Nanostructured ferrite-based non-enzymatic electrochemical sensors for drug detection

The advancement in nanotechnology has encouraged research into their application across various fields, including medical diagnosis. A currently expanding research area involves the utilization of nanomaterials in the development of electrochemical sensors for drug detection. This study focuses on the feasibility of using nano-oxides, specifically zinc ferrite, copper ferrite, and cobalt ferrite, in the fabrication of non-enzymatic electrochemical sensors to enhance the detection capabilities of paracetamol and cyclophosphamide. The ferrites, synthesized via the autocombustion method, underwent characterization utilizing Raman spectroscopy and field emission scanning electron microscopy to verify their synthesis accuracy and probe their morphological attributes, respectively. The synthesized ferrites manifested uniform morphology, with dimensions ranging between 30 to 50 nm. These materials were subsequently utilized to functionalize the working electrode of commercially available screen-printed carbon electrodes through drop-casting technique. Performance evaluation of the new sensors was conducted via cyclic voltammetry measurements, comparing the results with those obtained with a bare sensor. Regarding paracetamol detection, the modified sensors exhibited a significant increase in oxidation current upon exposure to a 1.0 mM paracetamol solution, confirming the advancement in analytical performance. Investigation into the kinetics of redox reactions, by varying the scan rate from 50 mV/s to 300 mV/s, revealed the presence of freely diffusing quasi-reversible systems. Exploiting the Laviron model and the Randles-Sevčik equation, the electron transfer coefficient, kinetic constant rate, and diffusion coefficient were determined. Variations in paracetamol solution concentration from 0.5 mM to 3.0 mM allowed the derivation of the calibration curves, sensitivity and limit of detection (LoD). Compared to the unmodified sensor, characterized by a sensitivity of 24.05 ± 0.27 μA/mM and a LoD of 4.38 ± 0.08 μM, the modified sensors exhibited enhanced performance. Notably, zinc ferrite modified sensor yielded the highest results, with a sensitivity of 28.27 ± 0.43 μA/mM and a LoD of 2.13 ± 0.07 μM. In the case of cyclophosphamide detection, varying the concentration of the cyclophosphamide solution (10, 50, 100 μM) enabled the derivation of calibration curves, sensitivity, and detection limit. Compared to the unmodified sensor, which exhibited no detection capability at these low concentrations of cyclophosphamide solution, the sensor modified with copper ferrite demonstrated better and consistent performance, with a sensitivity of 20.16 ± 1.32 nA/μM and a LoD of 8.07 ± 0.53 μM. In conclusion, this study highlights the significant potential of these materials in enhancing sensor efficacy. Promising prospects suggest the need for further investigations and research on other pharmaceutical compounds to broaden the application of these materials in the sensing and biosensing field.