Citation: Aydogdu, N.; Ozcelikay, G.; Ozkan, S.A. Rapid and Sensitive Electrochemical Assay of Cefditoren with MWCNT/Chitosan NCs/Fe 2 O 3 as a Nanosensor. Micromachines 2022, 13, 1348. https://doi.org/10.3390/ mi13081348 Academic Editors: Prabhu Arumugam and Shabnam Siddiqui Received: 21 July 2022 Accepted: 17 August 2022 Published: 19 August 2022 Publisher’s Note: MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affil- iations. Copyright: © 2022 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https:// creativecommons.org/licenses/by/ 4.0/). micromachines Article Rapid and Sensitive Electrochemical Assay of Cefditoren with MWCNT/Chitosan NCs/Fe 2 O 3 as a Nanosensor Nida Aydogdu 1,2 , Goksu Ozcelikay 2 and Sibel A. Ozkan 2, * 1 Department of Analytical Chemistry, Faculty of Pharmacy, Afyonkarahisar Health Sciences University, Afyonkarahisar 03218, Turkey 2 Department of Analytical Chemistry, Faculty of Pharmacy, Ankara University, Ankara 06560, Turkey * Correspondence: sibel.ozkan@pharmacy.ankara.edu.tr Abstract: In this research, a glassy carbon electrode (GCE) modified by MWCNT/chitosan NCs/Fe 2 O 3 was prepared for the determination of the cephalosporin antibiotic cefditoren (CFT) using adsorptive stripping differential pulse and cyclic voltammetry techniques. The effects of pH, the scan rate, the deposition potential, the accumulation time, and modification agents on the determination of CFT were analyzed. The results showed that the modified electrode significantly increased the oxida- tion peak current of CFT. Under optimized conditions, the MWCNT/chitosan NCs/Fe 2 O 3 /GCE nanosensor exhibited a linear response between 0.2 μM and 10 μM toward CFT. The limit of detection and quantification were determined to be 1.65 nM and 5.50 nM, respectively. Model drugs (cefdinir, cefpodoxime, cephalexin, and ceftazidime compounds) were used to enlighten the CFT oxidation mechanism. Moreover, the nanosensor was used to analyze CFT in a pharmaceutical dosage form and commercial deproteinated human serum samples. The accuracy of these methods was proven in the recovery studies, with values of 96.98 and 98.62% for the pharmaceutical dosage form and commercial deproteinated human serum sample, respectively. Keywords: cefditoren; cephalosporins; antibiotics; β-lactamases; determination; electroanalytical methods; electrochemical; voltammetry 1. Introduction Cefditoren (CFT) is a third-generation cephalosporin antibiotic. This drug is used for the treatment of biotic disorders, including skin infections, palatine tonsils, and acute and chronic bronchitis. It shows antibacterial activities for Gram-negative and Gram-positive pathogens. The dosage of CFT can be 100, 200, and 400 mg. The C max ,t max , and half-life are 3.4 mcg/L, 2.0 h, and 1.1 h, respectively. The rapid detection of antibiotics can contribute to antibiotic treatments with favorable clinical effects and a decrease in inappropriate antibiotic usage [1]. The structure of CFT, including the cephem skeleton, is shown in Figure 1. Several analytical techniques have been performed for the determination of cefditoren, including LC-MS techniques [2], voltammetrics [3], spectrophotometry [4–6], chemilumi- nescence [7], micellar liquid chromatography [8], high-performance liquid chromatogra- phy (HPLC) [5,9–13], Fourier transform infrared spectroscopy [14], potentiometry using ion-selective electrodes [15], and thin-layer chromatography (TLC) [5]. Electrochemical techniques are significant for monitoring and sensing pharmaceuticals because of their spe- cific properties such as a fast response, sensitivity, no pre-treatment, simplicity, low organic solvent consumption, and low cost versus traditional analysis methods [16]. Voltammetric techniques, including squarewave voltammetry (SWV) and differential pulse voltamme- try (DPV), have been used to determine the electroactive pharmaceutical compounds in different samples. Cyclic voltammetry (CV) has been applied to investigate the oxidation and reduction mechanisms of drug compounds [17]. It has been noted that the AdSDPV technique is more sensitive to the current obtained by the oxidation of the compound Micromachines 2022, 13, 1348. https://doi.org/10.3390/mi13081348 https://www.mdpi.com/journal/micromachines