A novel core–shell–shell SiO2@CePO4:Tb@SiO2 submicro-sphere was controllably synthesized by a bridging ligand organosilane HOOCC6H4N(CONH(CH2)3Si(OCH2CH3)3)2 (MABA-Si) connecting the silica core and rare earth ions. The as-synthesized samples were investigated using scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy-dispersive X-ray spectroscopy (EDX), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and infrared spectroscopy (IR). It is found that SiO2@CePO4:Tb@SiO2 has a ∼25 nm outermost shell, a ∼4 nm intermediate shell, and a ∼200 nm core. SiO2@CePO4:Tb@SiO2 exhibits stable photoluminescence properties in aqueous solution: its photoluminescence intensity was unquenched even after 15 days. The core–shell–shell submicro-spheres were found to have better photoluminescence than the core–shell submicro-spheres because the SiO2 shell protected the phosphor materials and then improved its photoluminescence intensity and biocompatibility. A formation mechanism of the core–shell–shell SiO2@CePO4:Tb@SiO2 submicro-spheres was proposed. Thus, the low-cost preparation of the core–shell–shell SiO2@CePO4:Tb@SiO2 submicro-spheres could be rationally achieved using SiO2.
Core-shell-shell SiO 2 @LaVO 4 :RE@SiO 2 -MABA-Si microspheres enable dual-probe Hg 2+ /Cu 2+ detection. • Detection limits of 0.14 µM for Hg²⁺ and 92.96 nM for Cu 2+ with 8–20 min response time. • IFE coupled with coordination governs selective quenching of Eu 3+ (616 nm) and Tb 3+ (543 nm) emission. • Robust performance across pH 3.0–12, 7 days stability, and 98–103.83% real-water recoveries. A dual-channel sensing system based on core-shell-shell SiO 2 @LaVO 4 :RE@SiO 2 -MABA-Si (RE = Eu, Tb) microspheres was developed for the selective detection of Hg 2+ and Cu 2+ in aqueous media. The microspheres were synthesized by grafting MABA-Si onto SiO 2 @LaVO 4 :RE@SiO 2 , yielding a triple-layered architecture (~105 nm SiO 2 core, ~4 nm LaVO 4 :RE luminescent shell, ~14 nm SiO 2 -MABA-Si functional shell). Sensing relies on the inner filter effect (IFE) coupled with synergistic coordination: MABA-Si captures Hg 2+ or Cu 2+ , and the resulting metal-ligand complexes quench the Eu 3+ (616 nm) or Tb 3+ (543 nm) emission, respectively. The Tb 3+ -based probe detected Cu 2+ with a limit of 92.96 nM and an 8 min response, while the Eu 3+ -based probe detected Hg 2+ with a limit of 0.14 μM and a 20 min response. The Hg 2+ system showed reversible "on-off-on" switching with L -cysteine. The SiO 2 shell maintained stable luminescence over pH 3.0 −12 and 7 days storage. Real water tests gave recoveries of 99 −103.83% (Hg 2+ ) and 98 −102.50% (Cu 2+ ) with RSDs below 2.4%. This platform offers a practical approach for dual-ion heavy metal monitoring. Download: Download high-res image (253KB) Download: Download full-size image
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