A NIR-controlled cage mimicking system for hydrophobic drug mediated cancer therapy.

Most chemotherapeutic drugs commonly suffer from several shortcomings, including the lack of aqueous solubility, limited stability and adverse side effects. Although caging strategy has recently been employed as an effective approach to conceal and stabilize these drugs to achieve light-activated cancer therapy, it is plagued by the sophisticated drug modification process and deleterious solvent usage. In addition, using UV or Visible light to remove photocaged group is restricted to its limited tissue penetration ability in and phototoxicity. In this paper, by anchoring photochromic spiropyran on the mesoporous silica coated upconversion nanoparticles (UCNP-SP), we design a NIR-controlled cage mimicking system. Our results indicate that hydrophobic drug can be concealed inside the channels of the nanocarrier with high stability and "uncaged" via NIR irradiation-triggered hydrophobicity-hydrophilicity switch of the spiropyran molecules, finally inducing drug release and recovering their bioactivity. Moreover, under NIR illumination, the UV/Visible emissions from UCNP can also efficaciously initiate the generation of reactive oxygen species (ROS) by Curcumin, further improving the therapeutic efficiency. Both in vitro and in vivo experimental results validate that NIR irradiated nanosystem can produce remarkably enhanced antitumor efficiency.