Fabrication of sensors for the sensitive electrochemical detection of anti-tuberculosis drugs

Abstract

In this work, electrochemical biosensors have been developed and quantified the pyrazinamide, isoniazid, rifampicin, ethambutol and streptomycin drugs in various pharmaceutical samples. Electrochemical methods are versatile and powerfull analytical technique of immense value in the area of pharmaceutical analyses. In addition, due to the similarity in the biological and electrochemical reactions, it can be expected that the reduction-oxidation mechanisms occur at the electrode surface. The biologically stimulated molecules can be examined by electroanalysis and they are also outstanding tools for the detection of pharmaceutical complexes in various matrices. Although in the case of a biosensors, the analyte interacts with bioreceptor and the resultant output is measured by a specifically designed transducer. Additionally, a reliable highly sensitive and novel biosensor was developed by using a glassy carbon electrode modified with various nanomaterials. Hence horseradish peroxidase (HRP) - Multiwalled carbon nanotubes (MWCNTs)-Titanium oxide nanoparticles (TiO2NPs) fabricated glassy carbon electrode (GCE) were used for the determination of isoniazid. Similarly, copper oxide nanoparticles (CuONPs)-MWCNTs immobilized with Cytochrome c (Cyt c) on glassy carbon electrode were established for the detection of pyrazinamide. Furthermore, iron oxide nanoparticles (Fe3O4NPs) and MWCNTs composite were immobilized with Coenzyme q (Coen- q) on glassy carbon electrode for the detection of rifampicin. In addition, Cyt c immobilized with ZnONPs and MWCNTs on glassy carbon electrode for the determination of streptomycin. Finally, the glassy carbon electrode fabricated with zinc oxide nanoparticles (ZnONPs) and reduced graphene oxide (RGO) nano composite, was further immobilized with HRP to enhance the electrochemical performance of the modified electrode for the determination of ethambutol.

Electrochemical behaviour of these first line anti TB drugs to the developed biosensors were examined by using cyclic voltammetry and differential pulse voltammetry under the optimum experimental conditions such as scan rates, pH, accumulation potential, pulse amplitude, accumulation time, voltage step time, voltage step and deposition time respectively. The prepared biosensors and nanocomposites were characterized by Fourier transform infrared spectroscopy (FT-IR), transmission electron microscopy (TEM), thermo gravimetry (TGA) and x-ray diffraction (XRD). It was observed that electrochemical methods provided good and effective techniques for the determination of isoniazid, pyrazinamide, rifampicin, ethambutol and streptomycin. Compared to the other analytical methods, the limit of detection and limit of quantifications were found to be 0.0335 μM and 0.1118 μM for isoniazid, 0.0038 μM and 0.0129 μM for pyrazinamide, 0.032 µM, and 0.413 µM for rifampicin, 0.0214 μM and 0.6713 μM for ethambutol, and 0.0028 μM and 0.5628 μM for streptomycin respectively.