22 results on '"Aryl diazonium salt"'
Search Results
2. Air and moisture stable robust bio-polymeric palladium catalyzed C[sbnd]C bond formation and its application to the synthesis of fungicidal.
- Author
-
Chen, Ke, He, Guangzu, and Tang, Qiong
- Subjects
SUZUKI reaction ,PALLADIUM catalysts ,HETEROGENEOUS catalysts ,PALLADIUM ,DIAZONIUM compounds ,MOISTURE ,ARYL halides ,X-ray diffraction - Abstract
Cellulose supported bio-heterogeneous polymeric Pd(II) catalyst, stable to air and moisture, was designed and characterized with different spectroscopic techniques including FESEM, TEM, XPS, XRD, ICP-AES and EDX. The Pd(II) catalyst showed high catalytic performance (0.2 to 0.0009 mol%) to the Suzuki-Miyaura C C cross-coupling reaction of aromatic halides and aryl diazonium salts with a range of organoboronic acids to produce the respective biaryl product in up to 97% yield. Biologically active Boscalid, a fungicide that effectively inhibits the growth of fungal pathogens like ascomycetes on fruits and plants, could also be constructed through using this catalyst. Additionally, it was possible to recover the Pd(II) catalyst from the reaction medium and reused it repeatedly without significantly degrading its catalytic efficiency. [ABSTRACT FROM AUTHOR]
- Published
- 2023
- Full Text
- View/download PDF
3. Reduced Glutathione-Modified Electrode for the Detection of Hydroxyl Free Radicals.
- Author
-
Ghaedamini, Hamidreza, Duanghathaipornsuk, Surachet, Onusko, Patrick, Binsheheween, Abdullah M., and Kim, Dong-Shik
- Subjects
HYDROXYL group ,NICOTINAMIDE adenine dinucleotide phosphate ,FREE radicals ,GLUTATHIONE reductase ,CARBON electrodes ,REACTIVE oxygen species - Abstract
Hydroxyl radicals (•OH) are known as essential chemicals for cells to maintain their normal functions and defensive responses. However, a high concentration of •OH may cause oxidative stress-related diseases, such as cancer, inflammation, and cardiovascular disorders. Therefore, •OH can be used as a biomarker to detect the onset of these disorders at an early stage. Reduced glutathione (GSH), a well-known tripeptide for its antioxidant capacity against reactive oxygen species (ROS), was immobilized on a screen-printed carbon electrode (SPCE) to develop a real-time detection sensor with a high selectivity towards •OH. The signals produced by the interaction of the GSH-modified sensor and •OH were characterized using cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). The CV curve of the GSH-modified sensor in the Fenton reagent exhibited a pair of well-defined peaks, demonstrating the redox reaction of the electrochemical sensor and •OH. The sensor showed a linear relationship between the redox response and the concentration of •OH with a limit of detection (LOD) of 49 µM. Furthermore, using EIS studies, the proposed sensor demonstrated the capability of differentiating •OH from hydrogen peroxide (H
2 O2 ), a similar oxidizing chemical. After being immersed in the Fenton solution for 1 hr, redox peaks in the CV curve of the GSH-modified electrode disappeared, revealing that the immobilized GSH on the electrode was oxidized and turned to glutathione disulfide (GSSG). However, it was demonstrated that the oxidized GSH surface could be reversed back to the reduced state by reacting with a solution of glutathione reductase (GR) and nicotinamide adenine dinucleotide phosphate (NADPH), and possibly reused for •OH detection. [ABSTRACT FROM AUTHOR]- Published
- 2023
- Full Text
- View/download PDF
4. A novel ACE2-Based electrochemical biosensor for sensitive detection of SARS-CoV-2.
- Author
-
Ghaedamini, Hamidreza, Khalaf, Khalid, Kim, Dong-Shik, and Tang, Yuan
- Subjects
- *
SARS-CoV-2 , *DIAZONIUM compounds , *ANGIOTENSIN converting enzyme , *BIOSENSORS , *GOLD electrodes - Abstract
SARS-CoV-2 emerged in late 2019 and quickly spread globally, resulting in significant morbidity, mortality, and socio-economic disruptions. As of now, collaborative global efforts in vaccination and the advent of novel diagnostic tools have considerably curbed the spread and impact of the virus in many regions. Despite this progress, the demand remains for low-cost, accurate, rapid and scalable diagnostic tools to reduce the influence of SARS-CoV-2. Herein, the angiotensin-converting enzyme 2 (ACE2), a receptor for SARS-CoV-2, was immobilized on two types of electrodes, a screen-printed gold electrode (SPGE) and a screen-printed carbon electrode (SPCE), to develop electrochemical biosensors for detecting SARS-CoV-2 with high sensitivity and selectivity. This was achieved by using 1H, 1H, 2H, 2H-perfluorodecanethiol (PFDT) and aryl diazonium salt serving as linkers for SPGEs and SPCEs, respectively. Once SARS-CoV-2 was anchored onto the ACE2, the interaction of the virus with the redox probe was analyzed using electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV). Aryl diazonium salt was observed as a superior linker compared to PFDT due to its consistent performance in the modification of the SPCEs and effective ACE2 enzyme immobilization. A distinct pair of redox peaks in the cyclic voltammogram of the biosensor modified with aryl diazonium salt highlighted the redox reaction between the functional groups of SARS-CoV-2 and the redox probe. The sensor presented a linear relationship between the redox response and the logarithm of SARS-CoV-2 concentration, with a detection limit of 1.02 × 106 TCID50/mL (50% tissue culture infectious dose). Furthermore, the biosensor showed remarkable selectivity towards SARS-CoV-2 over H1N1virus. [Display omitted] • The electrochemical biosensors provide accurate SARS-CoV-2 detection using ACE2. • Aryl diazonium proves superior efficacy for ACE2 immobilization compared to PFDT. • The orientation of ACE2 on linkers significantly impacts the electron transfer rate. • The developed biosensor shows remarkable selectivity for SARS-CoV-2 over H1N1. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
5. Reduced Glutathione-Modified Electrode for the Detection of Hydroxyl Free Radicals
- Author
-
Hamidreza Ghaedamini, Surachet Duanghathaipornsuk, Patrick Onusko, Abdullah M. Binsheheween, and Dong-Shik Kim
- Subjects
hydroxyl radicals (•OH) ,reduced glutathione (GSH) ,aryl diazonium salt ,sensor regeneration ,cyclic voltammetry (CV) ,electrochemical impedance spectroscopy (EIS) ,Biotechnology ,TP248.13-248.65 - Abstract
Hydroxyl radicals (•OH) are known as essential chemicals for cells to maintain their normal functions and defensive responses. However, a high concentration of •OH may cause oxidative stress-related diseases, such as cancer, inflammation, and cardiovascular disorders. Therefore, •OH can be used as a biomarker to detect the onset of these disorders at an early stage. Reduced glutathione (GSH), a well-known tripeptide for its antioxidant capacity against reactive oxygen species (ROS), was immobilized on a screen-printed carbon electrode (SPCE) to develop a real-time detection sensor with a high selectivity towards •OH. The signals produced by the interaction of the GSH-modified sensor and •OH were characterized using cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). The CV curve of the GSH-modified sensor in the Fenton reagent exhibited a pair of well-defined peaks, demonstrating the redox reaction of the electrochemical sensor and •OH. The sensor showed a linear relationship between the redox response and the concentration of •OH with a limit of detection (LOD) of 49 µM. Furthermore, using EIS studies, the proposed sensor demonstrated the capability of differentiating •OH from hydrogen peroxide (H2O2), a similar oxidizing chemical. After being immersed in the Fenton solution for 1 hr, redox peaks in the CV curve of the GSH-modified electrode disappeared, revealing that the immobilized GSH on the electrode was oxidized and turned to glutathione disulfide (GSSG). However, it was demonstrated that the oxidized GSH surface could be reversed back to the reduced state by reacting with a solution of glutathione reductase (GR) and nicotinamide adenine dinucleotide phosphate (NADPH), and possibly reused for •OH detection.
- Published
- 2023
- Full Text
- View/download PDF
6. Tuning the Covering on Gold Surfaces by Grafting Amino-Aryl Films Functionalized with Fe(II) Phthalocyanine: Performance on the Electrocatalysis of Oxygen Reduction
- Author
-
Camila F. Olguín, Nicolás Agurto, Carlos P. Silva, Carolina P. Candia, Mireya Santander-Nelli, Juan Oyarzo, Alejandra Gómez, Juan F. Silva, and Jorge Pavez
- Subjects
grafting covering control ,aryl diazonium salt ,Fe(II) Phthalocyanine ,oxygen reduction reaction ,Organic chemistry ,QD241-441 - Abstract
Current selective modification methods, coupled with functionalization through organic or inorganic molecules, are crucial for designing and constructing custom-made molecular materials that act as electroactive interfaces. A versatile method for derivatizing surfaces is through an aryl diazonium salt reduction reaction (DSRR). A prominent feature of this strategy is that it can be carried out on various materials. Using the DSRR, we modified gold surface electrodes with 4-aminebenzene from 4-nitrobenzenediazonium tetrafluoroborate (NBTF), regulating the deposited mass of the aryl film to achieve covering control on the electrode surface. We got different degrees of covering: monolayer, intermediate, and multilayer. Afterwards, the ArNO2 end groups were electrochemically reduced to ArNH2 and functionalized with Fe(II)-Phthalocyanine to study the catalytic performance for the oxygen reduction reaction (ORR). The thickness of the electrode covering determines its response in front of ORR. Interestingly, the experimental results showed that an intermediate covering film presents a better electrocatalytic response for ORR, driving the reaction by a four-electron pathway.
- Published
- 2021
- Full Text
- View/download PDF
7. An electrochemical immunosensor for brain natriuretic peptide prepared with screen-printed carbon electrodes nanostructured with gold nanoparticles grafted through aryl diazonium salt chemistry.
- Author
-
Serafín, V., Torrente-Rodríguez, R.M., González-Cortés, A., Campuzano, S., Yáñez-Sedeño, P., Pingarrón, J.M., García de Frutos, P., and Sabaté, M.
- Subjects
- *
BRAIN natriuretic factor , *ELECTROCHEMICAL sensors , *GOLD nanoparticles , *NANOSTRUCTURED materials , *CARBON electrodes , *DIAZONIUM compounds - Abstract
A sensitive amperometric immunosensor has been prepared by immobilization of capture antibodies onto gold nanoparticles (AuNPs) grafted on a screen-printed carbon electrode (SPCE) through aryl diazonium salt chemistry using 4-aminothiophenol (AuNPs-S-Phe-SPCE). The immunosensor was designed for the accurate determination of clinically relevant levels of B-type natriuretic peptide (BNP) in human serum samples. The nanostructured electrochemical platform resulted in an ordered layer of AuNPs onto SPCEs which combined the advantages of high conductivity and improved stability of immobilized biomolecules. The resulting disposable immunosensor used a sandwich type immunoassay involving a peroxidase-labeled detector antibody. The amperometric transduction was carried out at −0.20 V (vs the Ag pseudo-reference electrode) upon the addition of hydroquinone (HQ) as electron transfer mediator and H 2 O 2 as the enzyme substrate. The nanostructured immunosensors show a storage stability of at least 25 days, a linear range between 0.014 and 15 ng mL −1 , and a LOD of 4 pg mL −1 , which is 100 times lower than the established cut-off value for heart failure (HF) diagnosis. The performance of the immunosensor is advantageously compared with that provided with immunosensors prepared by grafting SPCE with p-phenylendiamine (H 2 N-Phe-SPCE) and attaching AuNPs by immersion into an AuNPs suspension or by electrochemical deposition, as well as with immunosensors constructed using commercial AuNPs-modified SPCEs. The developed immunosensor was applied to the successful analysis of human serum from heart failure (HF) patients upon just a 10-times dilution as sample treatment. [ABSTRACT FROM AUTHOR]
- Published
- 2018
- Full Text
- View/download PDF
8. The copper-catalyzed cross-coupling reactions of aryl diazonium salts and isocyanides.
- Author
-
Li, Y., Cao, J., Zhu, Q., Zhang, X., and Shi, G.
- Subjects
- *
DIAZONIUM compounds , *ISOCYANIDES , *AROMATIC compounds , *ORGANIC compounds , *DIAZOTIZATION - Abstract
The copper-catalyzed cross-coupling reaction of aryl diazonium salts and isocyanides has been performed. This is a successful example of preparation of arylcarboxyamides with moderate to good yield under mild conditions. [ABSTRACT FROM AUTHOR]
- Published
- 2016
- Full Text
- View/download PDF
9. Spectroscopic Evidence for a Covalent Sigma Au-C Bond on Au Surfaces Using C-13 Isotope Labeling
- Author
-
Marcel Ceccato, Kim Daasbjerg, Nicolas Plumeré, Huaiguang Li, Kyoko Shimizu, Kopiec Gabriel Bruno, Frauke Nyßen, and Frank Müller
- Subjects
Materials science ,Au−C bond ,chemistry.chemical_element ,02 engineering and technology ,Au-C bond ,010402 general chemistry ,01 natural sciences ,Article ,CARBON ,symbols.namesake ,ELECTROCHEMICAL REDUCTION ,Magic angle spinning ,aryldiazonium salts ,isotope labeling ,GOLD ,MOLECULE ,QD1-999 ,ELECTRODE ,CONDUCTANCE ,SERS ,MONOLAYERS ,Nuclear magnetic resonance spectroscopy ,Carbon-13 NMR ,021001 nanoscience & nanotechnology ,ARYL DIAZONIUM SALT ,0104 chemical sciences ,Crystallography ,Chemistry ,Solid-state nuclear magnetic resonance ,chemistry ,Isotopic shift ,Covalent bond ,symbols ,solid-state NMR ,0210 nano-technology ,Raman spectroscopy ,Au nanoparticles ,Carbon - Abstract
The Au-C linkage has been demonstrated as a robust interface for coupling thin organic films on Au surfaces. However, the nature of the Au-C interaction remains elusive up to now. Surface-enhanced Raman spectroscopy was previously used to assign a band at 412 cm(-1) as a covalent sigma Au-C bond for films generated by spontaneous reduction of the 4-nitrobenzenediazonium salt on Au nanoparticles. However, this assignment is disputed based on our isotopic shift study. We now provide direct evidence for covalent Au-C bonds on the surface of Au nanoparticles using C-13 crosspolarization/magic angle spinning solid-state NMR spectroscopy combined with isotope substitution. A C-13 NMR shift at 165 ppm was identified as an aromatic carbon linked to the gold surface, while the shift at 148 ppm was attributed to C-C junctions in the arylated organic film. This demonstration of the covalent sigma Au-C bond fills the gap in metal-C bonds for organic films on surfaces, and it has great practical and theoretical significance in understanding and designing a molecular junction based on the Au-C bond.
- Published
- 2021
10. Tuning the Covering on Gold Surfaces by Grafting Amino-Aryl Films Functionalized with Fe(II) Phthalocyanine: Performance on the Electrocatalysis of Oxygen Reduction
- Author
-
Juan Oyarzo, Juan Silva, Alejandra Gómez, Camila F. Olguín, Carolina P. Candia, Jorge Pavez, Nicolás Agurto, Carlos P. Silva, and Mireya Santander-Nelli
- Subjects
Materials science ,Tetrafluoroborate ,aryl diazonium salt ,Pharmaceutical Science ,02 engineering and technology ,010402 general chemistry ,Electrocatalyst ,01 natural sciences ,Article ,Fe(II) phthalocyanine ,Analytical Chemistry ,Catalysis ,lcsh:QD241-441 ,chemistry.chemical_compound ,lcsh:Organic chemistry ,Drug Discovery ,Monolayer ,Physical and Theoretical Chemistry ,grafting covering control ,oxygen reduction reaction ,Aryl ,Organic Chemistry ,021001 nanoscience & nanotechnology ,0104 chemical sciences ,chemistry ,Chemical engineering ,Chemistry (miscellaneous) ,Electrode ,Phthalocyanine ,Molecular Medicine ,Surface modification ,0210 nano-technology - Abstract
Current selective modification methods, coupled with functionalization through organic or inorganic molecules, are crucial for designing and constructing custom-made molecular materials that act as electroactive interfaces. A versatile method for derivatizing surfaces is through an aryl diazonium salt reduction reaction (DSRR). A prominent feature of this strategy is that it can be carried out on various materials. Using the DSRR, we modified gold surface electrodes with 4-aminebenzene from 4-nitrobenzenediazonium tetrafluoroborate (NBTF), regulating the deposited mass of the aryl film to achieve covering control on the electrode surface. We got different degrees of covering: monolayer, intermediate, and multilayer. Afterwards, the ArNO2 end groups were electrochemically reduced to ArNH2 and functionalized with Fe(II)-Phthalocyanine to study the catalytic performance for the oxygen reduction reaction (ORR). The thickness of the electrode covering determines its response in front of ORR. Interestingly, the experimental results showed that an intermediate covering film presents a better electrocatalytic response for ORR, driving the reaction by a four-electron pathway.
- Published
- 2021
11. Insight into the covalent grafting of organic films onto carbon steel surfaces for protection.
- Author
-
Huo, Sheng-Juan, Chen, Li-Hong, Chu, Chen-Sheng, and Fang, Jian-Hui
- Subjects
- *
ORGANIC thin films , *CARBON steel , *SCANNING electron microscopy , *ACTIVATION energy , *SURFACE grafting (Polymer chemistry) , *TEMPERATURE effect , *CORROSION & anti-corrosives , *SOLUTION (Chemistry) - Abstract
The novel use of p-nitrophenyldiazonium tetrafluoroborate salt (GG salt) as a protectant that is electrochemically grafted onto carbon steel has been investigated in 0.05 mol L HSO and 5 wt% NaCl solutions using various corrosion monitoring techniques, such as electrochemical impedance spectroscopy, potentiodynamic polarisation, infrared spectra and scanning electron microscopy measurements. The electrochemical study reveals that this compound is a mixed inhibitor that predominantly controls the cathodic reaction. The surface-grafted film decreases the double-layer capacitance and obviously increases the charge transfer resistance relative to a bare carbon electrode. The values of inhibition effect remain nearly unchanged with an increase in temperature range of 298-318 K. The aryl diazonium is covalently bonded on the steel surface, causing a slight decrease in the apparent activation energy. Overall, the surface-grafted films exhibit excellent inhibition performance in acid and saline solutions within the studied temperature range. [ABSTRACT FROM AUTHOR]
- Published
- 2014
- Full Text
- View/download PDF
12. An electrochemical immunosensor for brain natriuretic peptide prepared with screen-printed carbon electrodes nanostructured with gold nanoparticles grafted through aryl diazonium salt chemistry
- Author
-
José M. Pingarrón, Susana Campuzano, Araceli González-Cortés, Verónica Serafín, M. Sabaté, P. García de Frutos, P. Yáñez-Sedeño, Rebeca M. Torrente-Rodríguez, Ministerio de Economía y Competitividad (España), Comunidad de Madrid, and European Commission
- Subjects
Immunoconjugates ,Metal Nanoparticles ,Biosensing Techniques ,Screen-printed electrodes ,02 engineering and technology ,AuNPs ,Electrochemistry ,01 natural sciences ,Antibodies ,Analytical Chemistry ,Aryl diazonium salt ,chemistry.chemical_compound ,Natriuretic Peptide, Brain ,Humans ,Sulfhydryl Compounds ,Electrodes ,Peroxidase ,Heart Failure ,Immunoassay ,chemistry.chemical_classification ,Aniline Compounds ,Chromatography ,Hydroquinone ,Aryl ,Biomolecule ,010401 analytical chemistry ,Human serum ,Diazonium Compounds ,Electrochemical Techniques ,Hydrogen Peroxide ,021001 nanoscience & nanotechnology ,Carbon ,Amperometry ,Hydroquinones ,Nanostructures ,0104 chemical sciences ,chemistry ,Linear range ,Colloidal gold ,Electrode ,Gold ,Sandwich immunosensor ,0210 nano-technology ,Biomarkers ,BNP - Abstract
A sensitive amperometric immunosensor has been prepared by immobilization of capture antibodies onto gold nanoparticles (AuNPs) grafted on a screen-printed carbon electrode (SPCE) through aryl diazonium salt chemistry using 4-aminothiophenol (AuNPs-S-Phe-SPCE). The immunosensor was designed for the accurate determination of clinically relevant levels of B-type natriuretic peptide (BNP) in human serum samples. The nanostructured electrochemical platform resulted in an ordered layer of AuNPs onto SPCEs which combined the advantages of high conductivity and improved stability of immobilized biomolecules. The resulting disposable immunosensor used a sandwich type immunoassay involving a peroxidase-labeled detector antibody. The amperometric transduction was carried out at −0.20 V (vs the Ag pseudo-reference electrode) upon the addition of hydroquinone (HQ) as electron transfer mediator and H2O2 as the enzyme substrate. The nanostructured immunosensors show a storage stability of at least 25 days, a linear range between 0.014 and 15 ng mL−1, and a LOD of 4 pg mL−1, which is 100 times lower than the established cut-off value for heart failure (HF) diagnosis. The performance of the immunosensor is advantageously compared with that provided with immunosensors prepared by grafting SPCE with p-phenylendiamine (H2N-Phe-SPCE) and attaching AuNPs by immersion into an AuNPs suspension or by electrochemical deposition, as well as with immunosensors constructed using commercial AuNPs-modified SPCEs. The developed immunosensor was applied to the successful analysis of human serum from heart failure (HF) patients upon just a 10-times dilution as sample treatment., The financial support of projects: RetosColaboración RTC-2015- 4184-1 (cofinanced by the Ministry of Economy and Competitivity and FEDER “una manera de hacer Europa”), CTQ2015-70023-R and CTQ2015-64402-C2-1-R (Spanish Ministry of Economy and Competitivity Research Projects) and S2013/MT-3029 (NANOAVANSENS Program from the Comunidad de Madrid) are gratefully acknowledged. R.M. Torrente-Rodríguez acknowledges a predoctoral contract from the Spanish Ministerio de Economía y Competitividad.
- Published
- 2018
13. Direct C-H Arylation of Quinones with Anilines.
- Author
-
Lamblin, Marc, Naturale, Guillaume, Dessolin, Jean, and Felpin, François-Xavier
- Subjects
- *
ARYLATION , *QUINONE , *ANILINE , *COUPLING reactions (Chemistry) , *BENZOQUINONES , *NITRITES , *DIAZONIUM compounds - Abstract
We discovered that anilines were suitable for the direct C-H arylation of benzoquinone in the presence of tert-butyl nitrite. This new reaction proceeds through the in situ formation of a diazonium hydroxide species. The coupling can be carried out at room temperature under neutral, additive-free, metal-free, and aqueous conditions, allowing an environmentally friendly procedure. [ABSTRACT FROM AUTHOR]
- Published
- 2012
- Full Text
- View/download PDF
14. Synthesis of indanones by sequential Heck-reduction–cyclization–alkylation (HRCA) reactions
- Author
-
Nassar-Hardy, Luma, Fabre, Sandy, Amer, Atef M., Fouquet, Eric, and Felpin, François-Xavier
- Subjects
- *
ORGANIC synthesis , *RING formation (Chemistry) , *HECK reaction , *METHODOLOGY , *CHEMICAL reduction , *TEMPERATURE effect - Abstract
Abstract: A simple and efficient synthesis of indanones, bearing a quaternary carbon centre, has been developed. The method features, in a one-pot process, the use of a multi-task palladium catalyst for the sequential Heck-reduction reactions, followed by a base-mediated cyclization–alkylation sequence. This methodology, called Heck-reduction–cyclization–alkylation (HRCA), is carried out under mild and simple experimental conditions with the use of inexpensive reagents. The mild conditions have been made possible by the use of diazonium salts that allow Heck couplings at moderate temperature (40°C) under ligand-free conditions. [Copyright &y& Elsevier]
- Published
- 2012
- Full Text
- View/download PDF
15. Noncovalent wrapping of chemically modified graphene with π-conjugated disk-like molecules.
- Author
-
Kamada, Shigenori, Nomoto, Hirotaka, Fukuda, Katsutoshi, Fukawa, Tadashi, Shirai, Hirofusa, and Kimura, Mutsumi
- Subjects
- *
GRAPHENE , *POLYCYCLIC aromatic hydrocarbons , *MULTILAYERED thin films , *THERMOGRAVIMETRY , *FLUORESCENCE - Abstract
facile and scalable preparation of dispersion of isolated graphene in various organic solvents has been developed by combining between covalent and noncovalent functionalizations of the graphene surface. Covalently functionalized graphene (FRG) was prepared by the reaction of partially reduced graphene oxide with aryl diazonium salts, followed by the graphene oxide being completely reduced with hydrazine. The resulting FRG disperse readily in organic solvents such as N, N′-dimethylformamide (DMF) and N-methyl-2-pyrrolidinone and the functionalization of graphene was characterized by Fourier transform infrared spectroscopy, thermogravimetric thermogram, X-ray photoelectron spectroscopy, and Raman spectroscopy. The hydrophobic surface of FRG was noncovalently wrapped with aromatic hexakis-dodecylhexa- peri-benzocorone (HBC) by simply mixing of dispersion of FRG in DMF with toluene solution of HBC. The complexation of FRG and HBC was monitored by viewing the absorption and fluorescence spectral changes. Atomic force microscopic images confirmed that graphene was covalently and noncovalently functionalized, while keeping a two-dimensional sheet shape. [Figure not available: see fulltext.] [ABSTRACT FROM AUTHOR]
- Published
- 2011
- Full Text
- View/download PDF
16. Horseradish peroxidase covalent grafting onto screen-printed carbon electrodes for levetiracetam chronoamperometric determination
- Author
-
Alonso-Lomillo, M. Asunción, Domínguez-Renedo, Olga, Hernández-Martín, Alba, and Arcos-Martínez, M. Julia
- Subjects
- *
PEROXIDASE , *HORSERADISH , *CARBON electrodes , *ANTICONVULSANTS , *ENZYMATIC analysis , *BIOSENSORS , *ELECTROCHEMICAL sensors , *IMMOBILIZED enzymes - Abstract
Abstract: A new enzymatic electrochemical biosensor based on disposable transducers, namely screen-printed carbon electrodes, has been developed for the determination of the antiepileptic drug levetiracetam. Horseradish peroxidase was immobilized onto the carbon working electrode previously modified by an aryl diazonium salt. The formation of amide bonds between the amino and carboxylic groups of the enzyme surface, catalyzed by hydroxysuccinimide and carbodiimide, leads to the electrode functionalization. This orientated enzymatic modification results in high reproducibility, with an associated relative standard deviation of 6.21% for the slopes of several calibration curves in the calibration range from 0.10 to 0.83mM. Experimental variables that can affect levetiracetam chronoamperometric response, such as hydrogen peroxide concentration, pH, and applied potential, were optimized to perform a selective determination. An average limit of detection of 1.75×10−5 M (α = β =0.05) was obtained. The biosensors were finally applied to the determination of levetiracetam in complex matrices such as pharmaceutical drugs, yielding successful results. [Copyright &y& Elsevier]
- Published
- 2009
- Full Text
- View/download PDF
17. Towards the fabrication of label-free amperometric immunosensors using SWNTs
- Author
-
Liu, Guozhen and Gooding, J. Justin
- Subjects
- *
CONDUCTOMETRIC analysis , *ELECTROCHEMISTRY , *SURFACE chemistry , *ELECTROCHEMICAL analysis , *ADSORPTION (Chemistry) , *BIOSENSORS , *CARBON nanotubes - Abstract
Abstract: A label-free immunosensor based on the modulation of the electrochemistry of a surface bound redox species, to detect the presence of antibodies, is demonstrated. In this proof of concept study the model epitope was biotin and the model antibody was anti-biotin IgG. Glassy carbon (GC) electrode surfaces were first modified with 4-nitrophenyl groups by electrochemical reductive adsorption of the corresponding aryl diazonium salt. Subsequently, the nitro group was reductively converted into an amine, giving 4-aminophenyl groups. Oxidatively shortened single walled carbon nanotubes (SWNTs) were then covalently attached to the electrode via self-assembly; a procedure that has previously been shown to give SWNTs aligned normal to the surface. 1,1-Di(aminomethyl)ferrocene was attached to the carboxylic acid terminated SWNTs followed by attachment of biotin to the remaining free amine of the ferrocene derivative. Binding of anti-biotin IgG to the surface bound epitope resulted in attenuation of the ferrocene electrochemistry. This label-free immunosensor was successfully able to detect anti-biotin between 30 and 450ngmL−1. [Copyright &y& Elsevier]
- Published
- 2009
- Full Text
- View/download PDF
18. Gomberg-Bachmann reaction
- Author
-
Li, Jie Jack and Li, Jie Jack
- Published
- 2003
- Full Text
- View/download PDF
19. An electrochemical immunosensor for brain natriuretic peptide prepared with screen-printed carbon electrodes nanostructured with gold nanoparticles grafted through aryl diazonium salt chemistry
- Author
-
Ministerio de Economía y Competitividad (España), Comunidad de Madrid, European Commission, Serafín, Verónica, Torrente-Rodríguez, Rebeca M., González-Cortés, Araceli, García de Frutos, Pablo, Sabaté, Manel, Campuzano, Susana, Yáñez-Sedeño, Pilar, Pingarrón, José Manuel, Ministerio de Economía y Competitividad (España), Comunidad de Madrid, European Commission, Serafín, Verónica, Torrente-Rodríguez, Rebeca M., González-Cortés, Araceli, García de Frutos, Pablo, Sabaté, Manel, Campuzano, Susana, Yáñez-Sedeño, Pilar, and Pingarrón, José Manuel
- Abstract
A sensitive amperometric immunosensor has been prepared by immobilization of capture antibodies onto gold nanoparticles (AuNPs) grafted on a screen-printed carbon electrode (SPCE) through aryl diazonium salt chemistry using 4-aminothiophenol (AuNPs-S-Phe-SPCE). The immunosensor was designed for the accurate determination of clinically relevant levels of B-type natriuretic peptide (BNP) in human serum samples. The nanostructured electrochemical platform resulted in an ordered layer of AuNPs onto SPCEs which combined the advantages of high conductivity and improved stability of immobilized biomolecules. The resulting disposable immunosensor used a sandwich type immunoassay involving a peroxidase-labeled detector antibody. The amperometric transduction was carried out at −0.20 V (vs the Ag pseudo-reference electrode) upon the addition of hydroquinone (HQ) as electron transfer mediator and H2O2 as the enzyme substrate. The nanostructured immunosensors show a storage stability of at least 25 days, a linear range between 0.014 and 15 ng mL−1, and a LOD of 4 pg mL−1, which is 100 times lower than the established cut-off value for heart failure (HF) diagnosis. The performance of the immunosensor is advantageously compared with that provided with immunosensors prepared by grafting SPCE with p-phenylendiamine (H2N-Phe-SPCE) and attaching AuNPs by immersion into an AuNPs suspension or by electrochemical deposition, as well as with immunosensors constructed using commercial AuNPs-modified SPCEs. The developed immunosensor was applied to the successful analysis of human serum from heart failure (HF) patients upon just a 10-times dilution as sample treatment.
- Published
- 2018
20. Tuning the Covering on Gold Surfaces by Grafting Amino-Aryl Films Functionalized with Fe(II) Phthalocyanine: Performance on the Electrocatalysis of Oxygen Reduction.
- Author
-
Olguín, Camila F., Agurto, Nicolás, Silva, Carlos P., Candia, Carolina P., Santander-Nelli, Mireya, Oyarzo, Juan, Gómez, Alejandra, Silva, Juan F., Pavez, Jorge, and Janczak, Jan
- Subjects
- *
OXYGEN reduction , *ELECTROCATALYSIS , *GOLD electrodes , *DIAZONIUM compounds , *GOLD , *TETRAFLUOROBORATES - Abstract
Current selective modification methods, coupled with functionalization through organic or inorganic molecules, are crucial for designing and constructing custom-made molecular materials that act as electroactive interfaces. A versatile method for derivatizing surfaces is through an aryl diazonium salt reduction reaction (DSRR). A prominent feature of this strategy is that it can be carried out on various materials. Using the DSRR, we modified gold surface electrodes with 4-aminebenzene from 4-nitrobenzenediazonium tetrafluoroborate (NBTF), regulating the deposited mass of the aryl film to achieve covering control on the electrode surface. We got different degrees of covering: monolayer, intermediate, and multilayer. Afterwards, the ArNO2 end groups were electrochemically reduced to ArNH2 and functionalized with Fe(II)-Phthalocyanine to study the catalytic performance for the oxygen reduction reaction (ORR). The thickness of the electrode covering determines its response in front of ORR. Interestingly, the experimental results showed that an intermediate covering film presents a better electrocatalytic response for ORR, driving the reaction by a four-electron pathway. [ABSTRACT FROM AUTHOR]
- Published
- 2021
- Full Text
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21. Electrochemical immunosensor for the determination of the cytokine interferon gamma (IFN-γ) in saliva.
- Author
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Sánchez-Tirado, E., González-Cortés, A., Yáñez-Sedeño, P., and Pingarrón, J.M.
- Subjects
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INTERFERON gamma , *SALIVA , *DIAZONIUM compounds , *INTERFERONS , *CARBON electrodes , *STREPTAVIDIN , *HYDROGEN peroxide - Abstract
A simple, fast and sensitive amperometric immunosensing method for the determination of the clinically relevant cytokine interferon gamma (IFN-γ) in saliva complying the requirements demanded for this kind of sample is reported. The target analyte was sandwiched between a specific capture antibody covalently immobilized on a screen-printed electrode functionalized by the diazonium salt grafting of p -aminobenzoic acid, and a biotinylated detector antibody labeled with a streptavidin-horseradish peroxidase conjugate. The amperometric responses measured at - 0.20 V vs Ag pseudo-reference electrode upon addition of hydrogen peroxide in the presence of hydroquinone as the redox mediator allowed a calibration plot with a linear range between 2.5 and 2000 pg mL−1 and a low limit of detection (1.6 pg mL−1) to be obtained. In addition, a good selectivity against other non-target proteins was achieved. The developed method was validated by analyzing a WHO 1st International Standard for IFN-γ. In addition, the immunosensor was used for the determination of the endogenous IFN-γ in saliva with results in excellent agreement with those obtained by a commercial ELISA kit. Image 1 • Sandwich immunosensor for interferon-γ. • Screen-printed carbon electrode modified by p -ABA electrochemical grafting. • Biotinylated detector antibody labeled with streptavidin-horseradish peroxidase. • Linear range between 2.5 and 2000 pg mL−1. • Accurate determination in saliva. [ABSTRACT FROM AUTHOR]
- Published
- 2020
- Full Text
- View/download PDF
22. Aromatic Substitution Reactions
- Author
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Carey, Francis A., Sundberg, Richard J., Carey, Francis A., and Sundberg, Richard J.
- Published
- 1977
- Full Text
- View/download PDF
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