Self-Assembly of Monolayer-Coated Silver Nanoparticles on Gold Electrodes. An Electrochemical Investigation

2003 ◽  
Vol 68 (8) ◽  
pp. 1395-1406 ◽  
Author(s):  
Massimo Marcaccio ◽  
Massimo Margotti ◽  
Marco Montalti ◽  
Francesco Paolucci ◽  
Luca Prodi ◽  
...  
Keyword(s):  
Silver Nanoparticles ◽  
Self Assembly ◽  
Electrical Response ◽  
Significant Loss ◽  
Outer Side ◽  
Organic Layer ◽  
Nanoparticle Array ◽  
Self Assembled Monolayer ◽  
Electroactive Material ◽  
Self Assembled

Redox behaviour of an array of dodecanethiol-coated silver nanoparticles, self-assembled on the gold electrode surface by dithiol linkers, is dominated in aqueous electrolytes by a reversible faradaic process that has been attributed to the anodic oxidation of silver nanoparticles. The nanoparticle array may be switched between the oxidised and reduced states repeatedly without any significant loss of electroactive material, thus showing a remarkable stability under electrochemical conditions. The mainly capacitive high-frequency electrical response of the nanoparticle array/electrolyte interface is characterised by a low value of capacitance, typical of a self assembled monolayer (SAM) of long-chain alkanethiols on gold; it has been associated with the compact organic layer interposed between the nanoparticles and the gold substrate. At lower frequencies, the interface displays a poorer electrical behaviour with both capacitive and resistive elements, which was associated with the more disordered organic layer located on the outer side of the film.

Surfaces Matter

2009 ◽  
Vol 1209 ◽  
Author(s):  
Eric L. Bruner
Keyword(s):  
Self Assembly ◽  
Scratch Resistance ◽  
Consumer Products ◽  
Molecular Structures ◽  
Self Assembled Monolayer ◽  
Phosphonic Acids ◽  
Princeton University ◽  
Self Assembled ◽  
Strong Attachment ◽  
Functional Areas

AbstractAculon, Inc. specializes in inventing and commercializing unique molecular-scale surface and interfacial coatings leveraging nanotechnology discoveries made at Princeton University. These coatings can be classified into three functional areas; non-stick, pro-stick/adhesion, and anti-corrosion. The company has formulated coating solutions and processes for numerous markets including optical, display, electronics, consumer products and industrial coatings. These specialized coatings outperform all known alternatives in characteristics such as adhesion, stain resistance, and scratch resistance. Fueling the company’s commercialization efforts are its proprietary Self-Assembled Monolayer of Phosphonates (SAMP) technology. The commercialization of SAMP treatments can be used for a variety of applications including imparting hydrophobicity, adhesion, or corrosion inhibition to numerous substrates. For surface treatments to be effective, they must be mechanically and chemically stable under conditions experienced in the intended area of use. Aculon’s proprietary Self-Assembled Monolayer of Phosphonates methodology can impart any of these properties as desired to metals, metal oxides and even some polymer surfaces by drawing on its library of structurally tailored phosphonic acids. The secret to the commercialization is covalent bonding, which creates a uniquely strong attachment between the SAMP and the substrate. Because the SAMP is one approximately 1.5 nm thick, it completely covers the material to which it is applied, and assures total surface coverage regardless of the type or texture of that material. The composition of the SAMP determines the properties that it imparts to its substrate. In 1998, Professor Jeffery Schwartz of Princeton University discovered that well-ordered monolayers of phosphonates could be formed by self-assembly on a wide variety of oxide and oxide-terminated surfaces. At that time Professor Schwartz and his team also discovered that a simple dip process enabled SAMP formation on substrates of complex structures and geometries, as well as traditionally “unreactive” surfaces. The research showed that SAMP adhesion to oxides was mechanically strong and resisted removal by hydrolysis and oxidation. It showed further that by using the dip method, SAMPs of a variety of molecular structures, including aliphatic, aromatic, and heteroaromatic, could be prepared. Commercialization of SAMPs proves that such surface-bound phosphonates can dictate control of the surface properties of myriad substrates and that they can be implemented using well-known industrial techniques and conditions. These processes can be scaled to meet the needs of large or small facilities, and can be applied to surfaces of nearly any size or shape without special needs. Based on the needs of the producer, surface modification can be completed during the time of manufacturing or can be performed as a post-production step.

scholarly journals Electrochemistry Study of Permselectivity and Interfacial Electron Transfers of a Branch-Tailed Fluorosurfactant Self-Assembled Monolayer on Gold

Molecules ◽  
2018 ◽  
Vol 23 (11) ◽  
pp. 2998 ◽  
Author(s):  
Shanshan Li ◽  
Qingying Luo ◽  
Zhiqing Zhang ◽  
Guanghui Shen ◽  
Hejun Wu ◽  
...  
Keyword(s):  
Self Assembly ◽  
Electrochemical Impedance ◽  
Click Reaction ◽  
Hydration Shell ◽  
Self Assembled Monolayer ◽  
Tunneling Mechanism ◽  
Assembly Technique ◽  
Hydration Resistance ◽  
Self Assembled ◽  
Electron Transfers

We investigated the permselectivity and interfacial electron transfers of an amphiphilic branch-tailed fluorosurfactant self-assembled monolayer (FS-SAM) on a gold electrode by cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). The FS-SAM was prepared by a self-assembly technique and a “click” reaction. The barrier property and interfacial electron transfers of the FS-SAM were also evaluated using various probes with different features. The FS-SAM allowed a higher degree of permeation by small hydrophilic (Cl− and F−) electrolyte ions than large hydrophobic (ClO4− and PF6−) ones. Meanwhile, the redox reaction of the Fe(CN)63− couple was nearly completely blocked by the FS-SAM, whereas the electron transfer of Ru(NH3)63+ was easier than that of Fe(CN)63−, which may be due to the underlying tunneling mechanism. For hydrophobic dopamine, the hydrophobic bonding between the FS-SAM exterior fluoroalkyl moieties and the hydrophobic probes, as well as the hydration resistance from the interior hydration shell around the oligo (ethylene glycol) moieties, hindered the transport of hydrophobic probes into the FS-SAM. These results may have profound implications for understanding the permselectivity and electron transfers of amphiphilic surfaces consisting of molecules containing aromatic groups and branch-tailed fluorosurfactants in their structures.

Corrosion protection of stainless steel by a self-assembled organosilane bilayer

2014 ◽  
Vol 61 (5) ◽  
pp. 307-313 ◽  
Author(s):  
Hairen Wang ◽  
Minya Li ◽  
June Qu ◽  
Zhiyong Cao ◽  
Geng Chen ◽  
...  
Keyword(s):  
Contact Angle ◽  
Stainless Steel ◽  
Corrosion Inhibition ◽  
Self Assembly ◽  
Ethanol Solution ◽  
Organic Layer ◽  
Stainless Steel Surface ◽  
Nacl Solution ◽  
Content Type ◽  
Self Assembled

Purpose – The purpose of this paper is to construct a self-assembled double layer of organosilane on the surface of stainless steel and to investigate its corrosion inhibitive capability. Design/methodology/approach – A monolayer of 3-glycidoxypropyltrimethoxysilane (GPTMS) was grafted onto an oxidized AISI 430SS (AISI 430 stainless steel) surface substrate from dry toluene solution. The hydrolysis of 1H,1H,2H,2H-perfluorodecyltriethoxysilane (PFDS) molecules was used to anchor a second organic layer from mixed water-ethanol solution. The adsorption behavior and corrosion inhibition properties of the monolayer and also the bilayer were investigated by potentiodynamic polarization, scanning electron microscope (SEM), Fourier transformed infrared spectroscopy (FTIR) and contact angle measurements. Findings – The GPTMS/PFDS bilayer was successfully deposited onto the oxidized AISI 430SS surface. The optimal assembling time for the filming of the first GPTMS monolayer is 6 hours. Suitable values of pH and temperature of the PFDS self-assembly solution were pivotal to the successful deposition of the second layer. Compared to the GPTMS monolayer, the GPTMS/PFDS bilayer exhibited a significant enhancement of the corrosion inhibition performance of AISI 430SS in NaCl solution. Research limitations/implications – The contact angle value measured on the bilayer-modified surface was somewhat lower than the reported value of a complete fluorinated surface. However, further optimization of the assembling condition is needed to obtain more orderly and denser films. Originality/value – This paper provides useful information regarding the preparation of an organosilane bilayer on the surface of stainless steel and its corrosion inhibition properties in NaCl solution. It illustrates potential application prospects of GPTMS/PFDS bilayers for surface treatment of stainless steel.

THE ELECTROCHEMICAL STUDIES ON A SELF-ASSEMBLED VIOLOGEN MONOLAYER USING QUARTZ CRYSTAL MICROBALANCE

2002 ◽  
Vol 01 (05n06) ◽  
pp. 593-596 ◽  
Author(s):  
J. Y. OCK ◽  
H. K. SHIN ◽  
Y. S. KWON ◽  
S. H. SONG ◽  
S. M. CHANG ◽  
...  
Keyword(s):  
Self Assembly ◽  
Quartz Crystal ◽  
Surface Coverage ◽  
Gold Surface ◽  
Frequency Change ◽  
Self Assembled Monolayer ◽  
Solution Interface ◽  
Reversible Redox ◽  
Mass Detector ◽  
Self Assembled

The electrochemical behavior of viologen self-assembled monolayer has been investigated with QCM, which has been known as ng order mass detector. The self-assembly process of viologen was monitored using resonant frequency (ΔF) and resonant resistance (R). The QCM measurements indicated a mass adsorption for viologen assembling on the gold surface with a frequency change of about 300, 135 Hz and its surface coverage (Γ) was calculated to be 5.02 × 10-9 and 1.64 × 10-9 mol/cm2. A reversible redox process was also observed and analyzed with an ionic interaction at the viologen/solution interface using ΔF.

Formation of Antibody Microarrays on Aluminum Nitride Surface Using Patterned Organosilane Self-Assembled Monolayers

2009 ◽  
Vol 1202 ◽  
Author(s):  
Chi-Shun Chiu ◽  
Hong-Mao Lee ◽  
Shangjr Gwo
Keyword(s):  
Aluminum Nitride ◽  
Aluminum Gallium Nitride ◽  
Self Assembly ◽  
Fluorescent Protein ◽  
Specific Protein ◽  
Self Assembled Monolayer ◽  
Antibody Microarrays ◽  
Assembly Technique ◽  
Self Assembled ◽  
Lift Off

AbstractSurface biofunctionalization of group-III nitride semiconductors has recently attracted much interest due to their biocompatibility, nontoxicity, and long-term chemical stability under demanding physiochemical conditions for chemical and biological sensing. Among III-nitrides, aluminum nitride (AlN) and aluminum gallium nitride (AlGaN) are particularly important because they are often used as the sensing surfaces for sensors based on field-effect transistor or surface acoustic wave sensor structures. Patterned self-assembled monolayer (SAM) templates are composed of two types of organosilane molecules terminated with different functional groups (amino and methyl), which were fabricated on AlN/sapphire substrates by combining photolithography, lift-off process, and self-assembly technique. Clear imaging contrast of SAM micropatterns can be observed by field emission scanning electron microscopy (FE-SEM) operating at a low accelerating voltage in the range of 0.5–1.5 kV. In this work, the formation of green fluorescent protein (GFP) antibody microarrays was demonstrated by the specific protein binding of enhanced GFP (EGFP) labeling. The observed strong fluorescent signal from antibody functionalized regions on the SAM-patterned AlN surface indicates the retained biological activity of specific molecular recognition resulting from the antibody–EGFP interaction. The results reported here show that micropatterning of organosilane SAMs by the combination of photolithographic process and lift-off technique is a practical approach for the fabrication of reaction regions on AlN-based bioanalytical microdevices.

scholarly journals Construction and Characterizations of Antibacterial Surfaces Based on Self-Assembled Monolayer of Antimicrobial Peptides (Pac-525) Derivatives on Gold

Coatings ◽  
2021 ◽  
Vol 11 (9) ◽  
pp. 1014
Author(s):  
Zijiao Zhang ◽  
Ni Kou ◽  
Weilong Ye ◽  
Shuo Wang ◽  
Jiaju Lu ◽  
...  
Keyword(s):  
Antimicrobial Peptides ◽  
Self Assembly ◽  
The Self ◽  
Self Assembled Monolayer ◽  
E Coli ◽  
Antimicrobial Efficiency ◽  
Gold Substrates ◽  
Self Assembled ◽  
Antibacterial Surfaces

Background: Infection that is related to implanted biomaterials is a serious issue in the clinic. Antimicrobial peptides (AMPs) have been considered as an ideal alternative to traditional antibiotic drugs, for the treatment of infections, while some problems, such as aggregation and protein hydrolysis, are still the dominant concerns that compromise their antimicrobial efficiency in vivo. Methods: In this study, antimicrobial peptides underwent self-assembly on gold substrates, forming good antibacterial surfaces, with stable antibacterial behavior. The antimicrobial ability of AMPs grafted on the surfaces, with or without glycine spaces or a primer layer, was evaluated. Results: Specifically, three Pac-525 derivatives, namely, Ac-CGn-KWRRWVRWI-NH2 (n = 0, 2, or 6) were covalently grafted onto gold substrates via the self-assembling process for inhibiting the growth of Staphylococcus aureus (S. aureus) and Escherichia coli (E. coli). Furthermore, the alkanethiols HS(CH)10SH were firstly self-assembled into monolayers, as a primer layer (SAM-SH) for the secondary self-assembly of Pac-525 derivatives, to effectively enhance the bactericidal performance of the grafted AMPs. The -(CH)10-S-S-G6Pac derivative was highly effective against S. aureus and E. coli, and reduced the viable amount of E. coli and S. aureus to 0.4% and 33.2%, respectively, after 24 h of contact. In addition, the immobilized AMPs showed good biocompatibility, promoting bone marrow stem cell proliferation. Conclusion: the self-assembled monolayers of the Pac-525 derivatives have great potential as a novel therapeutic method for the treatment of implanted biomaterial infections.

Self-Assembly of Rod-Like Particles Into 2D Lattices

2008 ◽  
Author(s):  
M. Janjua ◽  
S. Nudurupati ◽  
I. Fischer ◽  
P. Singh ◽  
N. Aubry
Keyword(s):  
Electric Field ◽  
Self Assembly ◽  
Lateral Force ◽  
Spherical Particles ◽  
Fluid Interfaces ◽  
Electric Force ◽  
Fluid Interface ◽  
Self Assembled Monolayer ◽  
Approach Velocity ◽  
Self Assembled

It was recently shown by us that spherical particles floating on a fluid-fluid interface can be self-assembled, and the lattice between them can be controlled, using an electric field. In this paper we show that the technique can also be used to self assemble rod-like particles on fluid-fluid interfaces. The method consists of sprinkling particles at a liquid interface and applying an electric field normal to the interface, thus resulting in a combination of hydrodynamic (capillary) and electrostatic forces acting on the particles. A rod floating on the fluid interface experiences both a lateral force and a torque normal to the interface due to capillarity, and in the presence of an electric field, it is also subjected to an electric force and torque. The electric force affects the rods’ approach velocity and the torque aligns the rods parallel to each other. In the absence of an electric field, two rods that are initially more than one rod length away from each other come in contact so that they are either perpendicular or parallel to the line joining their centers, depending on their initial orientations. In the latter case, their ends are touching. Our experiments show that in an electric field of sufficiently large strength, only the latter arrangement is stable. Experiments also show that in this case the electric field causes the rods of the monolayer to align parallel to one another and that the lattice spacing of a self-assembled monolayer of rods increases.

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