Amorphous Ru-Pi Nanoclusters Coated on Polypyrrole Modified Carbon Fiber Paper for Non-Enzymatic Electrochemical Determination of Cholesterol

Abstract

A facile electrochemical sensor based on Ruthenium-Phosphate (Ru-Pi) was developed by electrodeposition of Ru-Pi on Polypyrrole (PPy) modified carbon fiber paper (CFP) electrode. Phosphate buffer solutions of neutral pH containing RuCl 3 was used for voltammetric deposition of Ru-Pi on PPy/CFP electrode. The modified electrodes were characterized by High resolution transmission electron microscopy (HRTEM), High-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM), Field emission scanning electron microscopy (FESEM) with energy-dispersive X-ray spectroscopy (EDS), X-ray diffraction (XRD), Raman spectroscopy, Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS) and electroanalytical techniques. A significant amount of phosphate (Pi) and Ru centers in higher oxidation states were present on Ru-Pi film deposited on PPy/CFP substrate. Pi plays a significant role during catalyst deposition and in its activity toward determination of Cholesterol. DPV studies demonstrated that under optimum conditions, the developed sensor has displayed a wide linear dynamic range between 0.16 nM and 20.0 nM with a superior detection limit of 0.54 × 10 −10 M. The proposed method was effectively applied in the nonenzymatic determination of cholesterol at an ultralow level in human blood serum samples. The method displayed high selectivity toward cholesterol in the presence of other interfering substances.

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“…The second-generation enzymatic biosensors use electron mediators to overcome this bottleneck. 44–51 Further improvements in the assay performance may be achieved by depositing a thin film on nanostructured screen-printed electrodes. 52,53 However, the efficacies of these more sophisticated variants of the detection procedure are commonly based on the screen-printed electrode architecture, as well as the features of the counter electrode for a three-electrode system, 40 and the hematocrit correction electrode for a four-electrode system, 40 which are by no means trivial.…”