A novel, extreme simple modification of low-cost pencil graphite electrode (PGE) by single-walled carbon nanotube/pyrenebutyric acid (SWCNT/PBA) nanostructure for sensitive and selective detection of adrenaline

The electrochemical carbon nanotube (CNT)-based sensors may provide an effective answer to the growing need for qualitative and quantitative determination of biomolecules. However employing CNTs as interface nanomaterials in various electrode matrices has been challenging for researchers. The most important issues are uniform dispersion of CNTs due to their agglomeration and their interfacial connection with electrode matrices. The superiority of this work lies in its ability to overcome these shortcomings by simple and rapid procedures while remaining negligible sensor surface fouling, but also provides high sensitive, inexpensive, and selective determination of AD molecule. Our work presents the non-covalent functionalization of Single Wall Carbon Nanotubes (SWCNTs) by Pyrenebutyric Acid (PBA) through simple pi-stacking interaction for preserving their electronic structure and preventing their agglomeration in the dispersion step to develop a novel disposable sensor with many attractive analytical performance characteristics for Adrenaline (AD) determination. SWCNTs/PBA hybrid film on a low-cost PGE support have been developed involving soaking of greatly simplified solvent-treated GPE without any further pretreatment step into successfully dispersed SWCNTs/PBA in ethanol, which is a green solvent. The surface morphology of the SWCNTs/PBA nanostructured films were evaluated using Field-emission scanning electron microscopy (FE-SEM), being correlated with the electrochemical characteristics observed by cyclic voltammetry (CV), and electrochemical impedance spectroscopy (EIS) techniques. The heterogeneous electron transfer rate constant (ks) values 0.09, 0.15 and 0.40 s-1 were obtained for Bare PGE, PGE/SWCNT, and PGE/SWCNT/PBA electrodes, respectively. The obtained ks values have been shown that modification of SWCNTs with PBA improves the analytical properties of the sensor more than those obtained at bare PGE and SWCNTs/PGE due to synergistic effects. The analytical performance of SWCNTs/PBA/PGE was evaluated for AD oxidation in optimum pH 7.0 of phosphate buffer solution in the presence of an excess amount of interfering compounds by DPV technique. The fabricated sensor showed good response with high sensitivity, low detection limit (40 nM), wide linear range (0.25-9 mu M), and excellent reproducibility and repeatability. Also, the simultaneous analyses of AD and Uric Acid (UA) reveal that the fabricated sensor could separate the electrooxidation peaks of these two mixtures and good response with low detection limit (95nM) was also obtained for UA detection. The practical applicability of the fabricated sensor has been successfully tested for the determination of AD in human serum and injection ampoule samples with 98-110% recoveries.