Au@PdPt nanoparticles-based colorimetric and photothermal dual-mode lateral flow immunoassay for the sensitive detection of ofloxacin.

Abstract

Ofloxacin (OFL) overuse leads to hazardous residues in food and the environment, necessitating sensitive and accurate detection. Traditional gold nanoparticle (AuNP)-based lateral flow immunoassays (LFIAs) suffer from low sensitivity, compromised accuracy, and reliance on single-mode signals, limiting their reliability. We synthesized Au@PdPt nanoparticles (NPs) via a one-step reduction method, integrating a plasmonic Au core with a Pd-Pt alloy shell to enable dual-mode colorimetric and photothermal detection of OFL with enhanced precision. The NPs exhibited broad-spectrum absorption, high photothermal efficiency, and stability. Based on this material, a dual-mode LFIA was developed for OFL, achieving limits of detection (LOD) of 0.059 ng mL⁻1 (colorimetric mode) and 0.038 ng mL⁻1 (photothermal mode), surpassing AuNPs-LFIA by 1.64- and 2.55-fold, respectively. Recovery test in river water and milk samples ranged from 80.72 to 115.24% with relative standard deviations (RSD) below 12.75%, demonstrating high accuracy and reliability in complex matrices. This study offers a reliable, user-friendly platform for OFL detection with potential applications in food safety and environmental monitoring.