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

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.