Polyhedral MnSe microparticles with specific Hg2+-suppressed oxidase-like activity: Toward a green and low-cost turn-off method for Hg2+ detection

With the attractive advantage of catalytic signal amplification , noble metal-based peroxidase-mimicking nanomaterials have been intensively used to establish optical methods for hypertoxic Hg 2+ detection. However, in these methods the requirement of high-concentration H 2 O 2 can lead to secondary pollution, and the noble metals used result in these assays’ high cost. Therefore, exploring new categories of enzyme mimics to develop environmentally friendly and low-cost approaches for Hg 2+ sensing is highly desired. Herein we proposed a novel noble metal-free material, MnSe microparticles , featuring specific Hg 2+ -suppressed oxidase-like catalytic activity , to fabricate a green, cheap, and high-performance turn-off approach for Hg 2+ detection. The MnSe microparticles with a polyhedral structure were obtained via a one-pot solvothermal process, showing excellent oxidase-like activity to catalyze the oxidation of colorless 3,3′,5,5′-tetramethylbenzidine (TMB) to its blue product. The introduction of Hg 2+ can significantly mask their active sites via forming an inert layer of HgSe outside the MnSe microparticles, thus suppressing the TMB catalytic color reaction. Based on the turn-off principle, colorimetric quantification of Hg 2+ was realized with high sensitivity and specificity. By integrating smartphone sensing with 3D-printed accessories and paper strips, a portable platform for the convenient detection of Hg 2+ was further established, demonstrating its great practicability in real analysis.