A dual-mode lateral flow immunoassay based on DTTC-functionalized sea urchin-like gold nanoprobes for reliable detection of progesterone residues.

Abstract

Progesterone (P4) is an important steroid hormone involved in mammalian reproductive regulation, and its accurate detection in animal-derived biological samples and foods is essential for reproductive status assessment and food safety monitoring. Herein, a colorimetric-photothermal dual-mode lateral flow immunoassay (LFIA) was developed using 3,3'-diethylthiatricarbocyanine iodide (DTTC)-functionalized sea urchin-like gold nanoparticles (Au-Ur@DTTC) as a dual-signal probe for P4 detection. The composite nanoprobe exhibited broad absorption across the visible-near-infrared region and a photothermal conversion efficiency of 33.3%, enabling simultaneous generation of visual colorimetric and near-infrared photothermal signals. Under optimized conditions, the limits of detection for the colorimetric and photothermal modes were 0.207 ng mL-1 and 0.163 ng mL-1, respectively, representing enhanced sensitivity compared with conventional gold nanoparticles (AuNP)-based LFIA. The recoveries in spiked milk and pork matrices ranged from 92.30% to 110.80%, while the relative deviations in beagle serum samples ranged from -9.21% to 10.46%, with relative standard deviations below 10%. This dual-mode platform requires minimal instrumentation and enables both rapid on-site screening and laboratory-based quantitative analysis, providing a practical strategy for P4 detection in complex food and biological matrices.