A selective and sensitive electrochemical sensor for labetalol detection based on a Zr–BDC MOF/MWCNT modified electrode

Abstract

In this study, a novel electrochemical sensor is developed for the highly selective and sensitive detection of labetalol (LAB), a β-blocker, using a highly porous material composed of a zirconium-based metal–organic framework (Zr–BDC MOF) integrated with multi-walled carbon nanotubes (MWCNTs). Various transition metal-based MOFs, including Zr–BDC, Co-BDC, Cu-BDC, Ag-BDC, and Y-BDC, were synthesized via a solvothermal route. These MOFs were incorporated with MWCNTs to fabricate composite materials used to modify glassy carbon electrodes (GCEs). Among the prepared composites, the Zr–BDC/MWCNT/GCE exhibited superior electrocatalytic performance toward LAB oxidation. This enhanced activity is primarily attributed to its high surface area, enhanced electrical conductivity, and the synergistic effect between the Zr–BDC framework and MWCNTs, which collectively reduce the activation energy for the oxidation process. The Zr–BDC MOF was thoroughly characterized both morphologically and electrochemically using a range of analytical techniques. Calibration based on differential pulse voltammograms (DPVs) revealed a linear response for LAB oxidation peak current in the concentration range of 0.1 to 40 μM, with a sensitivity of 2.53 μA μM⁻¹. The detection and quantification limits were calculated as 6.5 × 10⁻⁸ M and 19.7 × 10⁻⁸ M, respectively, based on a signal-to-noise ratio of 3. The sensor exhibited excellent recovery rates (97–101%) for LAB detection in pharmaceutical formulations and real samples like urine, confirming its reliability and accuracy in complex matrices.