The Experts below are selected from a list of 243 Experts worldwide ranked by ideXlab platform
Masoud Hatami - One of the best experts on this subject based on the ideXlab platform.
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ldh vb9 tio2 and ldh vb9 tio2 crosslinked pva nanocomposite prepared via facile and green technique and their photo degradation application for methylene blue dye under ultraviolet illumination
Applied Clay Science, 2018Co-Authors: Shadpour Mallakpour, Masoud HatamiAbstract:Abstract Vitamin B9 (VB9) as a Biological Molecule was used for the intercalation of MgAl-layered double hydroxide (LDH) which can increase the active sites and organic nature of LDH samples. Then, the LDH-VB9-TiO2 composite was synthesized with mass ratio of LDH-VB9:TiO2 equal to 1:1 through ultrasonic technique as a green and environmentally approach, and then the LDH-VB9-TiO2 was applied with three different mass ratios as organic-inorganic fillers in order to prepare in-situ crosslinked poly(vinyl alcohol) (CSPVA) nanocomposites (NC)s. The physio-chemical structure of CSPVA NCs was studied with variety of analyses such as FT-IR, XRD, FE-SEM, TEM and TGA. Finally, the prepared compounds were used for the photo-degradation of methylene blue (MB) dye from aqueous solution under ultraviolet lights. The photo-degradation performance of samples showed that the rate constant of Kapp was in the order of LDH-VB9-TiO2 > TiO2 > LDH-VB9/TiO2-CSPVA NC. Moreover, the value of half-life for degradation of MB dye was very remarkable for LDH-VB9-TiO2 sample (t1/2 = 81.53 min) in compared to the MB degradation without any photocatalyst sample (t1/2 = 6930 min). So, it can be concluded that the LDH-VB9 with nano-sheet structure has significant effect on the photo-degradation of MB dye in the presence TiO2. These kinds of NCs can be used as economy and environmentally friendly compounds in the industrial applications such as water purification.
Mahmoud Roushani - One of the best experts on this subject based on the ideXlab platform.
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using silver nanoparticle and thiol graphene quantum dots nanocomposite as a substratum to load antibody for detection of hepatitis c virus core antigen electrochemical oxidation of riboflavin was used as redox probe
Biosensors and Bioelectronics, 2017Co-Authors: Akram Valipour, Mahmoud RoushaniAbstract:Abstract In this study a facile green approach to employ silver nanoparticle (AgNPs) and thiol graphene quantum dots (GQD-SH) as the nanomaterial for ultrasensitive and selective detection of hepatitis C virus core antigen (HCV) have been investigated. AgNPs/GQD-SH was utilized as a substratum to load antibody for detection of hepatitis C virus core antigen. AgNPs have been immobilized on SH groups of GQDs via bonding formation of Ag-S and anti-HCV have been loaded on the electrode surface via the interaction between –NH 2 group of antibody and AgNPs. Using the proposed nanocomposite provides a specific platform with increased surface which is capable of loading more antibodies to entrap the antigen. The decreasing of the electrochemical signal can be achieved after the specific recognition between antibodies and antigens. Riboflavin was used as a Biological Molecule with inherent properties, for the first time, as the redox probe in the development of HCV core antigen electrochemical immunosensor. Compared to the other redox probes, riboflavin is superior in its oxidization in negative potential range, where the number of interfering species for riboflavin is much fewer. The proposed immunosensor showed wide linear range from 0.05 pg mL −1 to 60 ng mL −1 with limit of detection of 3 fg mL −1 . This novel immunosensor was used to analyze the serum sample. The immunosensor provides a convenient, low-cost and simple method for HCV core antigen detection and proposes new horizons for quantitative detection of antigen in the clinical diagnosis.
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designing an ultra sensitive aptasensor based on an agnps thiol gqd nanocomposite for tnt detection at femtomolar levels using the electrochemical oxidation of rutin as a redox probe
Biosensors and Bioelectronics, 2017Co-Authors: Faezeh Shahdostfard, Mahmoud RoushaniAbstract:In this paper, for the first time a highly sensitive and low-cost electrochemical aptasensor was fabricated based on a silver nanoparticles/thiol functionalized graphene quantum dot (AgNPs/thiol-GQD) nanocomposite for the measurement of 2,4,6-Trinitrotoluen (TNT) as a nitroaromatic explosive. For the first time Rutin (RU) as a Biological Molecule with inherent properties was used as the redox probe in the development of the TNT aptasensor was used. The system was based on a TNT-binding aptamer which is covalently attached onto the surface of a glassy carbon electrode (GCE) modified with the nanocomposite for the formation of a sensing layer and improving the performance of the aptasensor. Using the proposed nanocomposite provides a specific platform with increased surface area which is capable of loading more Aptamer (Ap) Molecules as a receptor element of TNT on the electrode surface. So, TNT Molecules is in an upward position to be measured and the obtained results indicate that the aptasensor exhibits two wide linear ranges and an unprecedented LOD compared with previously reported analytical methods for TNT detection. Applicability of the developed aptasensor to easily detect TNT in real samples was evaluated. It seems that the proposed strategy can be expanded to other nanoparticles and is expected to have promising implications in the design of electrochemical sensors or biosensors for the detection of various targets.
Shadpour Mallakpour - One of the best experts on this subject based on the ideXlab platform.
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ldh vb9 tio2 and ldh vb9 tio2 crosslinked pva nanocomposite prepared via facile and green technique and their photo degradation application for methylene blue dye under ultraviolet illumination
Applied Clay Science, 2018Co-Authors: Shadpour Mallakpour, Masoud HatamiAbstract:Abstract Vitamin B9 (VB9) as a Biological Molecule was used for the intercalation of MgAl-layered double hydroxide (LDH) which can increase the active sites and organic nature of LDH samples. Then, the LDH-VB9-TiO2 composite was synthesized with mass ratio of LDH-VB9:TiO2 equal to 1:1 through ultrasonic technique as a green and environmentally approach, and then the LDH-VB9-TiO2 was applied with three different mass ratios as organic-inorganic fillers in order to prepare in-situ crosslinked poly(vinyl alcohol) (CSPVA) nanocomposites (NC)s. The physio-chemical structure of CSPVA NCs was studied with variety of analyses such as FT-IR, XRD, FE-SEM, TEM and TGA. Finally, the prepared compounds were used for the photo-degradation of methylene blue (MB) dye from aqueous solution under ultraviolet lights. The photo-degradation performance of samples showed that the rate constant of Kapp was in the order of LDH-VB9-TiO2 > TiO2 > LDH-VB9/TiO2-CSPVA NC. Moreover, the value of half-life for degradation of MB dye was very remarkable for LDH-VB9-TiO2 sample (t1/2 = 81.53 min) in compared to the MB degradation without any photocatalyst sample (t1/2 = 6930 min). So, it can be concluded that the LDH-VB9 with nano-sheet structure has significant effect on the photo-degradation of MB dye in the presence TiO2. These kinds of NCs can be used as economy and environmentally friendly compounds in the industrial applications such as water purification.
Michael T Woodside - One of the best experts on this subject based on the ideXlab platform.
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measuring the average shape of transition paths during the folding of a single Biological Molecule
Proceedings of the National Academy of Sciences of the United States of America, 2019Co-Authors: Noel Q Hoffer, Krishna Neupane, Andrew G T Pyo, Michael T WoodsideAbstract:Transition paths represent the parts of a reaction where the energy barrier separating products and reactants is crossed. They are essential to understanding reaction mechanisms, yet many of their properties remain unstudied. Here, we report measurements of the average shape of transition paths, studying the folding of DNA hairpins as a model system for folding reactions. Individual transition paths were detected in the folding trajectories of hairpins with different sequences held under tension in optical tweezers, and path shapes were computed by averaging all transitions in the time domain, 〈 t ( x )〉, or by averaging transitions of a given duration in the extension domain, 〈 x ( t | τ )〉 τ . Whereas 〈 t ( x )〉 was close to straight, with only a subtle curvature, 〈 x ( t | τ )〉 τ had more pronounced curvature that fit well to theoretical expectations for the dominant transition path, returning diffusion coefficients similar to values obtained previously from independent methods. Simulations suggested that 〈 t ( x )〉 provided a less reliable representation of the path shape than 〈 x ( t | τ )〉 τ , because it was far more sensitive to the effects of coupling the Molecule to the experimental force probe. Intriguingly, the path shape variance was larger for some hairpins than others, indicating sequence-dependent changes in the diversity of transition paths reflective of differences in the character of the energy barriers, such as the width of the barrier saddle-point or the presence of parallel paths through multiple barriers between the folded and unfolded states. These studies of average path shapes point the way forward for probing the rich information contained in path shape fluctuations.
Joshua Salafsky - One of the best experts on this subject based on the ideXlab platform.
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second harmonic generation for studying structural motion of Biological Molecules in real time and space
Physical Chemistry Chemical Physics, 2007Co-Authors: Joshua SalafskyAbstract:SHG and sum-frequency generation (SFG) are surface-selective, nonlinear optical techniques whose ability to measure the average tilt angle of Molecules on surfaces is well known in non-Biological systems. By labeling Molecules with a second-harmonic-active dye probe, SHG detection is extended to any Biological Molecule. The method has been used in previous work to detect bioMolecules at an interface and their ligand-induced conformational changes. Here I demonstrate that SHG can be used to study structural motion quantitatively using a probe placed at a specific site (Cys-77) in adenylate kinase, a protein. The protein is also labeled non-site-specifically via amines. Labeled protein is absorbed to a surface and a baseline SH signal is measured. Upon introducing ATP, AMP or a specific inhibitor, AP5A, the baseline signal changes depending on the ligand and the labeling site. In particular, a substantial change in SH intensity is produced upon binding ATP to the amine-labeled protein, consistent with the X-ray crystal structures. In contrast, SHG polarization measurements are used to quantitatively determine that no rotation occurs at site Cys-77, in agreement with the lack of motion observed at this site in the X-ray crystal structures. A method for building a global map of conformational change in real time and space is proposed using a set of probes placed at different sites in a bioMolecule. For this purpose, SH-active unnatural amino acids are attractive complements to exogenous labels.