scholarly journals Self-Assembled MoS2/ssDNA Nanostructures for the Capacitive Aptasensing of Acetamiprid Insecticide

2021 ◽  
Vol 11 (4) ◽  
pp. 1382 ◽  
Author(s):  
Maroua Hamami ◽  
Noureddine Raouafi ◽  
Hafsa Korri-Youssoufi
Keyword(s):  
Lipoic Acid ◽  
Dna Sequences ◽  
Electrochemical Impedance ◽  
Dna Aptamer ◽  
Covalent Attachment ◽  
Food Contaminants ◽  
Real Sample Analysis ◽  
Self Assembled ◽  
The Stability ◽  
Self Assembled Layer

The aim of this work is to detect acetamiprid using electrochemical capacitance spectroscopy, which is widely used as a pesticide in agriculture and is harmful to humans. We have designed aptasensing platform based on the adsorption of a DNA aptamer on lipoic acid-modified MoS2 nano-sheets. The biosensor takes advantage of the high affinity of single-stranded DNA sequences to MoS2 nano-sheets. The stability of DNA on MoS2 nano-sheets is assured by covalent attachment to lipoic acid that forms self-assembled layer on MoS2 surface. The biosensor exhibits excellent capacitance performances owing to its large effective surface area making it interesting material for capacitive transduction system. The impedance-derived capacitance varies with the increasing concentrations of acetamiprid that can be attributed to the aptamer desorption from the MoS2 nanosheets facilitating ion diffusion into MoS2 interlayers. The developed device showed high analytical performances for acetamiprid detection on electrochemical impedance spectroscopy EIS- derived capacitance variation and high selectivity toward the target in presence of other pesticides. Real sample analysis of food stuff such as tomatoes is demonstrated which open the way to their use for monitoring of food contaminants by tailoring the aptamer.

scholarly journals Study of the stability of self-assembled N-vinylcarbazole monolayers to protect copper against corrosion

2002 ◽  
Vol 67 (10) ◽  
pp. 685-696 ◽  
Author(s):  
Chun-Tao Wang ◽  
Shen-Hao Chen ◽  
Hou-Yi Ma ◽  
Lan Hua ◽  
Nai-Xing Wang
Keyword(s):  
Photoelectron Spectroscopy ◽  
Electrochemical Impedance ◽  
Self Assembled Monolayers ◽  
Copper Surfaces ◽  
Copper Electrodes ◽  
Adsorption Analysis ◽  
Assembled Monolayers ◽  
Self Assembled ◽  
The Stability ◽  
Electrochemical Impedance Spectroscopic

N-Vinylcarbazole (NVC) monolayers were self-assembled on copper surfaces. The electrochemical properties of the copper surfaces modified by NVC self-assembled monolayers (SAMs) were investigated using polarization and electrochemical impedance spectroscopic (EIS) methods. The polarization measurements indicated that the NVCSAMs could reduce the rates of the anodic and cathodic reaction on the surface of copper electrodes in 0.5 mol dm-3 NaCl solution. The EIS results showed the NVC formed a closely packed film that was able to inhibit copper corrosion. X-Ray photoelectron spectroscopy (XPS) analysis of the copper samples and atomic adsorption analysis of the solution showed that the copper surfaces were covered by NVCSAMs, and the adsorption of NVC on the copper surfaces was accompanied with dissolution of Cu into the solution.

scholarly journals Zn-Co-CeO2 vs. Zn-Co Coatings: Effect of CeO2 Sol in the Enhancement of the Corrosion Performance of Electrodeposited Composite Coatings

Metals ◽  
2021 ◽  
Vol 11 (5) ◽  
pp. 704
Author(s):  
Marija Riđošić ◽  
Nebojša D. Nikolić ◽  
Asier Salicio-Paz ◽  
Eva García-Lecina ◽  
Ljiljana S. Živković ◽  
...  
Keyword(s):  
Corrosion Resistance ◽  
Healing Rate ◽  
Electrochemical Impedance ◽  
Composite Coatings ◽  
Self Healing ◽  
Kelvin Probe ◽  
Artificial Defect ◽  
Volta Potential ◽  
Superior Corrosion Resistance ◽  
The Stability

Electrodeposition and characterization of novel ceria-doped Zn-Co composite coatings was the main goal of this research. Electrodeposited composite coatings were compared to pure Zn-Co coatings obtained under the same conditions. The effect of two ceria sources, powder and home-made sol, on the morphology and corrosion resistance of the composite coatings was determined. During the electrodeposition process the plating solution was successfully agitated in an ultrasound bath. The source of the particles was found to influence the stability and dispersity of plating solutions. The application of ceria sol resulted in an increase of the ceria content in the resulting coating and favored the refinement from cauliflower-like morphology (Zn-Co) to uniform and compact coral-like structure (Zn-Co-CeO2 sol). The corrosion resistance of the composite coatings was enhanced compared to bare Zn-Co as evidenced by electrochemical impedance spectroscopy and scanning Kelvin probe results. Zn-Co doped with ceria particles originating from ceria sol exhibited superior corrosion resistance compared to Zn-Co-CeO2 (powder) coatings. The self-healing rate of artificial defect was calculated based on measured Volta potential difference for which Zn-Co-CeO2 (sol) coatings exhibited a self-healing rate of 73.28% in a chloride-rich environment.

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.

scholarly journals Two-Dimensional Layered Oxide Structures Tailored by Self-Assembled Layer Stacking via Interfacial Strain

2016 ◽  
Vol 8 (26) ◽  
pp. 16845-16851 ◽  
Author(s):  
Wenrui Zhang ◽  
Mingtao Li ◽  
Aiping Chen ◽  
Leigang Li ◽  
Yuanyuan Zhu ◽  
...  
Keyword(s):  
Two Dimensional ◽  
Layered Oxide ◽  
Layer Stacking ◽  
Interfacial Strain ◽  
Self Assembled ◽  
Self Assembled Layer

scholarly journals An estimation on the mechanical stabilities of SAMs by low energy Ar+ cluster ion collision

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Y. Tong ◽  
G. R. Berdiyorov ◽  
A. Sinopoli ◽  
M. E. Madjet ◽  
V. A. Esaulov ◽  
...  
Keyword(s):  
Electron Irradiation ◽  
Photoelectron Spectroscopy ◽  
Density Functional ◽  
Crystal Surface ◽  
Depth Profiling ◽  
Low Energy ◽  
Cross Linking ◽  
Xps Spectra ◽  
Self Assembled ◽  
The Stability

AbstractThe stability of the molecular self-assembled monolayers (SAMs) is of vital importance to the performance of the molecular electronics and their integration to the future electronics devices. Here we study the effect of electron irradiation-induced cross-linking on the stability of self-assembled monolayer of aromatic 5,5′-bis(mercaptomethyl)-2,2′-bipyridine [BPD; HS-CH2-(C5H3N)2-CH2-SH] on Au (111) single crystal surface. As a refence, we also study the properties of SAMs of electron saturated 1-dodecanethiol [C12; CH3-(CH2)11-SH] molecules. The stability of the considered SAMs before and after electron-irradiation is studied using low energy Ar+ cluster depth profiling monitored by recording the X-ray photoelectron spectroscopy (XPS) core level spectra and the UV-photoelectron spectroscopy (UPS) in the valance band range. The results indicate a stronger mechanical stability of BPD SAMs than the C12 SAMs. The stability of BPD SAMs enhances further after electron irradiation due to intermolecular cross-linking, whereas the electron irradiation results in deterioration of C12 molecules due to the saturated nature of the molecules. The depth profiling time of the cross-linked BPD SAM is more than 4 and 8 times longer than the profiling time obtained for pristine and BPD and C12 SAMs, respectively. The UPS results are supported by density functional theory calculations, which show qualitative agreement with the experiment and enable us to interpret the features in the XPS spectra during the etching process for structural characterization. The obtained results offer helpful options to estimate the structural stability of SAMs which is a key factor for the fabrication of molecular devices.

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