Rational design of lanthanide bimetallic metal-organic frameworks for machine learning-assisted dual-mode opto-electrochemical detection of carbendazim

Carbendazim (CBZ) is a widely used pesticide that poses significant health risks when present as residues in fruits and vegetables. In this study, a dual-mode opto-electrochemical sensor based on La/Eu-BTC MOF was designed for the selective and sensitive detection of CBZ in real samples. The synthesized MOF was characterized by Ultraviolet-Visible (UV/Visible) Spectroscopy, Fourier Transform Infrared (FTIR) Analysis, X-ray Diffraction analysis (XRD), Field Emission Scanning Electron Microscopy (FESEM), Transmission Electron Microscopy (TEM), and Raman spectroscopy to confirm its composition, crystallinity, and morphology. Under optimized conditions, the La/Eu-BTC MOF exhibited strong fluorescence, which was efficiently quenched upon CBZ interaction due to inner filter effect (IFE) and suppression of the antenna effect. Furthermore, machine learning-assisted modeling of fluorescence quenching enhanced quantification accuracy by effectively modeling the non-linear fluorescence response. The fluorescence sensor showed two linear response ranges (0.001–0.075 μg/mL and 10–120 μg/mL) with detection limit of 0.7 ng/mL. In addition to fluorescence, the La/Eu-BTC MOF exhibited excellent electrochemical activity toward CBZ oxidation, providing a linear range of 0.05–11.40 μg/mL with a detection limit of 0.025 μg/mL. The real sample analysis demonstrated satisfactory %recovery in the ranges 110.7%–96.16% and 98.19%–108.32% for the fluorescent and electrochemical modes, respectively. The obtained results were cross-validated against HPLC results, demonstrating good reliability and repeatability. While machine learning models further supported validation and prediction of spiked recoveries. Overall, this opto-electrochemical sensing platform provides a rapid, sensitive, and reliable approach for CBZ detection in real sample matrices, contributing to food safety and supporting Sustainable Development Goal (SDG) 3 (Good Health and Well-Being).