Silica-based nanoenzymes for rapid and ultrasensitive detection of mercury ions

Mercury ions are highly toxic and can cause severe damage to humans through food and water contamination, therefore, rapid and sensitive detection of Hg2+ is of vital importance. We synthesized silica-based nanoenzymes by loading Pt nanoparticles on the surface of silica nanoparticles, and the as-synthesized nanoenzyme exhibited an excellent peroxidase-like activity. It was found that silica-based nanoenzymes can specifically reduce Hg2+ to inhibit the catalytic ability of nanoenzymes. By monitoring the color change of 3,3′,5,5′-tetramethylbenzidine, the concentrations of Hg2+ were detected within 20 min. The detection limit was as low as 60 fM with a linear range between 5 pM and 5000 nM. The proposed visual method has the advantages of simple operation, low cost and fast response, and its practicability in complex lake water has also been demonstrated, suggesting its potential as a simple and powerful strategy to evaluate Hg2+ in environmental samples.