Novel electrochemical platforms for the detection of both clinical disorder biomarker and environmental pollutants using graphitic carbon nitride-conducting oligomer composites

Abstract

Kynurenic acid (KYNA) is an endogenous tryptophan (Try) metabolite that has anticonvulsant and neuroprotective activities. Many diseases and disorders have been attributed to the kynurenine pathway, including Alzheimer’s disease, amyotrophic lateral sclerosis, Huntington’s disease, AIDS dementia complex, malaria, cancer, depression, and schizophrenia, where tryptophan and kynurenine imbalances have been found. In addition to that, screening of environmental pollutants, especially nitrobenzene (NB) from wastewater discharges, is an essential aspect of governmental and commercial company observation. NB is prolonged exposure causes major harm to human health and environmental disruption. As a result, the development of innovative sensors capable of detecting KYNA and NB traces in blood serum and water, respectively, is important. This work proposes an innovative electrochemical clinical and environmental based sensor for KYNA and NB detection and that is based on a graphitic carbon nitride (GCN)-conducting oligomer composite fabricated glassy carbon (GC) electrode. Melamine was directly pyrolyzed to yield the GCN used in this study. The prepared exfoliated GCN (E-GCN) has a sheet-like structure, demonstrated by the scanning electron microscopy (SEM) image and the Energy-dispersive X-ray analysis (EDAX) analysis confirmed the elemental composition. The potentiodynamic technique was used to create the E-GCN composite with oligo 3-amino-5-mercapto-1,2,4-triazole (AMTa). E-GCN-oligomer composites were successfully formed, as evidenced by additional analysis of the developed composites performed utilizing SEM, X-ray diffraction spectroscopy (XRD), attenuated total reflectance-Fourier transform infrared spectroscopy (ATR-FT-IR) and X-ray photoelectron spectroscopy (XPS) techniques. The electrochemical impedance spectroscopy (EIS) studies demonstrate that the electron transfer reaction was easier at the GC/E-GCN-oligo AMTa electrode than it was at the bare GC, GC/GCN, and GC/oligo AMTa electrodes. The electrocatalytic activity of GCN, oligo AMTa, and GCN-oligo AMTa fabricatedelectrodes regardingthe oxidation of KYNA and reduction of NB was investigated further. Contrasting the E-GCN-oligo AMTa modified electrode to the bare GC, E-GCN, and oligo AMTa modified electrodes, it was discovered that the latter two exhibited lower electrocatalytic activity towards the oxidation of KYNA and reduction of NB. The enhanced electrocatalytic activity of KYNA and NB at the fabricatedE-GCN-oligo AMTa electrode was ascribed to its improved conductivity, greater electroactive surface area, and faster electron transfer rate. Then the developed bio and environmental sensors identified KYNA and NB within a range of 1 nM to 0.5 mM KYNA and 80 nM to 1 mM NB, with limits of detection of 1.8 × 10 M and 3.7 10 M, respectively. The suggested approach was implemented to use by analyzing KYNA in human blood serum and NB in lake water samples.