Red Zn2SiO4:Eu3+ and Mg2TiO4:Mn4+ nanophosphors for on-site rapid optical detections: Synthesis and characterization.

ABSTRACT

This study reports the synthesis and characterization of the red nanophosphors Zn2SiO4Eu3+ (ZSOEu3+) and Mg2TiO4Mn4+ (MTOMn4+). The use of phosphors as a fluorescence label for lateral flow immunochromatographic assay (LFIA) has also been described. The optimal photoluminescence (PL) for ZSOEu3+ was obtained when it was synthesized with 7 mol% of Eu3+ 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 ZSOEu3+. MTOMn4+ 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 ZSOEu3+- and MTOMn4+-labeled LFIA, respectively. Thus, the ZSOEu3+ and MTOMn4+ nanophosphors are capable of human IgG recognition and are the promising candidates as fluorescent labels for on-site rapid optical biodetection. SUPPLEMENTARY INFORMATION The online version contains supplementary material available at 10.1007/s00339-021-04733-0.