Long-Term Stable\nEu<sub>2</sub>O<sub>3</sub>‑Loaded\nDendritic Mesoporous Silica Nanoprobes with Coordination-Enhanced\nPhotoluminescence for Ultrasensitive Lateral Flow Immunoassay

Inorganic lanthanide nanomaterials as photoluminescent\nbiolabels\nhave attracted increasing attention due to their superior physicochemical\nproperties. However, unstable conjugation of inorganic lanthanide\nnanomaterials with biological function units (such as antibodies)\ninduces instability of conjugated complexes in aqueous solution, limiting\ntheir clinical application. In this study, we developed a rapid point-of-care\ntesting (POCT) platform strategy based on coordination-enhanced time-resolved\nluminescence of specially nanostructural lanthanide particles for\nlateral flow immunoassay (CE-TRFIA). This strategy integrates a nanoprobe\nvia a dendritic mesoporous silica nanosphere (DMSN) loading a large\namount of ultrasmall amorphous europium oxide (Eu<sub>2</sub>O<sub>3</sub>) nanoparticles, which rapidly dissolve to release Eu<sup>3+</sup> cations under neutral pH value and form luminescent complexes\nwith photosensitizers (such as β-NTA and TOPO) in an LFIA system.\nThis innovative strategy achieves high-sensitivity detection and long-term\nstability primarily through high-loading probes, excellent dissolution\nenhancement, stable covalent coupling, and time-resolved detection.\nWith Procalcitonin (PCT) antigen selected as the detection sample,\nthis approach achieves high-sensitivity detection of PCT with a limit\nof detection (LoD) as low as 1.9 pg/mL, significantly lower than that\nof commercial LFIA (0.1 ng/mL), and excellent clinical correlation\n(<i>r</i> = 0.989). The method offers chemiluminescence-level\nsensitivity without the need for large instruments while retaining\nthe real-time detection characteristics of LFIA. Our results highlight\nCE-TRFIA as a highly sensitive, specific, and rapid POCT solution\nfor detecting low-abundance biomarkers such as PCT, enhancing the\ndiagnostic capabilities of traditional LFIA and offering significant\npotential for ultrasensitive and rapid clinical diagnostics.