Visualization and quantification of Hg2+ based on anti-aggregation of label-free gold nanoparticles in the presence of 2-mercaptobenzothiazole

•A highly sensitive and simple colorimetric strategy for Hg2+ detection is developed using gold nanoparticles.•The assay was based on anti-aggregation of AuNPs which could lower false positive signals.•The assay was applied to detect Hg2+ in real water and milk powder samples.•The colorimetric assay showed excellent sensitivity compared to other assays. A highly sensitive and simple colorimetric strategy for Hg2+ detection is introduced based on anti-aggregation of gold nanoparticles (AuNPs). 2-Mercaptobenzothiazole (MBT) can cause the aggregation of AuNPs due to strong covalent Au–S bond formation resulting in color change from red to blue. However, the presence of Hg2+ led the AuNPs to remain in the dispersed state because MBT prefers to interact with Hg2+ rather than AuNPs. Based on the anti-aggregation mechanism, Hg2+ can be detected by observing the color change of AuNPs solution containing MBT. The minimum detectable quantity is 0.1μM by the naked eyes, and the limit of the detection (LOD) is 6.0nM by UV–vis spectroscopy with the linear range from 0.05 to 1.0μM. Furthermore, the developed detection system is also environmental-friendly and inexpensive, which has been successfully used in lake water and milk powder samples detection.