UiO-66/Carboxylated Multiwalled Carbon Nanotube Composites for Highly Efficient and Stable Voltammetric Sensors for Gatifloxacin

The excessive use of gatifloxacin (GAT) can seriously pollute the environment and damage human health. Therefore, reliable detection of its concentration is essential for environmental protection and physical health. Herein, an efficient and stable voltammetric sensor based on zirconium-based metal–organic framework/carboxylated multiwalled nanotube nanocomposites (UiO-66/MWCNT-COOH) was constructed for the determination of GAT. The morphologies, microstructures, and electrochemical properties of UiO-66/MWCNT-COOH were investigated by using various microscopic, spectroscopic, and electrochemical techniques. UiO-66/MWCNT-COOH showed good electrocatalytic activity for GAT oxidation with remarkable voltammetric response signals, which was primarily attributed to the synergistic effect from UiO-66 and MWCNT-COOH. Electrochemical kinetics studies revealed that the electrocatalytic oxidation of GAT is an irreversible and diffusion-limited reaction involving two protons and two electrons. The anodic peak current of GAT is linearly correlated with GAT concentration in the range from 0.05 to 10 μM with a low detection limit of 0.0075 μM. Moreover, UiO-66/MWCNT-COOH demonstrated high selectivity, reproducibility, and repeatability as well as extraordinary long-term stability (at least 7 weeks). The proposed UiO-66/MWCNT-COOH reliably detected trace GAT in the effluent, milk, human serum, and eye drops with satisfactory recoveries. Together with its outstanding merits such as low cost, robust response, short assay time, and good sensitivity, the proposed sensor shows enormous prospects for in situ determination of multiple antibiotics.