CuS as a gatekeeper of mesoporous upconversion nanoparticles-based drug controlled release system for tumor-targeted multimodal imaging and synergetic chemo-thermotherapy.

In this work, a tumor-targeted multifunctional mesoporous upconversion nanoparticle-based drug controlled release system was developed for UCL/MRI/PAT guided synergetic chemo-thermotherapy. Herein, the core-shell mesoporous upconversion nanoparticles served as drug carrier exhibiting higher upconversion luminescence emission intensity, with CuS as a gatekeeper through a cleavable disulfide bond under the influence of glutathione. CuS could not only prevent drug from early release during the delivery but also improve the delivery system function with the ability of photothermal therapy and photoacoustic tomography. Hyaluronic acid grafted on the surface of mesoporous upconversion nanoparticles could interact with CD44 receptors over-expressed in tumor cells, facilitating the drug delivery system to accumulate in tumor tissues. The synergy between chemotherapy and photothermal therapy was studied in vitro and in vivo, showing powerful anti-tumor effect. In cooperation with the multi-mode imaging, the size, site and morphology of tumor were clearly observed throughout the disease's progression.