Reversible metal-organic polymers template enhances platinum nanoparticles self-assemblies and accelerates POD-like catalysis for rapid and ultrasensitive multiple forms mercury detection

Monitoring the distribution characteristics of various forms of mercury is crucial for understanding its biogeochemical cycling and assessing health risks. The accurate detection of inorganic and organic mercury still relies on large instruments such as CVAAS, ICP-MS, and LC-ICP-MS. Although these traditional methods can accurately analyze and differentiate mercury forms, their complexity, high cost, and inability to facilitate immediate on-site analysis at environmental sample locations represent significant limitations. Therefore, based on a reversible metal-organic polymers template for platinum nanoenzymes,we have developed a colorimetric detection method without sample pre-treatment, to rapidly and sensitively detect mercury in multiple froms. This method detected Hg2+ within a range of 0.001-5000 nM in 3 minutes, with a detection limit of 0.0006 nM (equivalent to 0.12 ng/L). Additionally, the total mercury content in samples could be quantified by this colorimetric method, enabling precise analysis of organic mercury with an accuracy on par with traditional ICP-MS. The notable enhancements in sensitivity and analysis speed could be attributed to the distinct molecular structure of the PNAs(HCl). Studies on reaction mechanisms revealed that the dense assembly of platinum nanoparticles within PNAs(HCl) and their porous external structure not only effectively protect the catalytic active sites and offer ample reaction space, thereby efficiently mimicking the POD-like enzymatic activity, but also facilitate effective and specific binding to Hg2+. To further affirm the reliability and practicality of this analysis method, a variety of real environmental water samples had been evaluated including rivers, lakes, polluted waters, and garden soil extracts. The analytical data were consistent with those obtained from traditional ICP-MS analysis. Our results demonstrated that the PNAs(HCl)-based colorimetric method offers a rapid and precise technique for the analysis of Hg2+ and organic mercury, making it ideally suited for immediate on-site analysis following environmental sample collection.