Lateral flow immunoassay based on large-sized Au@Ag nanoparticles for stable colorimetric enhanced detection of...

The Lateral flow immunoassay (LFIA) has been widely used in environmental monitoring and disease diagnosis due to its advantages of low cost, simple operation, and convenience. However, its accuracy and sensitivity remain major challenges to be addressed. D-dimer is an important biomarker for thrombotic diseases. In this work, we show for the first time a core-shell Au@Ag nanoparticle (NP) labeled colorimetrically enhanced LFIA for D-dimer detection. The superior performance of Au@Ag LFIA stems from the silver shell's enhancement of plasmon resonance, which boosts optical signals to yield brighter scattering and superior visual contrast. Compared with conventional AuNPs, Au@AgNPs significantly improve sensitivity, leading to more accurate results. The detection limit for D-dimer was improved by approximately tenfold, reaching 1 ng/mL, due to the improved cross-coupling efficiency of Au@AgNPs compared with AuNPs. We anticipate that, with further development and validation, this enhanced LFIA could become a valuable tool in a wide range of clinical diagnostic applications.