Nanocomposites of Zr(IV)-Based Metal–Organic Frameworks and Reduced Graphene Oxide for Electrochemically Sensing Ciprofloxacin in Water

Rapid determination of trace antibiotics is critical for environmental monitoring and the ecosystem. In this study, a sensitive and selective electrochemical sensor for ciprofloxacin (Cip) detection by anodic stripping voltammetry of Cu2+ is designed. Zr(IV)-based metal–organic framework (MOF) NH2–UiO-66 and reduced graphene oxide (RGO) composites are used as working electrodes, which have a large surface area with porous structure and high electrical conductivity. Because Cip can form a stable composite with Cu2+ due to the complexation reaction, the anodic stripping voltammetry method is used for Cip determination with Cu deposition on the NH2–UiO-66/RGO-modified electrode. When Cip is present, the oxidization current of Cu2+ decreases significantly due to the formation of Cu2+–Cip complex. The prepared NH2–UiO-66/RGO sensor can detect trace levels of Cip down to 6.67 nM with a sensitivity of 10.86 μA μM–1, and a linear working range from 0.02 to 1 μM, which is superior to other electrochemical Cip sensors reported previously. The sensor also shows high selectivity, reproducibility, and stability in Cip sensing. Meanwhile, the electrochemical sensor is capable to detect Cip in real water samples with satisfactory recoveries. The ultrasensitivity, rapid detection, and easy operation of the reported sensors present significant potentials for real-time analysis and monitoring of trace antibiotic contaminants in water.