Engineered collaborative grown model regulation and LSPR-tunable of Pd@Au core-shell nanoparticles for highly...

Lateral flow immunoassay (LFIA) based on fluorescence quenching is a novel approach to improve the detection sensitivity in recent years. However, inefficient fluorescence quenchers and unclear fluorescence quenching mechanisms have limited the development of fluorescence quenching lateral flow immunoassay (FQ-LFIA). Herein, we synthesized Pd@Au core-shell nanostar (Pd@Au NSs) and Pd@Au core-shell icosahedra nanoparticles (Pd@Au IHNPs) with excellent fluorescence-quenching ability and localized surface plasmon resonance (LSPR) tunable performance by adjusting the injection rate of Au(III) precursors. The absorption peaks of Pd@Au NSs and Pd@Au IHNPs were highly coincident with the emission peaks of the red and green quantum dot nanobeads (QBs), respectively. The fluorescence of green QBs and red QBs was absorbed by the Pd@Au NSs and Pd@Au IHNPs in the inner-filter effect (IFE) approach, which achieved efficient fluorescence quenching (kn_{(Pd@Au NSs)} = 3.41 and kn_{(Pd@Au IHNPs)} = 3.68). Based on Pd@Au NSs and Pd@Au IHNPs as efficient quenchers, the highly sensitive FQ-LFIA was established. The Limits of detection (LODs) of Pd@Au NSs-FQ-LFIA and Pd@Au IHNPs-FQ-LFIA were 0.051 and 0.012 ng mL^-1, respectively. Furthermore, the method demonstrated satisfactory recoveries (89.68-117.20 %) for the detection of ABZ in food samples.