Tumor-Specific NIR-Activatable Nanoreactor for Self-Enhanced Multimodal Imaging and Cancer Phototherapy

Responsive nanosystems for tumor treatment with high specificity and sensitivity have aroused great attention. Herein, we develop a tumor microenvironment responsive and near-infrared (NIR)-activatable theranostic nanoreactor for imaging-guided anticancer therapy. The nanoreactor (SnO_2-@AGP) is comprised of poly(vinylpyrrolidine) encapsulated hollow mesoporous black SnO_2- nanoparticles coloaded with glucose oxidase (GO) and 2,2'-azinobis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS). The constructed nanoreactor can be specifically activated through endogenous H₂O₂ by an NIR-mediated "bursting-like" process to enhance its imaging and therapeutic functions. Black SnO_2- with abundant oxygen vacancies expedites effective separation of electron-hole pairs from energy-band structure and endows them with strong hyperthermia effect upon NIR laser irradiation. The generating toxic H₂O₂ with the assistance of GO provides SnO_2-@AGP with the capacity of oxidative stress therapy. Ascended H₂O₂ can activate ABTS into ABTS^•+. ABTS^•+ not only possesses significant NIR absorption properties, but also disrupts intracellular glutathione to generate excessive reactive oxygen species for improved phototherapy, leading to more effective treatment together with oxidative stress therapy. Thus, SnO_2-@AGP with NIR-mediated and H₂O₂-activated performance presents tumor inhibition efficacy with minimized damage to normal tissues. These outstanding characteristics of SnO_2-@AGP bring an insight into the development of activatable nanoreactors for smart, precise, and non-invasive cancer theranostics.