Gold nanoparticle-doped three-dimensional reduced graphene hydrogel modified electrodes for amperometric determination of indole-3-acetic acid and salicylic acid

Three-dimensional (3D) networked nanomaterials have attracted great interest because of their unique porous and 3D-networked structures. In this work, a series of gold nanoparticle (AuNP) doped graphene hydrogel nanocomposites (AuNP-GHs) were synthesized through hydrothermal reaction under various conditions. X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and X-ray photoelectron spectroscopy (XPS) were used to characterize the AuNP-GH. The AuNP-GH was used to modify the glassy carbon electrode (GCE) for the detection of indole-3-acetic acid (IAA) and salicylic acid (SA) using chronoamperometric measurements. Under optimum conditions, the AuNP-GH/ GCE exhibited linear response to IAA in the ranges of 0.8-4 mu M and 4-128 mu M, and to SA in the ranges of 0.8-8.4 mu M and 8.4-188.4 mu M. The detection limits (S/ N = 3) were calculated to be 0.21 mu M for IAA and 0.22 mu M for SA. The proposed sensor showed good sensitivity and stability and hence it was applied in the detection of IAA and SA in spiked samples with satisfactory results.