An optical and electrochemical sensor based on l-arginine functionalized reduced graphene oxide

Abstract

The electrochemical and photochemical properties of graphene derivatives could be significantly improved by modifications in the chemical structure. Herein, reduced graphene oxide (RGO) was functionalized with l-arginine (l-Arg) by an amidation reaction between the support and amino acid. Deposition of a powerful ligand, l-Arg, on the optically active support generated an effective optical chemosensor for the determination of Cd(II), Co(II), Pb(II), and Cu(II). In addition, l-Arg-RGO was used as an electrode modifier to fabricate l-Arg-RGO modified glassy-carbon electrode (l-Arg-RGO/GCE) to be employed in the selective detection of Pb(II) ions by differential pulse anodic stripping voltammetry (DP-ASV). l-Arg-RGO/GCE afforded better results than the bare GCE, RGO/GCE, and l-Arg functionalized graphene quantum dot modified GCE. The nanostructure of RGO, modification by l-Arg, and homogeneous immobilization of resultant nanoparticles at the electrode surface are the reasons for outstanding results. The proposed electrochemical sensor has a wide linear range with a limit of detection equal to 0.06 nM, leading to the easy detection of Pb(II) in the presence of other cations. This research highlighted that RGO as a promising support of optical, and electrochemical sensors could be used in the selective, and sensitive determination of transition metals depends on the nature of the modifier. Moreover, l-Arg as an abundant amino acid deserves to perch on the support for optical, and electrochemical determination of transition metals.

Three-Dimensional Conductometric Network Based on Reduced Graphene Oxide for Soil pH Sensors

“…The intensity ratio of D to G peaks ( I D / I G ) that determines the degree of disorder of the graphene lattice is 1.01 in the case of GO which increases to 1.23 for 3DGA samples, indicating the existence of defect-rich graphene skeleton after being functionalized and reduced. The Raman analysis results are consistent with earlier investigations. ,,, XRD profiles of GO powder and 3DGA samples are displayed in Figure f. As can be seen, a sharp diffraction peak centered at around 2θ = 11.2° is observed, which is indexed to the (001) plane of pure GO samples. , However, the as-synthesized 3DGA composites are characterized by a broad diffraction peak at 2θ = 25.2° related to the (002) plane of stacked graphene sheets along with the complete disappearance of GO representative peak (2θ = 11.2°) .…”

“…The possible pH sensing mechanism of the 3DGA-based microsensor is presented in Figure c. As per the earlier studies, the loading of l -arginine on the 3D graphene offers free electrons as the majority of charge carriers in the nanocomposite structure . Among the surface oxygen functional groups of the 3DGA-based sensing film, the epoxide and carbonyl groups are insensitive, while the carboxylic and amine groups are sensitive to pH .…”

“…As per the earlier studies, the loading of L-arginine on the 3D graphene offers free electrons as the majority of charge carriers in the nanocomposite structure. 25 Among the surface oxygen functional groups of the 3DGA-based sensing film, the epoxide and carbonyl groups are insensitive, while the carboxylic and amine groups are sensitive to pH. 46 In an aqueous environment, the carboxylic acid functional groups lose protons to produce carboxylate ions (−COO − ) due to their smaller pK a value ranging from 2 to 5.…”

“…In this study, a facile and efficient approach has been utilized to synthesize 3D graphene/ l -arginine (3DGA) composite with open porous architectures via the reduction of graphene oxide (GO) with l -arginine. − According to earlier studies, numerous types of reducing agents have been employed to reduce GO. However, the toxicity and hazardous nature of the majority of chemical compounds remain always a concern. , l -arginine has been chosen as a green reducing agent owing to its low cost, abundance, and environmentally friendly nature. − The fabricated 3DGA-based conductometric pH microsensor achieved a sensitivity of 97 μS/pH and response of 650% with buffer solutions over the pH range of 3–10. The same microsensor is used to examine the pH of soil solutions prepared using deionized water and with different concentrated (1–20 mM) solutions of calcium chloride (CaCl 2 ).…”

Determination of trace amount of iron cations using electrochemical methods at N, S doped GQD modified electrode

“…One of the important components in electrochemical methods is the working electrode, the modification of which with a suitable modifier can greatly improve the performance compared to the bare electrode 27 , 28 . For the development of iron sensors and biosensors, organic and biological ligands with pyridine, carboxylate, phosphate, and hydroxamate functional groups are interesting detection systems in analytical chemistry.…”