Lanthanide-Doped Nanoparticles Anchoring on Metal–Organic Frameworks with Thermally Enhanced Upconversion Luminescence for Sensitive Nanothermometers

Nanothermometers can detect changes in the local temperature in living cells and in vivo, revealing fundamental biological properties. Despite the exploration of different temperature-responsive materials, the design and development of temperature-sensing probes with high brightness and high sensitivity remain a daunting challenge. Here, we employed the UiO-66 type metal-organic frameworks (MOFs) to anchor UNCPs on the surface of the MOFs for constructing MOF@UCNPs nanohybrids. The in situ composite method with MOFs leads to the coordination interaction between the ligands and the surface of UCNPs, enabling controlled composite formation between different MOFs and UCNPs. Remarkably, the surface interaction favors the anomalous thermo-enhanced luminescence, achieving a 35-fold enhancement of UiO-66@NaYF₄:Yb/Tm at 413 K. Furthermore, these MOF@UCNPs nanohybrids with thermo-enhanced luminescence are developed as multifunctional biological probes for bioimaging and intracellular temperature sensing, demonstrating a high thermal sensitivity of 1.92% K^-1 in the physiological temperature range. Based on these findings, temperature monitoring of the local position was successfully carried out by the designed MOF@UCNPs nanoprobes in vivo. These findings underscore the potential of MOF@UCNPs nanohybrids, opening up new avenues for the development of a multifunctional platform for biological analysis.