To Love and to Kill: Accurate and Selective Colorimetry for Both Chloride and Mercury Ions Regulated by Electro-Synthesized Oxidase-like SnTe Nanobelts

Abstract

Herein, SnTe nanobelts (NBs) with efficient oxidase–mimetic activity were synthesized by the simple electrochemical exfoliation method. A specific inhibition effect of Cl– on the enzymatic behavior of the pure SnTe NBs was discovered, which was accordingly used for establishing a highly feasible, sensitive, selective, and stable Cl– colorimetric assay. The detection concentration range was 50 nM to 1 mM, and the lowest detection limit was 20 nM for Cl–. In addition, a signal on-off-on route based on the SnTe NB nanozyme was designed to realize the reliable and specific detection of Hg2+. Therein, the SnTe NBs were grafted with gold nanoparticles to form a hybrid of SnTe/Au, resulting in the depression of the oxidase-like activity, which can then be recovered in the presence of the Hg2+ due to the formation of a gold amalgam. Especially, it was found that the high concentration of Cl– over 3 mM could again exert suppression influence toward the enzymatic activity of the SnTe/Au–Hg system. Based on the to-love-and-to-kill interaction between Cl– and Hg2+, the detection range for Cl– can be extended to 40 to 250 mM. In return, the assays of Cl– could avoid in advance its interference toward the accurate Hg2+ assays. We systematically clarified the oxidase-like catalytic mechanism of the SnTe-derived nanozyme systems. The as-proposed colorimetry can be successfully applied in practical samples including the sweat, human serum, or seawater/tap water, relating to cystic fibrosis, hyper-/hypochloremia, or environmental control, respectively.

A Critical Review on the Development of Optical Sensors for the Determination of Heavy Metals in Water Samples. The Case of Mercury(II) Ion

“…For example, the formation of either the stable thymine complex (T-Hg 2+ -T) or amalgams with noble metals, can reverse the inhibitory effect that certain molecules or nanoparticles have on the oxidase mimetic activity of specific nanostructures. In the presence of Hg­(II) ions, the oxidase-like activity of the indicated nanostructures is restored and the concentration of the oxidation product increases. , …”

“…In the presence of Hg(II) ions, the oxidase-like activity of the indicated nanostructures is restored and the concentration of the oxidation product increases. 28 , 29 …”

Schiff-Base Chemistry-Coupled Catechol Oxidase-Like Nanozyme Reaction as a Universal Sensing Mode for Ultrasensitive Biosensing

“…Nanozyme-based analytical chemistry is a paramount toolkit for the rational design of biosensors for the application of environmental monitoring, clinical diagnosis, and food analysis. − Although tremendous research interest has been devoted to exploring nanozyme-based biosensors, such as immunosensors and aptasensors, the sensing modes and catalytic performance to achieve the desired biosensing of analytes is challenging. The main nanozyme-catalyzed reaction members, including substrates, nanozymes, and catalytic products, can act as sensing modes because they can be responsive to external stimuli (small molecules, proteins, ions, etc.…”

Ag Aerogel-Supported Single-Atom Hg Nanozyme Enables Efficient SERS Monitoring of Enhanced Oxidase-Like Catalysis

“…After the addition of mercury salt into the Ag aerogel system, significantly promoted oxidase-like activity is achieved due to the formation of silver amalgams. 25 Interestingly, the catalytic property for oxidase mimicking is strongly correlated with the concentration of the introduced Hg 2+ , and it is surprising that the obtained Hg/Ag shows an extraordinary catalytic activity and excellent SERS enhancement when ultralow Hg 2+ concentration is used. It can be concluded that such remarkably enhanced catalytic activity for oxidase mimicking can be the result of the formation of Hg SACs, which has been proved by the results of high-angle annular dark field scanning transmission electron microscopy (HAADF-STEM) and X-ray photoelectron spectroscopy (XPS) measurements.…”