NIR-II fluorescence lateral flow immunosensor based on efficient energy transfer probe for point-of-care testing of tumor biomarkers

Fluorescence lateral flow immunoassay (LFA) has emerged as a powerful tool for rapid screening of various biomarkers owing to its simplicity, sensitivity and flexibility. It is noteworthy that fluorescent probe mainly determines the analytical performance of LFA. Due to the emission and excitation wavelengths are located in the visible region, most fluorophores are inevitably subject to light scattering and background autofluorescence. Herein, we reported a novel LFA sensor based on the second near-infrared (NIR-II) fluorescent probe with excellent anti-interference capability. The designed NIR-II probe was the Nd3+ and Yb3+ doped rare earth nanoparticles (RENPs) by employing Nd3+ as energy donor and Yb3+ as energy acceptor, which of the donor-acceptor energy transfer (ET) efficiency reached up to 80.7%. Meanwhile, relying on the convenient and effective encapsulation strategy of poly (lactic-co-glycolic acid) (PLGA) microspheres to RENPs, the surface functionalized NIR-II probe (RE@PLGA) was obtained for subsequent bioconjugation. Benefiting from the optical advantages of NIR-II probe, this proposed NIR-II LFA displayed a good linear relationship ranging from 7 ng/mL to 200 ng/mL for the detection of α-fetoprotein (AFP), an important biomarker of hepatocellular carcinoma (HCC). The limit of detection (LOD) was determined as low as 3.0 ng/mL, which was of 8.3 times lower than clinical cutoff value. It is promising that LFA sensor based on this efficient RENPs probe provides new opportunities for high sensitive detection of various biomarkers in biological samples.