Lanthanide-Doped\nNanoparticles Anchoring on Metal–Organic\nFrameworks with Thermally Enhanced Upconversion Luminescence for Sensitive\nNanothermometers

Nanothermometers can detect changes in the local temperature\nin\nliving cells and in vivo, revealing fundamental biological properties.\nDespite the exploration of different temperature-responsive materials,\nthe design and development of temperature-sensing probes with high\nbrightness and high sensitivity remain a daunting challenge. Here,\nwe employed the UiO-66 type metal–organic frameworks (MOFs)\nto anchor UNCPs on the surface of the MOFs for constructing MOF@UCNPs\nnanohybrids. The in situ composite method with MOFs leads to the coordination\ninteraction between the ligands and the surface of UCNPs, enabling\ncontrolled composite formation between different MOFs and UCNPs. Remarkably,\nthe surface interaction favors the anomalous thermo-enhanced luminescence,\nachieving a 35-fold enhancement of UiO-66@NaYF<sub>4</sub>:Yb/Tm at\n413 K. Furthermore, these MOF@UCNPs nanohybrids with thermo-enhanced\nluminescence are developed as multifunctional biological probes for\nbioimaging and intracellular temperature sensing, demonstrating a\nhigh thermal sensitivity of 1.92% K<sup>–1</sup> in the physiological\ntemperature range. Based on these findings, temperature monitoring\nof the local position was successfully carried out by the designed\nMOF@UCNPs nanoprobes in vivo. These findings underscore the potential\nof MOF@UCNPs nanohybrids, opening up new avenues for the development\nof a multifunctional platform for biological analysis.