A portable paper-based colorimetric sensing platform based on I/N co-doped carbonized polymer dot nanozyme for smartphone-assisted visual monitoring of Hg2+

I/N co-doped carbonized polymer dot nanozyme was synthesized using DTA, PEI and RhB as precursors. • The DAP CPDs exhibited exceptional peroxidase-like activity, fluorescence property and specific recognition of Hg 2+ . • A portable smartphone-assisted paper-based colorimetric sensing platform for on-site visual detection of Hg 2+ was constructed. • The proposed sensing platform has simplicity, portability, and potential versatility. Mercury ion (Hg 2+ ) pollution poses a serious threat to ecosystems and human health owing to its high toxicity, environmental persistence, and bioaccumulative nature. The development of rapid, cost-effective, on-site visual detection methods for Hg 2+ is paramount but challenging. In this work, we developed a novel iodine/nitrogen co-doped carbonized polymer dots nanozyme (DAP CPDs) via a simple hydrothermal method, which exhibits excellent peroxidase-like activity. Based on the specific inhibitory effect of Hg 2+ on the enzymatic activity of DAP CPDs, a solution-based colorimetric sensor was constructed for the rapid and sensitive visual detection of Hg 2+ , achieving a detection limit of 13.21 nM. Furthermore, A smartphone-assisted, portable paper-based sensing platform was developed by integrating smartphones with paper devices, enabling rapid, cost-efficient, convenient and on-site visual analysis of Hg 2+ in real water samples. This work not only offers insights into the design of high-performance carbonized polymer dot nanozymes, but also presents a practical and portable tool for the on-site monitoring of heavy metal ions in the environment. Schematic diagram of the preparation of DAP CPDs nanozyme and the detection of Hg 2+ by smartphone-based paper device colorimetric platform. Download: Download high-res image (387KB) Download: Download full-size image