Ultrasensitive and precise point-of-care detection of mercury ions using pressure and temperature as readout based on mercury-regulated catalase and peroxidase mimetic activities of Au nanoparticles decorated covalent organic polymer

Abstract

The development of innovative approaches for portable, highly sensitive, and selective detection of mercury ions holds immense value for both biochemical and environmental analysis. In this study, a simple, user-friendly, label-free and cost-effective multimodal point-of-care testing (POCT) platform was established based on in situ-grown gold nanoparticles (Au NPs) embedded in a porous covalent organic polymer (COP-180). This novel platform utilizes a unique combination of pressure, temperature, and colorimetric signals for multi-modal readout to realize precise and specific identification of Hg(II). In an alkaline environment, Hg²⁺ triggers the catalase-like activity of Au/COP-180, promoting the decomposition of H₂O₂ into oxygen (O₂), producing a detectable pressure signal. Conversely, in acidic conditions, Hg²⁺ enhances the peroxidase-like activity of the Au/COP-180, leading to the generation of reactive oxygen species (•OH) that contribute to colorimetric and photothermal signals. This platform exhibits excellent linearity across all three detection modes, with detection limits of 9 nM for pressure, 27.4 nM for colorimetry, and 0.1 μM for temperature. Furthermore, this approach demonstrated satisfactory results for detecting mercury ions in real water samples. This innovative multimodal POCT strategy provides a robust and operationally simple solution for detecting heavy metal ions with high sensitivity and accuracy, particularly in resource-limited settings.

Keywords: Au/COP-180; Colorimetric; Mercury; Photothermal; Point-of-care testing; Pressure.