scholarly journals Corrosion Protection of AA7075 Aluminium Alloy by Trimethoxy-Silanes Self-Assembled Monolayers

2013 ◽  
Vol 2013 ◽  
pp. 1-9 ◽  
Author(s):  
Rodrigo S. Neves ◽  
Daiane P. B. Silva ◽  
Artur J. Motheo
Keyword(s):  
Aluminium Alloy ◽  
Electrochemical Impedance ◽  
Protective Coatings ◽  
Reduction Reaction ◽  
Self Assembled Monolayers ◽  
Organic Monolayers ◽  
Assembled Monolayers ◽  
Self Assembled ◽  
Surface Modified ◽  
Trimethoxy Silane

This study presents electrochemical data concerning the aluminium alloy AA7075 surface modified by self-assembled monolayers (SAMs) of octadecyl-trimethoxy-silane and propyl-trimethoxy-silane. Polarisation curves have shown SAMs blocking effect, as they partially block the oxygen reduction reaction and displace the corrosion potential to positive values. Electrochemical impedance spectroscopy experiments have suggested that the protective effect comes from the oxide layer stabilization by the organic monolayers, which block the corroding species diffusion to the surface. These results show the potential of using methoxy-silanes SAMs as corrosion protective coatings; however, they are also indicative of the superior octadecyl-trimethoxy-silane protective characteristics.

scholarly journals Microfluidic Impedance Biosensor Chips Using Sensing Layers Based on DNA-Based Self-Assembled Monolayers for Label-Free Detection of Proteins

Biosensors ◽  
2021 ◽  
Vol 11 (3) ◽  
pp. 80
Author(s):  
Khaled Alsabbagh ◽  
Tim Hornung ◽  
Achim Voigt ◽  
Sahba Sadir ◽  
Taleieh Rajabi ◽  
...  
Keyword(s):  
Troponin I ◽  
Electrochemical Impedance ◽  
Specific Binding ◽  
Self Assembled Monolayers ◽  
Significant Shift ◽  
Label Free ◽  
Label Free Detection ◽  
Assembled Monolayers ◽  
Self Assembled ◽  
Biosensor Chip

A microfluidic chip for electrochemical impedance spectroscopy (EIS) is presented as bio-sensor for label-free detection of proteins by using the example of cardiac troponin I. Troponin I is one of the most specific diagnostic serum biomarkers for myocardial infarction. The microfluidic impedance biosensor chip presented here consists of a microscope glass slide serving as base plate, sputtered electrodes, and a polydimethylsiloxane (PDMS) microchannel. Electrode functionalization protocols were developed considering a possible charge transfer through the sensing layer, in addition to analyte-specific binding by corresponding antibodies and reduction of nonspecific protein adsorption to prevent false-positive signals. Reagents tested for self-assembled monolayers (SAMs) on gold electrodes included thiolated hydrocarbons and thiolated oligonucleotides, where SAMs based on the latter showed a better performance. The corresponding antibody was covalently coupled on the SAM using carbodiimide chemistry. Sampling and measurement took only a few minutes. Application of a human serum albumin (HSA) sample, 1000 ng/mL, led to negligible impedance changes, while application of a troponin I sample, 1 ng/mL, led to a significant shift in the Nyquist plot. The results are promising regarding specific detection of clinically relevant concentrations of biomarkers, such as cardiac markers, with the newly developed microfluidic impedance biosensor chip.

Controlling Area-Selective Atomic Layer Deposition of HfO2 Dielectric by Self-assembled Monolayers

2004 ◽  
Vol 811 ◽  
Author(s):  
Rong Chen ◽  
Hyoungsub Kim ◽  
Paul C. McIntyre ◽  
Stacey F. Bent
Keyword(s):  
Atomic Layer Deposition ◽  
Chain Length ◽  
Steric Effect ◽  
Atomic Layer ◽  
High Reactivity ◽  
Self Assembled Monolayers ◽  
Organic Monolayers ◽  
Layer Deposition ◽  
Assembled Monolayers ◽  
Self Assembled

ABSTRACTA series of self-assembled molecules have been investigated as deactivating agents for the HfO2 atomic layer deposition (ALD). Three important factors of self-assembled monolayers (SAMs) deactivating efficiency towards ALD--chain length, reactivity and steric effect--have been investigated and discussed as well as the initial blocking mechanism of this process. This investigation shows that in order to achieve satisfactory deactivation, it is crucial to choose high reactivity, low steric effect molecules with certain chain length to form condensed, high hydrophobic organic monolayers.

scholarly journals An impedance investigation of corrosion protection of copper by self-assembled monolayers of alkanethiols in aqueous solution

2004 ◽  
Vol 69 (10) ◽  
pp. 791-805 ◽  
Author(s):  
Guiyan Li ◽  
Houyi Ma ◽  
Yongli Jiao ◽  
Shrnhao Chen
Keyword(s):  
Equivalent Circuit ◽  
Corrosion Protection ◽  
Electrochemical Impedance ◽  
Copper Substrate ◽  
Self Assembled Monolayers ◽  
Copper Surfaces ◽  
Hydrophobic Barrier ◽  
Assembled Monolayers ◽  
Covered Electrodes ◽  
Self Assembled

Self-assembled monolayers (SAMs) of three n-alkanethiols, 1-octadecanethiol (C18SH), 1-dodecanethiol (C12SH), and 1-hexanethiol (C6SH), were formed on fresh, oxide- free copper surfaces obtained by HNO3 etching. The corrosion protection abilities of the three alkanethiol SAM s were evaluated in 0.2 mol cm-3 NaCl, 0.2 mol cm-3 HCl and 0.2 mol dm?3 H2SO4 solutions using the electrochemical impedance spectroscopy (EIS) method. The SAMs act as a hydrophobic barrier layer, which effectively prevents the copper substrate from contacting corrosive ions, thereby inhibiting corrosion of the copper to a considerable degree. A general equivalent circuit for the SAM-covered electrodes was proposed, bymeans of which the impedance behavior of the electrodes was interpreted and the corresponding electrochemical parameters were acquired. In addition, the quality of the SAMs and development of defects in the SAMs were also been evaluated based on the equivalent circuit. The dependence of the capacitance of the SAMs on the applied potentials was used to determine the stability of the SAMs at the applied potentials.

scholarly journals STM visualisation of counterions and the effect of charges on self-assembled monolayers of macrocycles

2011 ◽  
Vol 2 ◽  
pp. 674-680 ◽  
Author(s):  
Tibor Kudernac ◽  
Natalia Shabelina ◽  
Wael Mamdouh ◽  
Sigurd Höger ◽  
Steven De Feyter
Keyword(s):  
Self Assembly ◽  
The Self ◽  
Self Assembled Monolayers ◽  
Assembly Process ◽  
Organic Monolayers ◽  
Preferential Adsorption ◽  
Scanning Tunnelling ◽  
Assembled Monolayers ◽  
Tunnelling Microscopy ◽  
Self Assembled

Despite their importance in self-assembly processes, the influence of charged counterions on the geometry of self-assembled organic monolayers and their direct localisation within the monolayers has been given little attention. Recently, various examples of self-assembled monolayers composed of charged molecules on surfaces have been reported, but no effort has been made to prove the presence of counterions within the monolayer. Here we show that visualisation and exact localisation of counterions within self-assembled monolayers can be achieved with scanning tunnelling microscopy (STM). The presence of charges on the studied shape-persistent macrocycles is shown to have a profound effect on the self-assembly process at the liquid–solid interface. Furthermore, preferential adsorption was observed for the uncharged analogue of the macrocycle on a surface.

Mixed Self-Assembled Monolayers Modified Electrode for the Detection of Human Neutrophil Elastase

2014 ◽  
Vol 898 ◽  
pp. 308-311
Author(s):  
Wei Kun Li ◽  
Yu Jun Yang
Keyword(s):  
Neutrophil Elastase ◽  
Human Neutrophil ◽  
Electrochemical Impedance ◽  
Specific Inhibitor ◽  
Differential Pulse ◽  
Self Assembled Monolayers ◽  
Human Neutrophil Elastase ◽  
Redox Potentials ◽  
Assembled Monolayers ◽  
Self Assembled

A novel electrochemical sensor has been developed based on the specificity of the molecular recognition of human neutrophil elastase (HNE) provided by its specific inhibitor, sivelestat. First, the gold surfaces were modified with homogeneously mixed cysteamine and 6-ferrocenyl-1-hexanethiol (FcHT) to generate a mixed self-assembled monolayers (mSAM) modified Au electrode. Then the sivelestat was covalently attached to the mSAM by its carboxylic group to the amino group with the use of activating reagents: 1-ethyl-3(3-dimethylaminopropyl)-carbodiimide (EDC) and N-hydroxy-sulfosuccinimide (NHS). Cyclic voltammetry (CV), differential pulse voltammetry (DPV) and electrochemical impedance spectroscopy (EIS) was used to monitor the sensor assembly and the recognition of HNE on surfaces. Upon the selective binding of HNE to the surface bound sivelestat, the redox potentials of the ferrocene moiety of the mSAM shifted positively together with a decrease of the peak current. A clinically relevant range of HNE concentrations was successfully detected in pH 7.4 phosphate buffer.

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