Lanthanide-doped fluoride core@dual-shells nanoparticles for multi-mode temperature and molecular sensing
Multimodal luminescent materials are of interest for multiplexed biosensing, multi-mode thermometry, and multidimensional displays, yet achieving simultaneous high-performance multimodal luminescence and multifunctionality remains challenging. This work reports NaNd0.7Gd0.3F4:Yb@NaYF4:Yb/Er@NaGdF4:Yb/Tm core@shell@shell upconversion nanoparticles (UCNPs) that enable multi-mode temperature and molecular sensing with enhanced sensitivity. By exploiting temperature-dependent intensity ratio variations of I520/I550, I697/I650, and I697/I475, multi-mode temperature sensing is achieved with a maximum relative sensitivity of 2.27%/K, exceeding many previously reported lanthanide-doped UC systems. The UCNPs are further applied for multi-channel molecular detection under both 980 and 808 nm excitation, with limits of detection for methyl orange (MO) and rhodamine B (RhB) as low as 0.48 and 0.57 μg/mL, respectively, outperforming most lanthanide-doped UC systems in the literature. These results underscore the potential of core@shell@shell UCNPs for advanced multimodal sensing in environmental monitoring, biomedical diagnostics, and multi-channel molecular analysis.