A Simple Assay for Direct Colorimetric Visualization of Trinitrotoluene at Picomolar Levels Using Gold Nanoparticles

An explosive situation: By using gold nanoparticles and taking advantage of the donor–acceptor interaction between trinitrotoluene (TNT) and cysteamine, the visualization of TNT can be achieved at picomolar levels (see picture). The color change from red to blue can be seen with the naked eye, which allows sensitive on-the-spot detection.