Near infrared lanthanide-doped nanoparticles for low interference lateral flow immunoassay test.

Lateral flow immunoassay test (LFT), as a method of point of care test, is widely used in disease diagnosis, food security and environment observation, due to its portability and rapidity. Fluorescence lateral flow immunoassay was developed recently to enhance the sensitivity and accuracy. However, for most fluorescence reporters, their emission and excitation wavelength are located at the ultraviolet or visible region. Serum or whole blood absorb and scatter light of this region severely and these will result in background signal interference. In this study, we replace traditional fluorescence reporters with near-infrared lanthanide-doped nanoparticles (NIR-RENPs) to establish NIR LFT platform. Blood and other biological samples scatter and absorb less near-infrared light than visible light, and the autofluorescence of biological samples is rarely located in this region. Therefore, using NIR light as signal can diminish the interference of background noise and suffer from less signal attenuation. Besides, compared with commonly-used NIR organic dye, NIR-RENPs has better stability. It is promising that lateral flow immunoassay based on NIR lanthanide-doped nanoparticles is able to acquire lower detection limit and better accuracy, and more suitable for commercial application.