Combination of two therapeutic strategies with different mechanisms can cooperatively prohibit cancer development.Photodynamic therapy(PDT)and gene therapy are two major modalities for the treatment of malignant tumors with different therapeutic mode.While they have distinctly different challenges to be addressed separately.The combination of photodynamic and gene therapy could overcome the disadvantages of individual therapy through different mechanisms of actions to achieve enhanced anti-cancer efficacy.Based on this principle,rare earth doped upconversion nanoparticles(UCNPs)encapsulated by cationic watersoluble conjugated polyelectrolyte brush(PFN+)were presented.Upon irradiation with a single NIR light,PFN+,as a photosensitizer,could generate cytotoxic single oxygen under 980 nm irradiation via luminescence resonance energy transfer.Concurrently,the light-switchable polymer sidechain could be cleaved by the upconverted UV light from cationic to zwitterionic and thus accelerate the intracellular release of siRNA.The combinational photodynamic and gene therapy facilitates increased therapeutic potency,and we anticipate that it may serve as a particular simple and useful platform for in vivo treatment of cancer from bench to beside.