Dual colorimetric-photothermal lateral flow immunoassay based on Au@Pt nanozymes for sensitive detection of cardiac troponin I.

A dual-signal lateral flow immunoassay (LFIA) was developed utilizing gold–platinum core–shell nanoparticles (Au@Pt NPs) for ultrasensitive cardiac troponin I (cTnI) detection. Owing to the synergistic electronic effects between the Au core and dendritic Pt shell, the Au@Pt NPs exhibit both high peroxidase-mimetic activity and a strong near-infrared photothermal effect. This allows for integrated colorimetric amplification and photothermal signal transduction within a single strip format. Under optimized conditions, the assay achieved a visual detection limit of 0.1 ng·mL⁻¹. Quantitative colorimetric determination yield limits of detection (LOD) of 0.044 ng·mL⁻¹ in PBS and 0.051 ng·mL⁻¹ in serum. Notably, the photothermal mode demonstrated exceptional matrix resilience, maintaining nearly identical LODs in PBS (0.036 ng·mL⁻¹) and serum (0.037 ng·mL⁻¹) over a linear range of 0.1–10 ng·mL⁻¹. This matrix-resilient performance is attributed to the thermophysical confinement effect of the biological matrix, which enhances the sensitivity slope in complex media. Overall, the proposed dual-mode LFIA provides a robust, pretreatment-free diagnostic tool that combines rapid visual screening with precise quantitative analysis, supporting early, point-of-care assessment of myocardial injury.