Nano-structured MOF modified electrochemical sensors for discriminative simultaneous detection of Cu²⁺ and Hg²⁺ in seaweed

Developed novel electrochemical sensors with nano-sheet structured, addressing the low conductivity and poor stability of traditional MOFs in sensing applications. As far as we know, this is the first report. • Realized simultaneous determination of Cu²⁺ and Hg²⁺ with outstanding performance: wide linear range, low detection limit, rapid electrochemical response, excellent selectivity against interfering ions, good reproducibility, and long-term stability. • Comprehensively elucidated the sensing mechanism by integrating Laviron’s adsorption theory, involving the intrinsic electrochemical activity of MOF nanosheets and specific interactions between MOF crystalline frameworks and target metal ions. • Validated practical applicability in complex real matrices (seaweed food samples) with satisfactory accuracy and recoveries meeting international analytical standards, enabling on-site heavy metal monitoring. • Provided a rational design strategy for the development of high-performance MOF-based sensors, highlighting significant practical potential in food safety and environmental heavy metal detection. Heavy metal ion presence in food poses a severe threat to human and ecological health. It is important to achieve rapid, sensitive and efficient detection of heavy metal ions. Two novel electrochemical sensing platforms based on Ni-MOF1/GCE and Cd-MOF2/GCE modified electrodes were developed for discriminative simultaneous detection of Cu²⁺ and Hg²⁺ in seaweed food matrices. Two sensors exhibit significantly enhanced electrochemical performance compared to conventional MOF-based sensors, featuring a three-dimensional Nano-network structure and abundant accessible active sites. Under optimized differential pulse anodic stripping voltammetry (DPV) conditions, two sensors exhibited rapid responses, wide linear ranges (20–180 μM for Cu²⁺, 7–180 μM for Hg²⁺) for both Cu²⁺ and Hg²⁺, with low limit of detection (LOD, 3.00 × 10⁻⁹ M for Cu²⁺, 2.50 × 10⁻⁹ M for Hg²⁺). Benefiting from the structural characteristics, two sensors show highly selective, sensitive, long-term stability under real sample testing. Applications in real seaweed food samples demonstrated high recovery rates and validated the sensor’s reliability. A possible mechanism involving the electrochemical sensing of Cu²⁺ and Hg²⁺ was proposed by integrating laviron’s adsorption theory. This work provides superior sensors, offering promising prospects for Cu²⁺ and Hg²⁺ monitoring in environmental and agricultural safety. Ni-MOF1/GCE and Cd-MOF2/GCE sensors are constructed as electrochemical sensors with excellent simultaneous ultrasensitive determination performance for trace multiple Cu 2+ and Hg 2+ in food samples. Download: Download high-res image (420KB) Download: Download full-size image