The Fabrication of Stable Gold Nanoparticle-Modified Interfaces for Electrochemistry

Abstract

Forming stable gold nanoparticle (AuNP)-modified surface is important for a number of applications including sensing and electrocatalysis. Herein, tethering AuNPs to glassy carbon (GC) surfaces using surface bound diazonium salts is investigated as a strategy to produce stable AuNP surfaces. GC electrodes are first modified with 4-aminophenyl (GC-Ph-NH(2)), and then the terminal amine groups are converted to diazonium groups by incubating the GC-Ph-NH(2) interface in NaNO(2) and HCl solution to form a 4-phenyl diazonium chloride-modified interface (GC-Ph-N(2)(+)Cl(-)). Subsequently AuNPs are immobilized on the interface by electrochemical reduction to give a 4-phenyl AuNP-modified interface (GC-Ph-AuNP). For comparison, 4-aminophenyl AuNP- and 4-thiophenol AuNP-modified GC interfaces (GC-Ph-S-AuNP and GC-Ph-NH-AuNP), in which AuNPs are tethered to the surfaces by forming S-Au and NH-Au bond, respectively, were also prepared. Cyclic voltammetry, electrochemical impedance spectroscopy, X-ray photoelectron spectroscopy, and scanning electron microscopy are used to characterize these fabricated interfaces. The AuNP on GC-Ph-AuNP surfaces demonstrate good stability under sonication in Milli-Q water, during electrochemical treatment in 0.05 M H(2)SO(4) solution, and over several weeks. By contrast, the GC-Ph-NH-AuNP and GC-Ph-S-AuNP surfaces showed significant particle losses under equivalent conditions.

A Molecule with Dual Functionality 4‐Aminophenylmethylphosphonic Acid: A Comparison Between Layers Formed on Indium Tin Oxide by In Situ Generation of an Aryl Diazonium Salt or by Self‐Assembly of the Phosphonic Acid

“…As shown in Figure 6, the Ru(NH 3 ) 6 3 + redox signal is almost completely suppressed by the ITO-Ar-NH 2 surface. However, the electrochemical reactivity of Ru(NH 3 ) 6 3 + is recovered after the covalent attachment of AuNPs meaning the electronic conduction pathway between the AuNPs and the ITO substrate is efficient, and reinforcing our previous studies [10].…”

“…This molecule possesses two amines that can be converted to aryl diazonium salts. It can be used to modify the electrode and anchor the particles with covalent linkages [10]. The ITO electrodes were first modified with the 4-phenylenediamine by in situ diazotization of one of the two amino groups.…”

“…To achieve highly stable electrode-organic layer-nanoparticle constructs is contingent on three aspects of the assembly: the stability of the layer itself, its attachment on ITO and its bond to the nanoparticles. We have recently shown that stable bonds between electrodes and gold nanoparticles can be achieved using aryl diazonium salt derived layers where a strong bond is formed, after the diazo group is lost, to both the macroelectrode and the nanoparticle [10]. The main drawback of this approach is that aryl diazonium salt derived layers are often multilayers rather than welldefined monolayers [9].…”

An Immunosensor for Pathogenic Staphylococcus aureus Based on Antibody Modified Aminophenyl-Au Electrode

“…The use of electroreduction of aryl diazonium salts provides higher stability with respect to long-term storage in air, potential use in cyclic voltammetry under acidic conditions, and a wider potential window for subsequent electrochemistry [25]. Diazonium salt molecules, modified with various functional groups, have been used for the immobilization of nanoparticles [26], DNA [27], enzymes [28], carbon nanotubes [29,30], proteins, antibodies and electroactive species [31][32][33][34] on GC, Si, and Au surfaces. Moreover, applying an electrochemical potential to the specific electrode (chip) allows biomolecule immobilization which should be compatible with the production of biochip microarrays for multidetection.…”

From an Organometallic Monolayer to an Organic Monolayer Covered by Metal Nanoislands: A Simple Thermal Protocol for the Fabrication of the Top Contact Electrode in Molecular Electronic Devices

“…As shown in Figure 1, the characteristic phosphorus peak which is present in the pristine films of 1 disappears after the annealing and subsequent rinsing process, indicating that the triphenylphosphine (PPh 3 ) group of 1 is lost after the thermal treatment. In addition, the Au4f region for the film after the annealing process shows two peaks at 83.81 and 87.48 eV, attributable to Au(0) [24][25][26] whilst the pristine monolayer shows two intense peaks at 85.04 and 88.74 eV, attributable to Au(I), [27][28] and two weaker peaks at 83.88 and 87.56 eV attributable to Au(0) that is probably formed during the irradiation process necessitated for recording the XPS spectrum.…”