more effective imaging-guided cancer therapy. Under NIR-II laser irradiation, the Fe-WO3-x NPs produced very strong NIR-II PA and photothermal effects, which significantly enhanced the PA imaging and photothermal treatment effects. On the other hand, Fe2+ in Fe-WO3-x could undergo Fenton reactions with H2O2 in the tumor tissue to generate <middle dot>OH for chemodynamic therapy. In addition, Fe-WO3-x can also catalyze the above reactions to produce more reactive oxygen species (ROS) and induce the oxidation of NADH to interfere with intracellular adenosine triphosphate (ATP) synthesis, thereby further improving the efficiency of cancer therapy. Specific imaging of tumor tissue and targeted synergistic therapy was achieved after ligation of a MUC1 aptamer to the surface of the Fe-WO3-x NPs by the complexing of -COOH in MUC1 with tungsten ions on the surface of the NPs. These results demonstrated that Fe-WO3-x NPs could be a promising diagnosis and therapeutic agent for cancer. Such a study opens up new avenues into the rational design of nanodiagnosis and treatment agents for NIR-II PA imaging and cancer therapy.