DNA-encoded MXene-Pt nanozyme for enhanced colorimetric sensing of mercury ions

MXene-based nanozymes have attracted considerable attention in the field of environmental monitoring and medical diagnostics due to their unique properties. However, the low peroxidase-like activity and limited recognition functions of pristine MXenes hinder their further practical applications. Therefore, developing an efficient surface engineering strategy is urgently needed to promote the high performance of MXene-based nanozymes. Herein, a simple, versatile, and DNA-encoded seed-growth strategy was developed for the synthesis of MXene/DNA/Pt nanocomposites, which exhibit excellent peroxidase-like activity in a sequence-dependent manner. Surprisingly, a significant inhibition in peroxidase-like activity of MXene/DNA/Pt nanocomposites by Hg2+ ions is achieved due to the specific capture of Hg2+ by the nanozyme and in situ reduction of partial Hg2+ to Hg0 on the hybrid interface. Importantly, the proposed nanozyme-based Hg2+ sensor displays prominent analytical performance in both environmental and biological fluids, with high sensitivity, selectivity, and tunable dynamic range. Additionally, integrated with a portable centrifugal microfluidic system, the sensor has the potential to enable fast sample-to-answer Hg2+ detection in a high-throughput and point-of-care format. This work not only provides an effective surface engineering strategy for the design of highly active MXene-based nanozymes but also offers a strategy for developing a multimode sensing system for multiple scenario applications.