A Selective Electrochemical Sensor Based on a Modified-Glassy Carbon Electrode Using f-MWCNTs-Polydopamine for Ciprofloxacin Detection

An electrochemical sensor was designed and prepared based on a modified-glassy carbon electrode using f-MWCNTs and dopamine. The dopamine is electropolymerized to form a layer of polydopamine on the surface of functionalized carbon nanotubes. Various techniques, including FE-SEM, EDS, elemental mapping, FT-IR, AFM, XRD, and Raman spectroscopy, were used to investigate different prepared catalyst features. Using cyclic voltammetry and EIS techniques, the proposed sensor's potency for ciprofloxacin detection was examined and proved. In the next step, in the DPV technique, different parameters affecting the selectivity and the sensitivity of detection, including pH, pre-concentration potential and time, MWCNTs suspension drop size, and cycle number in the electropolymerization stage, were optimized. Two linear dynamic ranges from 0.075 to 10~\mu \text{M} and from 10 to 100~\mu \text{M} were obtained for ciprofloxacin detection in the optimum condition and using the DPV technique. The detection limit was calculated to be 0.04~\mu \text{M} , and repeatability and reproducibility were found to be 3.2 and 3.3%, respectively. Afterward, the sensor's selectivity against common interfering agents was checked out, and the sensor proved to be highly selective for ciprofloxacin detection. Ciprofloxacin was determined in human plasma and urine samples with desired results at the final stage. The sensor proved to be a trustable tool for ciprofloxacin measurement in clinical and industrial applications.