A “Claw-Capture” Multiplex Electrochemical Sensing Platform for Ultrasensitive and Hierarchical Detection of Hg(II) Based on Nanochannel-Confined Hollow Ce(III)-MOF Nanofibers Coupled with l -Cysteine

Abstract Herein, according to the biotoxicity characteristics of Hg(II) with “low-dose accumulation and high-dose acute injury,” we successfully designed for the first time a multiplex electrochemical sensing platform based on the ″claw-capture″ strategy for staged detection of Hg(II). The multiplex electrochemical sensing platform was fabricated based on nanochannel-confined hollow Ce(III)-MOF nanofibers coupled with l-cysteine (l-Cys), which can detect Hg(II) in environmental wastewater and complex serum samples with high sensitivity and a large-span concentration. The uniformly ordered microporous hollow Ce(III)-MOF nanofibers not only exhibit excellent anti-interference and antifouling properties through electrostatic and spatial repulsion, but also the spontaneous cycling of Ce(III)/Ce(IV) based on the strong coordination effect between l-Cys and Ce(III) and the strong covalent bond between l-Cys and Hg(II), which serves as a signal amplification tag in a multiplex electrochemical sensing platform. The strong recognition performance of l-Cys toward Hg(II) can further effectively improve the sensitivity and selectivity to distinguish potential destructive metal species. In addition, this electrochemical sensing platform selects corresponding testing methods from cyclic voltammetry (CV), square-wave voltammetry (SWV), and chronoamperometry (CA) based on the concentration range and accuracy requirements of Hg(II) detection. Therefore, the novel electrochemical sensing platform provides a convenient and fast method for precise detection of Hg(II) in complex serum samples and environmental wastewater, as well as for staged detection of Hg(II) concentration by selecting matching electrochemical testing methods.