Homogeneous voltammetric sensing strategy for lead ions based on aptamer gated methylthionine chloride@UiO-66-NH2 framework as smart target-stimulated responsive nanomaterial.

Herein an innovative electrochemical method is proposed for the determination of lead ions (Pb2+) based on a homogeneous voltammetric (HVC) sensing strategy using an aptamer gated methylthionine chloride@UiO-66-NH2 framework as a smart target-stimulated responsive material. The proposed HVC sensor exhibits excellent sensing performance: ultralow detection limit (0.166 pM) and wide linearity (5.0 pM-500.0 nM), simultaneously, it avoids electrodeposition processes and it is simple to modify the electrode compared to previous electrochemical methods for Pb2+ detection. Thus our method shows great potential in the highly efficient detection of Pb2+ and other heavy metal ions by simply altering the related specific aptamer.

Colorimetric method transforms into highly sensitive homogeneous voltammetric sensing strategy for mercury ion based on mercury-stimulated Ti3C2Tx MXene nanoribbons@gold nanozyme activity.

Nanozymes were emerged as the next generation of enzyme-mimics which exhibit great applications in various fields, but there is rarely report in the electrochemical detection of heavy metal ions. In this work, Ti3C2Tx MXene nanoribbons@gold (Ti3C2Tx MNR@Au) nanohybrid was prepared firstly via a simple self-reduction process and its nanozyme activity was studied. The results showed the peroxidase-like activity of bare Ti3C2Tx MNR@Au is extremely weak, while in the presence of Hg2+, the related nanozyme activity is stimulated and improved remarkably, which can easily catalyze oxidation of several colorless substrates (e.g., o-phenylenediamine) to form colored products. Interestingly, the product of o-phenylenediamine exhibits a strong reduction current which is considerably sensitive to the Hg2+ concentration. Based on this phenomenon, an innovative and highly sensitive homogeneous voltammetric (HVC) sensing strategy was then proposed to detect Hg2+ via transforming the colorimetric method into electrochemistry since it can exhibit several unique advantages (e.g., rapid responsiveness, high sensitivity and quantificational). Compared to the conventional electrochemical sensing methods for Hg2+, the designed HVC strategy can avoid the modification processes of electrode coupled with enhanced sensing performances. Therefore, we expect the as-proposed nanozyme-based HVC sensing strategy provides a new development direction for detecting Hg2+ and other heavy metals.