The Experts below are selected from a list of 402 Experts worldwide ranked by ideXlab platform
Minh Chau Pham - One of the best experts on this subject based on the ideXlab platform.
-
selectivity and sensitivity of a reagentless electrochemical dna sensor studied by square wave voltammetry and fluorescence
Bioelectrochemistry, 2006Co-Authors: S Reisberg, Benoit Piro, Vincent Noel, Minh Chau PhamAbstract:Abstract Poly(5-hydroxy-1,4-naphthoquinone-co-5-hydroxy-3-Thioacetic Acid-1,4-naphthoquinone)-modified electrode is used for the direct electrochemical detection of oligonucleotide hybridization. The polymer film presents well-defined electroactivity in the cathodic potential domain (between 0 and − 0.8 V/SCE), due to the quinone group embedded into the polymer structure. The detection can be performed simply by square wave voltammetry. This sensor is a “signal-on” device and works with different oligonucleotide lengths, from 10 to 30 bases. Quantitative results from fluorescence are consistent with electrochemical data. It is confirmed that the signal increase in square wave voltammetry is unambiguously due to hybridization. The biosensor presents a detection limit of target of ca. 25 nM and is highly selective as it can discriminate single mismatch base.
-
direct electrochemical detection of oligonucleotide hybridization on poly 5 hydroxy 1 4 naphthoquinone co 5 hydroxy 3 Thioacetic Acid 1 4 naphthoquinone film
Analytical Chemistry, 2003Co-Authors: Minh Chau Pham, B Piro, L D Tran, T Ledoan, L H DaoAbstract:We describe the construction of a new DNA-modified electrode based on an electroactive film. 5-Hydroxy-1,4-naphthoquinone is coelectrooxidized with 5-hydroxy-3-Thioacetic Acid-1,4-naphthoquinone to give a copolymer, presenting both electroactive and chemically reactive groups. The carboxylic function acts as a precursor for the covalent grafting of ODN probes while the quinone group acts as the transduction element of hybridization. Electrochemical detection was performed by differential pulse voltammetry in the electroactivity domain of the quinone group (i.e., at very low potentials, 0 to −0.8 V vs SCE). A very clear modification of the redox activity is observed between unmodified and probe-modified films and especially upon addition of target ODN.
Emad Yousif - One of the best experts on this subject based on the ideXlab platform.
-
photochemical stability and photostabilizing efficiency of poly methyl methacrylate based on 2 Thioacetic Acid 5 phenyl 1 3 4 oxadiazole complexes
Arabian Journal of Chemistry, 2016Co-Authors: Emad Yousif, Jumat Salimon, Mustafa Abdalla, Ahmed Ahmed, Nadia SalihAbstract:Abstract The photostabilization of poly(methyl methacrylate) (PMMA) films by new types of 2-Thioacetic Acid-5-phenyl-1,3,4-oxadiazole with Sn(II), Ni(II), Zn(II), and Cu(II) complexes was investigated. The PMMA films containing concentration of complexes 0.5% by weight were produced by the casting method from chloroform solvent. The photostabilization activities of these compounds were determined by monitoring the hydroxyl index with irradiation time. The changes in viscosity average molecular weight of PMMA with irradiation time were also tracked (using benzene as a solvent). The quantum yield of the chain scission (Φcs) of these complexes in PMMA films was evaluated and found to range between 5.22 × 10−5 and 7.75 × 10−5. Results obtained showed that the rate of photostabilization of PMMA in the presence of the additive followed the trend: Ni ( L ) 2 > Ni ( L ) 2 > Zn ( L ) 2 > Sn ( L ) 2 According to the experimental results obtained, several mechanisms were suggested depending on the structure of the additive. Among them, UV absorption, peroxide decomposer and radical scavenger for photostabilizer mechanisms were suggested.
-
mechanism of photostabilization of poly methy methacrylate films by 2 Thioacetic Acid benzothiazol complexes
Arabian Journal of Chemistry, 2014Co-Authors: Emad Yousif, Jumat Salimon, Nadia SalihAbstract:Abstract The photostabilization of poly(methy methacrylate) (PMMA) films by 2-Thioacetic Acid benzothiazol with Sn(II), Cd(II), Ni(II), Zn(II) and Cu(II) complexes was investigated. The PMMA films containing concentration of complexes 0.5% by weight were produced by the casting method from chloroform solvent. The photostabilization activities of these compounds were determined by monitoring the hydroxyl index with irradiation time. The changes in viscosity-average molecular weight of PMMA with irradiation time were also tracked (using benzene as a solvent). The quantum yield of the chain scission (Φcs) of these complexes in PMMA films was evaluated and found to range between 3.64 × 10−5 and 7.44 × 10−5. Results obtained showed that the rate of photostabilization of PMMA in the presence of the additive followed the trend: Ni ( L ) 2 > Cu ( L ) 2 > Zn ( L ) 2 > Cd ( L ) 2 > Sn ( L ) 2 According to the experimental results obtained, several mechanisms were suggested depending on the structure of the additive. Among them UV absorption, peroxide decomposer and radical scavenger for photostabilizer additives mechanisms were suggested.
-
new stabilizers for polystyrene based on 2 Thioacetic Acid benzothiazol complexes
Journal of Applied Polymer Science, 2012Co-Authors: Emad Yousif, Jumat Salimon, Nadia SalihAbstract:The photostabilization of polystyrene (PS) films by 2-Thioacetic Acid benzothiazol with Sn(II), Cd(II), Ni(II), Zn(II), and Cu(II) complexes was investigated. The PS films containing complexes of concentration 0.5% by weight were produced by the casting method from chloroform solvent. The photostabilization activities of these compounds were determined by monitoring the carbonyl and hydroxyl indices with irradiation time. The changes in viscosimetric average molecular weight of PS with irradiation time were also tracked (using benzene as a solvent). The quantum yield of the chain scission (ϕcs) of these complexes in PS films was evaluated and found to range between 3.60 × 10−6 and 7.78 × 10−6. The results obtained showed that the rate of photostabilization of PS in the presence of the additive is in the following trend: Ni(L)2 > Cu(L)2 > Zn(L)2 > Cd(L)2 > Sn(L)2. According to the experimental results obtained, several mechanisms were suggested depending on the structure of the additive. Among UV absorption, peroxide decomposer and radical scavenger for photostabilizer additive mechanisms were suggested. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012
-
synthesis and characterization of transition metal complexes of 2 Thioacetic Acid benzothiazole ligand
Journal of Al-Nahrain University-Science, 2010Co-Authors: Ahmed Majeed, Emad Yousif, Yang Farina, Kebangsaan Malaysia Ukm Bangi Selangor D E MalaysiaAbstract:New metal complexes of the ligand 2-Thioacetic Acid benzothiazole with the metal ions Fe(III), Rh(III), Pd(II), Pt(IV) and Au(III) were prepared in alcoholic medium.The prepared complexes were characterized by FTIR Spectroscopy, electronic spectroscopy, elemental analysis, 1H NMR, 13C NMR, magnetic susceptibility and conductivity measurements. Molar ratio and continuous variation studies in solution gave comparable result with those obtained from solid state study. From the spectral measurements, monomer structures for the complexes were proposed.
-
complexes of 2 Thioacetic Acid benzothiazole with some metal ions
American Journal of Applied Sciences, 2009Co-Authors: Emad Yousif, Yang Farina, Khawla Kasar, Abdualbasit Graisa, Kumail AyidAbstract:New metal complexes of the ligand 2-Thioacetic Acid benzothiazole with the metal ions Ni(II), Cu(II), Zn(II), Cd(II) and Sn(II) were prepared in alcoholic medium. The prepared complexes were characterized by FTIR Spectroscopy, electronic spectroscopy, 1HNMR, 13CNMR, magnetic susceptibility and conductivity measurements. From the spectral measurements, monomer structures for the complexes were proposed. Square planar geometry was proposed for the copper complex. The other complexes were proposed to be tetrahedral.
L D Tran - One of the best experts on this subject based on the ideXlab platform.
-
reagentless amperometric detection of l lactate on an enzyme modified conducting copolymer poly 5 hydroxy 1 4 naphthoquinone co 5 hydroxy 3 Thioacetic Acid 1 4 naphthoquinone
Biosensors and Bioelectronics, 2004Co-Authors: J Haccoun, Benoit Piro, L D Tran, L A Dang, M C PhamAbstract:Abstract We have constructed a reagentless lactate sensor using lactate oxidase (LOD) covalently attached to an electropolymerized copolymer film, poly(5-hydroxy-1,4-naphthoquinone-co-5-hydroxy-3-Thioacetic Acid-1,4-naphthoquinone), poly(JUG-co-JUGA). Around 10−12 M cm−2 of covalently bound enzymes are immobilized on these films. In aerated medium, the amperometric response versus lactate concentration shows a sensitivity of 350±50 μA M−1 cm−2 for an applied potential of +0.5 V versus Ag|AgCl on a film-coated Pt electrode. In deaerated medium, the quinone group, conjugated with the polymer backbone, acts as an immobilized mediator. An amperometric response is observed on film-coated glassy carbon (GC) electrode at a potential as low as −0.1 V versus Ag|AgCl, with a sensitivity of 110±40 μA M−1 cm−2.
-
direct electrochemical detection of oligonucleotide hybridization on poly 5 hydroxy 1 4 naphthoquinone co 5 hydroxy 3 Thioacetic Acid 1 4 naphthoquinone film
Analytical Chemistry, 2003Co-Authors: Minh Chau Pham, B Piro, L D Tran, T Ledoan, L H DaoAbstract:We describe the construction of a new DNA-modified electrode based on an electroactive film. 5-Hydroxy-1,4-naphthoquinone is coelectrooxidized with 5-hydroxy-3-Thioacetic Acid-1,4-naphthoquinone to give a copolymer, presenting both electroactive and chemically reactive groups. The carboxylic function acts as a precursor for the covalent grafting of ODN probes while the quinone group acts as the transduction element of hybridization. Electrochemical detection was performed by differential pulse voltammetry in the electroactivity domain of the quinone group (i.e., at very low potentials, 0 to −0.8 V vs SCE). A very clear modification of the redox activity is observed between unmodified and probe-modified films and especially upon addition of target ODN.
Nadia Salih - One of the best experts on this subject based on the ideXlab platform.
-
photochemical stability and photostabilizing efficiency of poly methyl methacrylate based on 2 Thioacetic Acid 5 phenyl 1 3 4 oxadiazole complexes
Arabian Journal of Chemistry, 2016Co-Authors: Emad Yousif, Jumat Salimon, Mustafa Abdalla, Ahmed Ahmed, Nadia SalihAbstract:Abstract The photostabilization of poly(methyl methacrylate) (PMMA) films by new types of 2-Thioacetic Acid-5-phenyl-1,3,4-oxadiazole with Sn(II), Ni(II), Zn(II), and Cu(II) complexes was investigated. The PMMA films containing concentration of complexes 0.5% by weight were produced by the casting method from chloroform solvent. The photostabilization activities of these compounds were determined by monitoring the hydroxyl index with irradiation time. The changes in viscosity average molecular weight of PMMA with irradiation time were also tracked (using benzene as a solvent). The quantum yield of the chain scission (Φcs) of these complexes in PMMA films was evaluated and found to range between 5.22 × 10−5 and 7.75 × 10−5. Results obtained showed that the rate of photostabilization of PMMA in the presence of the additive followed the trend: Ni ( L ) 2 > Ni ( L ) 2 > Zn ( L ) 2 > Sn ( L ) 2 According to the experimental results obtained, several mechanisms were suggested depending on the structure of the additive. Among them, UV absorption, peroxide decomposer and radical scavenger for photostabilizer mechanisms were suggested.
-
mechanism of photostabilization of poly methy methacrylate films by 2 Thioacetic Acid benzothiazol complexes
Arabian Journal of Chemistry, 2014Co-Authors: Emad Yousif, Jumat Salimon, Nadia SalihAbstract:Abstract The photostabilization of poly(methy methacrylate) (PMMA) films by 2-Thioacetic Acid benzothiazol with Sn(II), Cd(II), Ni(II), Zn(II) and Cu(II) complexes was investigated. The PMMA films containing concentration of complexes 0.5% by weight were produced by the casting method from chloroform solvent. The photostabilization activities of these compounds were determined by monitoring the hydroxyl index with irradiation time. The changes in viscosity-average molecular weight of PMMA with irradiation time were also tracked (using benzene as a solvent). The quantum yield of the chain scission (Φcs) of these complexes in PMMA films was evaluated and found to range between 3.64 × 10−5 and 7.44 × 10−5. Results obtained showed that the rate of photostabilization of PMMA in the presence of the additive followed the trend: Ni ( L ) 2 > Cu ( L ) 2 > Zn ( L ) 2 > Cd ( L ) 2 > Sn ( L ) 2 According to the experimental results obtained, several mechanisms were suggested depending on the structure of the additive. Among them UV absorption, peroxide decomposer and radical scavenger for photostabilizer additives mechanisms were suggested.
-
new stabilizers for polystyrene based on 2 Thioacetic Acid benzothiazol complexes
Journal of Applied Polymer Science, 2012Co-Authors: Emad Yousif, Jumat Salimon, Nadia SalihAbstract:The photostabilization of polystyrene (PS) films by 2-Thioacetic Acid benzothiazol with Sn(II), Cd(II), Ni(II), Zn(II), and Cu(II) complexes was investigated. The PS films containing complexes of concentration 0.5% by weight were produced by the casting method from chloroform solvent. The photostabilization activities of these compounds were determined by monitoring the carbonyl and hydroxyl indices with irradiation time. The changes in viscosimetric average molecular weight of PS with irradiation time were also tracked (using benzene as a solvent). The quantum yield of the chain scission (ϕcs) of these complexes in PS films was evaluated and found to range between 3.60 × 10−6 and 7.78 × 10−6. The results obtained showed that the rate of photostabilization of PS in the presence of the additive is in the following trend: Ni(L)2 > Cu(L)2 > Zn(L)2 > Cd(L)2 > Sn(L)2. According to the experimental results obtained, several mechanisms were suggested depending on the structure of the additive. Among UV absorption, peroxide decomposer and radical scavenger for photostabilizer additive mechanisms were suggested. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012
L H Dao - One of the best experts on this subject based on the ideXlab platform.
-
direct electrochemical detection of oligonucleotide hybridization on poly 5 hydroxy 1 4 naphthoquinone co 5 hydroxy 3 Thioacetic Acid 1 4 naphthoquinone film
Analytical Chemistry, 2003Co-Authors: Minh Chau Pham, B Piro, L D Tran, T Ledoan, L H DaoAbstract:We describe the construction of a new DNA-modified electrode based on an electroactive film. 5-Hydroxy-1,4-naphthoquinone is coelectrooxidized with 5-hydroxy-3-Thioacetic Acid-1,4-naphthoquinone to give a copolymer, presenting both electroactive and chemically reactive groups. The carboxylic function acts as a precursor for the covalent grafting of ODN probes while the quinone group acts as the transduction element of hybridization. Electrochemical detection was performed by differential pulse voltammetry in the electroactivity domain of the quinone group (i.e., at very low potentials, 0 to −0.8 V vs SCE). A very clear modification of the redox activity is observed between unmodified and probe-modified films and especially upon addition of target ODN.
