Red Zn(2)SiO(4):Eu(3+) and Mg(2)TiO(4):Mn(4+) nanophosphors for on-site rapid optical detections: Synthesis and characterization

This study reports the synthesis and characterization of the red nanophosphors Zn(2)SiO(4):Eu(3+) (ZSO:Eu(3+)) and Mg(2)TiO(4):Mn(4+) (MTO:Mn(4+)). The use of phosphors as a fluorescence label for lateral flow immunochromatographic assay (LFIA) has also been described. The optimal photoluminescence (PL) for ZSO:Eu(3+) was obtained when it was synthesized with 7 mol% of Eu(3+) and annealed at 1100 °C for 1 h. Long fluorescence lifetime (1.01 ms), high activation energy [Formula: see text] (0.28 eV), and low PL degeneration (10% at 110 °C) are the characteristics of ZSO:Eu(3+). MTO:Mn(4+) also exhibited high PL intensity along with a high E(a) of 0.32 eV. The emission wavelengths of phosphors are biocompatible with the optical bio-window of tissues. When human immunoglobulin G (human IgG) at a constant concentration of 100 μg/mL was used for detection, the PL ratios of the test line to the control line were 2.15 and 2.28 for the ZSO:Eu(3+)- and MTO:Mn(4+)-labeled LFIA, respectively. Thus, the ZSO:Eu(3+) and MTO:Mn(4+) nanophosphors are capable of human IgG recognition and are the promising candidates as fluorescent labels for on-site rapid optical biodetection. GRAPHICAL ABSTRACT: [Image: see text] SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1007/s00339-021-04733-0.