Noninvasive temperature monitoring for dual-modal tumor therapy based on lanthanide-doped up-conversion nanocomposites

Accurate treatment of photothermal therapy (PTT) is crucial to avoid the unnecessary injury of normal cells and tissues. Therefore the real-time temperature monitoring in the PTT process has drawn more and more attention in recent years. Herein, we designed and prepared one kind of lanthanide (Ln³⁺)-doped up-conversion nanocomposites with multi-functions, which can not only provide temperature feedback in PTT process, but also play the photodynamic therapy (PDT) function for the synergistic effect of tumor therapy. Based on NaYF₄:Yb, Er up-conversion nanoparticles (UCNPs), mesoporous SiO₂ was modified on the surface combined with photosensitizer Chlorin e6 (Ce6) molecules, which could be excited by red emission of Er³⁺ under the 980 nm laser. Cit-CuS NPs were further linked on the surface of the composite served as photothermal conversion agent, therefore, the temperature of the PTT site can be monitored by recording the ratio of I₅₂₅/I₅₄₅ of green emissions, especially within the physiological range. Based on the guidance obtained from spectral experiments, we further investigated the dual-modal therapy effect both in vitro and in vivo, respectively, and acquired decent results.