Laser-scribed Graphene Electrodes Functionalized with Nafion/Fe₃O₄Nanohybrids for the Ultrasensitive Detection of Neurotoxin Drug Clioquinol

Abstract

The analysis of pharmaceutical active ingredients plays an important role in quality control and clinical trials because they have a significant physiological effect on the human body even at low concentrations. Herein, a flexible three-electrode system using laser-scribed graphene (LSG) technology, which consists of Nafion/Fe 3 O 4 nanohybrids immobilized on LSG as the working electrode and LSG counter and reference electrodes on a single polyimide film, is presented. A Nafion/Fe 3 O 4 /LSG electrode is constructed by drop coating a solution of Nafion/Fe 3 O 4 , which is electrostatically self-assembled between positively charged Fe 3 O 4 and negatively charged Nafion on the LSG electrode and is used for the first time to determine a neurotoxicity drug (clioquinol; CQL) in biological samples. Owing to their porous 3D structure, an enriched surface area at the active edges and polar groups (OH, COOH, and −SO 3 H) in Nafion/Fe 3 O 4 /LSG electrodes resulted in excellent wettability to facilitate electrolyte diffusion, which gave ∼twofold enhancement in electrocatalytic activity over LSG electrodes. The experimental parameters affecting the analytical performance were investigated. The quantification of clioquinol on the Nafion/Fe 3 O 4 /LSG electrode surface was examined using differential pulse voltammetry and chronoamperometry techniques. The fabricated sensor displays preferable sensitivity (17.4 μA μM –1 cm –2 ), a wide linear range (1 nM to 100 μM), a very low detection limit (0.73 nM), and acceptable selectivity toward quantitative analysis of CQL. Furthermore, the reliability of the sensor was checked by CQL detection in spiked human blood serum and urine samples, and satisfactory recoveries were obtained.

Quantification of Neuronal Cell-Released Hydrogen Peroxide Using 3D Mesoporous Copper-Enriched Prussian Blue Microcubes Nanozymes: A Colorimetric Approach in Real Time and Anticancer Effect

“…Similarly, the results revealed a remarkable linear relationship between log I pc and log υ, as depicted in Figure S3 ( I pc (μA) = 0.536 × (mV 1/2 s 1/2 ) + 0.743; R 2 = 0.995). Notably, the slope value closely approached the theoretical value of 0.5, a clear indication of the electrode reaction being governed by a diffusion-controlled process . The irreversible diffusion-controlled electrochemical process can be elegantly described by the Laviron equation (eq ), which establishes the profound relationship between Epa and υ: Epa = E 0 + ( RT / α nF ) ln ( italicRTK 0 / α nF ) + ( RT / α nF ) ln nobreak0em0.25em⁡ υ In this context, E 0 represents the standard electrode potential (V), while α represents the electron transfer coefficient.…”

“…Notably, the slope value closely approached the theoretical value of 0.5, a clear indication of the electrode reaction being governed by a diffusion-controlled process. 70 The irreversible diffusioncontrolled electrochemical process can be elegantly described by the Laviron equation (eq 10), which establishes the profound relationship between Epa and υ:…”

Dual Colorimetric/Electrochemical Detection of Salmonella typhimurium Using a Laser-Induced Graphene Integrated Lateral Flow Immunoassay Strip

“…Nafion was used to modify the WE because its hydrophilic side chains can functionalize graphene, resulting in improving a chemically bonded graphene and preventing graphene delamination. 32 The Nafion-modified LIG revealed a thin layer coated on the graphene sheet (Figures 3f and S7d). The surface roughness was also investigated by confocal laser scanning microscopy (CLSM), corresponding to the SEM results.…”

“…Energy-dispersive X-ray (EDX) spectroscopy analysis revealed C (13.90%), Cl (1.17%), and Ag (84.93%) elements, confirming the presence of AgCl. Nafion was used to modify the WE because its hydrophilic side chains can functionalize graphene, resulting in improving a chemically bonded graphene and preventing graphene delamination . The Nafion-modified LIG revealed a thin layer coated on the graphene sheet (Figures f and S7d).…”

Au‐Modified Carbon Electrodes Produced by Laser Scribing for Electrochemical Analysis of Probiotic Activity

“…Although kraft cardboard provides a versatile substrate for fabricating electrochemical sensors via laser scribing, [9] the electrical properties of the resultant electrodes depend on several experimental variables including the selection of the engraver. [34,[39][40][41] Thus, the effect of the scribing parameters (laser power, lateral speed, frequency, and the distance of the substrate from the laser focal plane (the degree of defocusing) were systematically evaluated to achieve the lowest electrical resistance of the electrodes. Additionally, the effect of the borate treatment was assessed by comparing the electrochemical performance of the electrodes with that of electrodes previously described electrodes.…”