Electrocatalytic behaviour of self-assembled Cu-chitosan/f-MWCNT on glassy carbon electrode for detection of erythromycin in various samples

Although antibiotics are class of compounds that are administered to fight bacterial infections in human and animals, its abuse is ensuing its occurrence in natural resources producing drug resistant strains, which in turn affect human health. Therefore, it is important to develop rapid and effective detection techniques for such antibiotics which are contaminating various natural resources. In this study, a novel electrochemical sensor was developed for determination of one of the most used macrolide antibiotic “Erythromycin” based on self- assembled cu-chitosan/f-MWCNT modified glassy carbon electrode. The negatively charged f-MWCNT holds the positively charged chitosan and Cu²⁺ ions, leading to formation of Cu-chitosan/f-MWCNT/GCE. FE-SEM, FT-IR, EDS as well as electrochemical methods such as CV, DPV and EIS were used to characterize formation of Cu-chitosan/f-MWCNT/GCE at every step of fabrication. From thermo-gravimetric analysis the composite was found to be stable up to 120 °C and further heating results in breakdown of the skeletal structure between 300 °C to 500 °C. Results from Cyclic voltammetry and electrochemical impedance spectroscopy indicated that after modification, the value of charge transfer resistance (Rct) decreased, and the electron transfer kinetics increased, significantly. In comparison to bare GCE, the Cu-chitosan/f-MWCNT/GCE displayed excellent electrocatalytic activity for the oxidation of erythromycin, as indicated by an increased oxidation peak current. The differential pulse peak current was linear for erythromycin concentration from 0.5 × 10⁻⁶ to 10 × 10⁻⁶ and 10 × 10⁻⁶ to 150 × 10⁻⁶M, with LOD 0.2 × 10⁻⁶M. The sensor demonstrated high selectivity, excellent stability, and impressive repeatability, during erythromycin determination. Thus, the proposed sensor demonstrates promising analytical applicability towards erythromycin detection in various samples.