A dual-antibody sandwich immunoassay using upconversion nanoparticles and magnetic beads for fibrinogen detection.

Fibrinogen is a vital biomarker for coagulation disorders, with reduced levels increasing bleeding risk and mortality, requiring rapid detection for early diagnosis. Enzyme-linked immunosorbent assay (ELISA) is commonly employed in clinical environments; however, its prolonged processing duration and insufficient sensitivity hinder its utility for swift diagnostics. We addressed these limitations by creating a dual-antibody sandwich immunoassay that employs upconversion nanoparticles (UCNPs) and magnetic beads (MBs) for the precise and sensitive detection of fibrinogen. The enhanced analytical performance of the method is attributed to the use of UCNPs and MBs. UCNPs enhance the signal-to-noise ratio by emitting visible light under near-infrared excitation, which reduces background interference from autofluorescence and light scattering in biological samples. Meanwhile, MBs facilitate specific enrichment of fibrinogen by selectively capturing the target analyte, enabling efficient isolation from complex sample matrices. This synergy improves sensitivity and specificity, achieving a 2 ng/mL detection limit with a 15-fold sensitivity increase, simpler operation, and shorter detection time compared to conventional ELISA kits. This platform offers a robust solution for fibrinogen detection, with potential for broad application in clinical diagnostics.