Upconversion fluorescence-based PDT nanocomposites with self-oxygenation for malignant tumor therapy

Abstract

Photodynamic therapy (PDT) has made significant progress in tumor treatment, but it is still limited by poor light penetration and the imbalance between the hypoxic microenvironment of tumors and oxygen consumption during PDT, tremendously lowering the tumor removal efficiency. Herein, a high-efficiency PDT nano-system with high tissue penetration and oxygen-self-generation is presented for solving the hypoxic problem and enhancing the tumor therapeutic efficacy. By encapsulating chlorin e6 and upconversion nanoparticles (UCNPs) in an ultrathin silane (UCNPs-Ce6@Silane), an almost pure upconverted red light is obtained via NIR excitation and the red light further excites Ce6 molecules to exert PDT for effective tumor therapy. In this process, the NIR light could penetrate deeper into the tumor tissue, endowing this procedure with a better biological effect. In view of the tumor hypoxic microenvironment, a MnO₂ nanozyme was further modified on the surface of UCNPs-Ce6@Silane NPs, which could catalyze the excessive hydrogen peroxide in the tumor and provide sufficient oxygen for PDT. From the experiments in the cellular level and animal models, it could be proved that the brilliant composite nanoplatform could exhibit remarkable self-oxygenation properties, sufficient ROS production and distinguished tissue penetration. The prominent results indicated that this design would be a hopeful solution in the tumor therapeutics.