Three-dimensional windmill-shaped CAuNP based on chirality transfer and size engineering for highly sensitive immunochromatography assay

Abstract

Chiral plasmonic nanomaterials with distinctive twisted morphologies exhibit unique local surface plasmon resonance (LSPR) capability and robust plasmonic optical activity, showing promise as activatable probes to enhance the sensitivity of lateral flow immunoassay (LFIA). Herein, utilizes L-glutathione (L-GSH) to induce an anisotropic structure, thereby aggrandizing the extinction cross section through the resultant asymmetric local charge distribution on the surface of chiral gold nanoparticles (CAuNPs). Based on chiral transfer and size engineering theories, precise control over the quantities of L-GSH and cubic AuNPs seed was employed to achieve rational modulation of deposition and diffusion rates, facilitating the controlled synthesis of large-sized CAuNPs with uniform morphology, high colorimetric performance, and further enhancement of LSPR frequency. The distinctive pinwheel-shaped CAuNPs exhibits a brown-black color and broadband absorption in the range of 300–900 nm. Using this newly synthesized CAuNPs, a novel LFIA for the detection of Salmonella Typhimurium was developed. The limit of detection reached 0.59 × 10² CFU/mL, which is lower than the LFIA based on traditional nanomaterials for detecting S. Typhimurium, with a reaction time of 20 min, robustly showcasing the efficacy of CAuNPs in enabling precise point-of-care testing.