Self-assembly of gold nanoparticles for the voltammetric sensing of epinephrine

New self-assembled layers composed with gold nanoparticles, cysteamine and dihydrolipoic acid deposited on bare gold template for highly sensitive and selective simultaneous sensing of dopamine in the presence of interfering ascorbic and uric acids

“…Nevertheless, the SAM layer effectively protects the metal surface against adsorption of reaction products poisonous for the electrode surface. Gold nanoparticles immobilized on the outer side of the SAM Au/DHLA/CA layer attached to the gold surface facilitate accumulation of the substance studied at the electrode-solution interface and efficiently promote tunnelling electrons between the alkane chains of the substance analysed and the electrode [65]. Thus, modification of the surface electrode not only increases the electrode surface area but also facilitates the charge transfer between the oxidized compound and the gold electrode.…”

“…Most probably, the gold nanoparticles, covalently immobilized on the top side of the self-assembled Au/DHLA/ CA layer, promote accumulation of dopamine at the electrode/ solution interface and act as an Belectron antennae,^efficient-ly tunnelling electrons between the solute and the electrode and this contributes to the increase in the electrode sensitivity towards dopamine detection [65]. Having analysed the results of our study reported in the present paper and in our previous projects as well as other results reported in literature and related to the modification of gold electrodes for dopamine sensing, we have concluded that the dopamine detection level depends to a high extent on the molecular structure that linked the surface of gold with gold nanoparticles (the lower detection limit means the possibility of detection of lower concentrations of the analyte).…”

High catalytic activity of indium tin oxide nanoparticle modified electrode towards electro-oxidation of ascorbic acid

“…On nanomaterial-based electrodes, the redox reaction was greatly enhanced, displaying reduced overpotential and improved reversibility [1][2][3]. Among the studies of gold and platinum nanoparticles deposited on conventional electrodes, a few of them compared directly with polycrystalline surface and demonstrated that the catalysis could be attributed to the nanometer size and structure [4][5][6][7]. Electrocatalytic oxidation of dopamine, NADH and ascorbic acid was also reported on carbon nanotube modified electrodes [8][9][10].…”

Lack of nano size effect on electrochemistry of dopamine at a gold nanoparticle modified indium tin oxide electrode

“…The property displays sizedependence within the nanometer range. In all previously reported work, a few papers described direct comparison between AuNPs and bulk gold electrodes to demonstrate the unique electrocatalytic property of the nanoparticle [6,8,10]. In all the other work, the observed catalysis may simply arise from the high activity of gold (not necessarily nano-sized gold) relative to the low activity base electrodes such as carbon and ITO.…”

“…Enhanced cathodic reaction of oxygen was observed on the nanoparticle-modified electrode over the bulk gold [6]. Pre-synthesized AuNPs were attached to gold disc electrodes via thiol linkers and utilized in the detection of dopamine [7], epinephrine [8], catechol [9], as well as in the electrochemical reduction of oxygen [10]. Gold nanoparticles were also loaded into a sol-gel film on a gold substrate to form a 3D nanoparticle assembly, and employed in the continuous monitoring of hydrazine [11].…”