Manipulating Near-Infrared Absorption via Engineering Anisotropic Plasmonic Spiky Au Nanocubes for the Highly Efficient Dual-Response Immune Detection of T-2 Toxin

Integrating specific immune recognition, a desirable extinction coefficient, and conspicuous photothermal conversion ability into a single-immune probe to enhance the analysis performance represents an appealing yet significantly challenging task. Herein, by delicately manipulating the geometry of plasmonic nanoparticles from spherical to spiky, precise engineering approach-based spiky Au nanocubes (S-AuNCs) are employed to address this challenge, which fully exploits the plasmon resonance absorption-induced photothermal effect. The finite difference time domain (FDTD) method was employed to computationally simulate the electromagnetic and thermal fields while assessing the feasibility of regulating plasmon resonance for enhanced photothermal absorption. The optimized noble photothermal agent simultaneously exhibits acceptable near-infrared absorption (NIR), a significantly increased 808 nm extinction coefficient (145 times higher than that of AuNPs), favorable antibody coupling ability, and desirable photothermal conversion behavior. Consequently, the satisfactory performance of the S-AuNCs-guided colorimetric and photothermal lateral flow immunoassay (CPLFIA) is demonstrated for the sensitive detection of T-2 toxin. In comparison to spherical AuNPs (35.2 pg/mL), the dual-mode detection sensitivity was enhanced by 1.862-fold and 5.18-fold, respectively, achieving limits of detection at 18.9 pg/mL (colorimetric mode) and 6.8 pg/mL (photothermal mode). Therefore, S-AuNCs-guided CPLFIA holds great potential in advancing food mycotoxin safety control.