Lanthanide-doped fluoride core@dual-shells nanoparticles for multi-mode temperature and molecular sensing

• • Maximum relative temperature sensitivity of 2.27%/K, derived from three independent intensity ratios (I520/I550, I697/I650, I697/I475), enables multi-mode thermometry with reduced measurement uncertainty; this exceeds typical single-mode Er3+ or Tm3+ systems, offering a route to reliable thermal readout in microelectronics and biomedical probes. • • Limits of detection for methyl orange and rhodamine B are 0.48 and 0.57 μg/mL, respectively, under dual 980/808 nm excitation; these values are lower than most lanthanide-doped UC systems, supporting trace-level pollutant monitoring in aquatic environments without preconcentration. • • Core@shell@shell architecture (NaNd0.7Gd0.3F4:Yb@NaYF4:Yb/Er@NaGdF4:Yb/Tm) spatially isolates Er3+ and Tm3+ activators, suppressing cross-relaxation and enabling orthogonal multi-channel emission; this design allows simultaneous temperature and molecular sensing from a single nanoparticle, reducing hardware complexity in multiplexed assays. • • Dual-wavelength excitation (980 and 808 nm) provides independent control over Er3+ and Tm3+ emission channels, facilitating multi-channel molecular detection without spectral crosstalk; this operational flexibility is critical for field-deployable sensors where excitation source selection must balance penetration depth and photothermal load.