Organic Polymer-Based C-A-Fe Nanozyme for Dual-Sensitive Colorimetric Detection of Hg²⁺ and Cr⁶⁺

The detection of mercury(II) (Hg2+) and chromium(VI) (Cr6+) is of significant importance due to their high toxicity and harmful effects on the environment and human health. Conventional detection methods are often expensive and time-consuming, highlighting the need for efficient alternatives. Nanozyme-based detection systems have emerged as promising solutions, offering high sensitivity, stability, and cost-effectiveness. However, many existing nanozymes contain toxic components, limiting their practical application in environmental and food safety monitoring. This study reported the development of an organic polymer-based C-A-Fe nanozyme, synthesized via a simple self-assembly chelation process and exhibiting peroxidase-like activity. This nanozyme enabled an effective colorimetric sensing approach for Hg2+ and Cr6+ detection. This nanozyme enables highly sensitive and selective colorimetric detection of Hg2+ and Cr6+ with the assistance of glutathione (GSH) and 8-hydroxyquinoline (8-HQ), achieving detection limits as low as 9.65 nM for Hg2+ and 4.13 nM for Cr6+. Moreover, the system demonstrated high recovery rates in tap water, cod, and spinach samples, confirming its potential for real-world applications in environmental and food safety monitoring.