NIR-II emitting rare-earth nanoparticles for a lateral flow immunoassay in hemolysis

Abstract Fluorescent lateral flow immunoassay (LFA) is a popular analytical tool used in point-of-care testing. However, hemolysis detection using LFA with visible fluorescent labels is still a big challenge due to the existence of autofluorescence interference, light absorption, and scattering in the visible region. Herein, an LFA platform using Yb, Er,Ce co-doped core-shell-shell-shell nanoparticles (Er, Ce-CSSS) with 1550 nm emission as fluorescent labels is established for hemolysis detection. Er, Ce-CSSS offer less luminescence attenuation and minimized autofluorescence interference than Yb, Tm co-doped core-shell nanoparticles with 800 nm emission in hemolytic samples. Moreover, Alpha-fetoprotein (AFP) is utilized as a model analyte to test the performance of Er, Ce-CSSS based LFA platform for hemolysis detection. The platform can reach a testing time of 10 min, a detection limit of 1.00 ng/mL, a recovery rate of 96.7 %–107.3 % and an inter-assay coefficient of variation of 3.6 %–4.9 % for AFP detection. In addition, it can only recognize AFP without cross-reactions with other analytes. Therefore, our study demonstrates that the second near-infrared window (NIR-II) emitting rare-earth nanoparticles are promising fluorescent labels in LFA for rapid biomarkers detection with good sensitivity, precision, and specificity in hemolysis.