Gold nanozyme-based paper chip for colorimetric detection of mercury ions

In this study, we developed a facile gold nanozyme-based paper chip (AuNZ-PAD) for Hg²⁺ detection. This device has the advantages of being simple, rapid, cost effective, sensitive, selective, high throughput, and applicable to onsite detection. The colorimetric mercury assay on the AuNZ-PAD is established based on the enzyme-like catalytic activity of gold nanoparticles promoted by the formation of Au-Hg amalgam, which is correlated to the intensity of the colorimetric response resulting from the catalytic reaction of 3,3',5,5'-tetramethylbenzidine (TMB) and H₂O₂. Highly sensitive and selective detection of Hg²⁺ ions is achieved in both distilled and tap water samples, indicating the feasibility and applicability of our device for the determination of mercury pollution in real samples. Moreover, AuNZ-PAD analysis using a smartphone camera eliminates the need for expensive analytical equipment, thereby increasing the practicality of field monitoring of trace Hg²⁺ compared with other sensing methods.