Simple and rapid colorimetric visualization of tetramethylthiuram disulfide (thiram) sensing based on anti-aggregation of gold nanoparticles.

Thiram is widely used in agriculture and can pose high toxicity to humans through food and soil contamination, suggesting the necessity to develop a method for convenient and rapid detection of thiram residues. Herein, we synthesized gold nanoparticles (Au NPs) encoded with 4-aminothiophenol (4-ABT) (Au NPs@4-ABT), whose aggregation process can be triggered by silver ions (Ag+), but can also be specifically inhibited by the competitive reaction between thiram and Ag+. By monitoring the color change of Au NPs@4-ABT probe, the thiram concentration can be detected within 15 min with detection limit of 0.04 μM over a linear range of 0.05-2.0 µM. This visualization method has the advantages of good sensitivity and specificity, simple operation, rapid detection, and not requiring any large instrument or sophisticated design, and its practicability has also been verified in apple and soil, indicating its great potential for on-site evaluation of thiram in real samples.