Red Zn_2SiO_4:Eu~(3+) and Mg_2TiO_4:Mn~(4+) nanophosphors for on-site rapid optical detections: Synthesis and characterization

摘要

This study reports the synthesis and characterization of the red nanophosphors Zn_2SiO_4:Eu~(3+) (ZSO:Eu~(3+)) and Mg_2TiO_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 E_a (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.