NIR-II emissive lateral flow immunoassay for accurate determination of tumor marker in hemolysis

Fluorescent lateral flow immunoassay (LFIA) is one of the most popular strategies for point-of-care testing (POCT), which is capable of rapid screening for disease detection. However, the existing fluorescent LFIA is inapplicable to the hemolytic sample, whose strong absorbance, scattering and autofluorescence in visible region will interfere with the fluorescent signal. To address this issue, we developed a NIR-II LFIA detection platform (termed as NIR-II-LFIA platform) by integrating a portable NIR-II reader and a NIR-II nanoprobes into LFIA. Due to the minimized interaction of NIR-II light with hemolytic sample, this NIR-II LFIA can significantly eliminate the interference of absorbance, scattering and autofluorescence. We further applied this LFIA planform to alpha-fetoprotein (AFP) detection in hemolytic blood sample with high-accuracy and -sensitivity. This strategy exhibits a wide dynamic range of detection by 3 orders of magnitude from 0.80 to 5700 ng/mL. And the detection limit could be as low as 0.24 ng/mL, which is of 100 times lower than the clinical cutoff values (25 ng/mL). Therefore, we believe that this NIR-II-LFIA system can serve as a screening platform for early disease detection, especially in complex matrix samples with severe background interference.