diazonium salt
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Biosensors ◽  
2022 ◽  
Vol 12 (1) ◽  
pp. 39
Author(s):  
Elena A. Chiticaru ◽  
Luisa Pilan ◽  
Mariana Ioniţă

In this paper, we propose an improved electrochemical platform based on graphene for the detection of DNA hybridization. Commercial screen-printed carbon electrodes (SPCEs) were used for this purpose due to their ease of functionalization and miniaturization opportunities. SPCEs were modified with reduced graphene oxide (RGO), offering a suitable surface for further functionalization. Therefore, aryl-carboxyl groups were integrated onto RGO-modified electrodes by electrochemical reduction of the corresponding diazonium salt to provide enough reaction sites for the covalent immobilization of amino-modified DNA probes. Our final goal was to determine the optimum conditions needed to fabricate a simple, label-free RGO-based electrochemical platform to detect the hybridization between two complementary single-stranded DNA molecules. Each modification step in the fabrication process was monitored by cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) using [Fe(CN)6]3−/4− as a redox reporter. Although, the diazonium electrografted layer displayed the expected blocking effect of the charge transfer, the next steps in the modification procedure resulted in enhanced electron transfer properties of the electrode interface. We suggest that the improvement in the charge transfer after the DNA hybridization process could be exploited as a prospective sensing feature. The morphological and structural characterization of the modified electrodes performed by scanning electron microscopy (SEM) and Raman spectroscopy, respectively, were used to validate different modification steps in the platform fabrication process.


2022 ◽  
Vol 961 (1) ◽  
pp. 012020
Author(s):  
Haneen Majed Saheb ◽  
Elham Kadhim Hilal ◽  
Kasim Mohammed Hello

Abstract Using agrowaste as a source of recycled materials is a hot topic among experts and technologists these days. Waste materials can be converted into energy and new products by using them. As a rice waste, rice husk (RH) is a rich source of pure silica that is recyclable. The pure silica in RH was sulfonated by agitating and reacting it with diluted sulfuric acid. Various sulfate concentrations were loaded on silica (5, 10, 15, and 20%), andthe catalyst was designated as RHASO4. As the sulfate content increased, the specific surface area decreased. TEM analysis showed different forms of catalyst, including spherical, cylindrical, and fibbered forms. The catalyst was used for the in-situ generation of nitrose acid to prepare a diazonium salt for aromatic coupling reactions. Our experiment indicates that azo dyes can be produced at 68 percent over the catalyst at 10 degrees Celsius, while traditional catalysts cannot produce them above 5 degrees Celsius. For the highest yield of azo dyes, a 20% sulfate loading is optimum. A simple laboratory procedure is followed to reuse a catalyst without deteriorating its properties.


2021 ◽  
Author(s):  
Walid Sharmoukh ◽  
Meram S. Abdelrahman ◽  
Shaban Elkhabiry ◽  
Tawfik Khattab

Abstract A solid-state sensor was developed for the determination of copper ions (Cu2+) in aqueous media using tricyanofuranhydrazone as a spectroscopic probe and a paper sheet as the hosting strip. A new tricyanofuranhydrazone-based colorimetric chemosensor (TCFH) was synthesized for selective detection of Cu2+ in aqueous environments. The synthesis strategy of TCFH involved an azo-coupling process between the diazonium salt of 8-aminoquinoline and an active methyl-bearing tricyanofuran (TCF) heterocyclic moiety. The molecular structure of the prepared TCFH chemical sensor was verified with FT-IR, 1H and 13C NMR, as well as elemental analysis. Due to intramolecular charge transfer, TCFH chromophore demonstrated pronounced solvatochromism depending on the solvent polarity. Changes in both color and UV-vis absorption spectra demonstrated by the developed chemosensor proved that TCFH can be utilized to detect Cu2+ in the presence of other competing metallic cations and anions. The synthesized TCFH probe, which contains a hydrazone recognition moiety, demonstrates dramatic solvatochromic activity and high selectivity at the microlevel of copper ions with a color shift from yellow to purple. Mechanisms accounting for both metallochromic and solvatochromic activities were explored. Moreover, test strips of TCFH were successfully developed and applied for the detection of copper ions at different concentrations in aqueous media. The colorimetric properties of the prepared TCFH-immobilized paper strips were investigated by CIE Lab chromogenic parameters, colorimetric strength (K/S) and UV-Vis absorbance spectra. The metallochromic paper strip exhibited a detection limit at the ppm range. The best detection of Cu2+ was achieved in the pH range of 6.6-7.4 demonstrating an immediate color switch from yellow to purple relying on the total content of Cu2+. Scanning electron microscopy (SEM) was applied to characterize the deposition of tricyanofuranhydrazone onto the surface of the paper strip.


2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Dongmei Mo ◽  
Xiangying Li ◽  
Yong Chen ◽  
Yang Jiang ◽  
Chunfang Gan ◽  
...  

AbstractNanopesticide is one of the best pesticide formulation technologies to overcome the disadvantages of traditional pesticides, which has received great attention from the international community. Using high-speed emulsification and ultrasonic dispersion technology, an avermectin nano-delivery system (Av-NDs) with a particle size of 80–150 nm was prepared through embedding the pesticide molecule utilizing the cross-linking reaction between sodium lignosulfonate and p-phenylenediamine diazonium salt. The formulation and composition of Av-NDs were optimized, the morphology of Av-NDs was analyzed by scanning electron microscope, transmission electron microscope and dynamic light scattering, and the structure of Av-NDs was characterized by UV, IR and 1H NMR. Anti-photolysis and controlled-release tests show that the stability of Av-NDs is 3–4 times of the original avermectin (Av) and possesses the pH-responsive controlled release property. Furthermore, the insecticidal activity of Av-NDs is better than that of avermectin suspension concentrate (Av-SC). The Av-NDs with anti-photolysis and controlled-release characteristics is suitable for large-scale industrial production and is capable to be utilized as effective insecticide in the field.


2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Anna Malaika ◽  
Karolina Ptaszyńska ◽  
Mieczysław Kozłowski

AbstractEthylene was thermocatalytically transformed into carbon products via a CCVD process. The filamentous carbon obtained was further modified with concentrated sulfuric acid or 4‐benzenediazonium sulfonate (BDS) to produce acid-type catalysts. The as-prepared samples were characterized by SEM and TEM techniques to confirm their morphological features. TG, XRD, elemental, and porosity analyses were also performed to assess the quality of these materials. The fabricated carbons were tested in eco-friendly green synthesis of value-added fuel bio-additives, namely in glycerol esterification. The reaction of glycerol transformation was performed with acetic acid at 80 °C using different glycerol to acetic acid (Gly/AA) molar ratios. The samples functionalized with diazonium salt showed better performance in the above process than those modified with H2SO4, and this was found to be directly related to the degree of surface functionalization with acidic sites. BDS-modified carbon fibers allowed obtaining acceptable results within 6 h when the reaction was performed with a Gly/AA molar ratio of 1:6, however, the dominant products in this case were mono- and diacetins. Extended reaction time altered the distribution of products. Finally, the combined selectivity to the targeted acetins (i.e., DA and TA) was about 75.5%. A direct correlation between the content of –SO3H groups of CNFs and the yield of higher acetins was found.


Author(s):  
Ahmed Kandory ◽  
Anne-Marie Goncalves ◽  
Mathieu Frégnaux ◽  
Hélène Cattey ◽  
Badr Alaoui-Sossé ◽  
...  

2021 ◽  
Vol 21 (4) ◽  
pp. 912
Author(s):  
Bayader Fathil Abass ◽  
Taghreed Mohy Al-Deen Musa ◽  
Mahmoud Najim Aljibouri

The present paper demonstrates the synthesis and characterization of some transition elements complexes derived from (E)-7-hydroxy-6-((4-methoxyphenyl)diazenyl)-4-methyl-2H-chromen-2-one. The ligand was prepared in the general route of azo dyes by coupling the diazonium salt of 4-methoxyaniline with 4-methyl-7-hydroxycoumarin in sodium hydroxide 10% (w/v) solution. The azo ligand was identified on the basis of elemental analyses, MS, H-NMR and FT-IR spectra. The products of complexes with the new azo dye were isolated by the direct reactions of the metal chlorides of cadmium(II), zinc(II), vanadium(IV) and mercury(II) ions with the alkaline solution of free ligand to afford the colored in the following formulas, complexes[ML2]2H2O formula, M=Cd(II) and Zn(II). However the vanadium(IV) complex was square pyramid in [VOL2]SO42H2O chemical formula. As well as the tetrahedral environment was suggested for mercury(II) complex in formula [HgL2]. The time and mole ratio factors were studied to obtain the optimized conditions of metal complexes formations and the observed data investigated the deprotonation of the azo-dye at pH to range (7–7.5) with 30 min as time of reaction to get pure metal chelates. The TG-DSC study confirmed the thermal stability of complexes at a wide range of average heating in inert gas of analysis and the results observed from loss weight percent investigated the proposed structures of the prepared metal complexes.


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