Modified glassy carbon electrode with AuNPs using cis-[RuCl(dppb)(bipy)(4-vpy)]+ as crossed linking agent

This work links aspects of non-covalent interaction among gold nanoparticles (AuNPs) and ruthenium complexes, which were used to modify the surface of the glassy carbon electrode (GCE), without the necessity of a sulfur substrate with a covalent bond between gold–sulfur (Au–S), to keep the AuNPs onto the surface of the electrode. The AuNPs were synthesized by the method of encapsulation by citrate conferring on them a negative charge. The ruthenium complex [RuCl(dppb)(bipy)(4-vpy]+ was synthesized by ligand exchange in its coordination sphere, giving it a positive charge. A thin film of [RuCl(dppb)(bipy)(4-vpy)]+ was generated onto the surface of glassy carbon electrode (GCE), using cyclic voltammetry, under potential cycling between −0.9 and −2.4 V, to produce the CGE–Ru+ electrode. Afterward, the GCE–Ru+ electrode was kept in a colloidal suspension of AuNPs for 1 h to incorporate them onto the surface of GCE–Ru+ by electrostatic interaction. The resulting electrode GCE–Ru–AuNPs was finally washed with water to remove the excess of AuNPs and it was used to acetaminophen detection by cyclic voltammetry. To find the optimum analysis conditions of the modified electrode, studies were conducted to understand; which were: the number of cyclic voltammograms to produce the film, dip-coating time in AuNPs, pH, scan rate and repeatability. The Ru–AuNPs aggregates were analyzed by UV–Vis spectroscopy (UV–Vis), Fourier transform infrared spectroscopy–attenuated total reflectance (FTIR–ATR), nuclear magnetic resonance of phosphorus (31P{1H} NMR), cyclic voltammetry (CV); scanning electron microscopy with energy dispersive spectroscopy (SEM–EDS) and transmission electron microscopy with energy dispersive spectroscopy (TEM–EDS). The X-ray structure of [RuCl(dppb)(5,5′-Me-bipy)(4-vpy)](PF6) was determinate.

The interaction among ruthenium cationic complexes and gold nanoparticles (AuNPs−) were accompanied by SEM–EDS and TEM–EDS measurements, indicating to be electrostatic interactions. Therefore it was used to add AuNPs on the surface of glassy carbon electrode, without Au–S covalent bond, using the [RuCl(dppb)(bipy)(4-vpy)]+, such as crossed linking agent.Figure optionsDownload as PowerPoint slide