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Mehmet Lutfi Yola - One of the best experts on this subject based on the ideXlab platform.
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a novel dna biosensor based on a pencil graphite electrode modified with polypyrrole functionalized multiwalled carbon nanotubes for determination of 6 mercaptopurine anticancer drug
Industrial & Engineering Chemistry Research, 2015Co-Authors: Hassan Karimimaleh, Mehmet Lutfi Yola, Necip Atar, Vinod Kumar Gupta, Fahimeh Tahernejadjavazmi, Ali A EnsafiAbstract:A novel and sensitive biosensor employing immobilized DNA on a pencil graphite electrode modified with polypyrrole/functionalized multiwalled carbon nanotubes for the determination of 6-mercaptopurine (6-MP) is presented. In the first step, we modified the pencil graphite surface with polypyrrole and functionalized multiwalled carbon nanotubes (MWCNT/COOH). The developed electrode was characterized by scanning electron microscopy, atomic force microscopy, reflection–absorption Infrared Spectroscopy, X-ray photoelectron Spectroscopy, and electrochemical impedance Spectroscopy. In the other step, we used decreases in the oxidation responses of guanine and adenine as a sign of the interaction of 6-MP with salmon sperm double-stranded DNA using differential pulse voltammetry. The signal of guanine oxidation was linear with respect to the 6-MP concentration in the range of 0.2–100 μmol L–1 with a detection limit of 0.08 μmol L–1. The modified electrode was utilized for the determination of 6-MP in real samples.
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a sensitive molecular imprinted electrochemical sensor based on gold nanoparticles decorated graphene oxide application to selective determination of tyrosine in milk
Sensors and Actuators B-chemical, 2015Co-Authors: Mehmet Lutfi Yola, Tanju Eren, Necip AtarAbstract:Abstract In present study, a sensitive imprinted electrochemical sensor based on cubic gold nanoparticles (cAuNPs) involved in 2-aminoethanethiol (2-AET) functionalized graphene oxide (GO) modified glassy carbon (GC) electrode was developed for determination of tyrosine (Tyr). The prepared nanomaterials were characterized by using scanning electron microscope (SEM), transmission electron microscope (TEM), X-ray photoelectron Spectroscopy (XPS) and reflection–absorption Infrared Spectroscopy (RAIRS). Tyr imprinted film was constructed by cyclic voltammetry (CV) for 20 cycles in the presence of 80 mM phenol in phosphate buffer solution (pH 7.0) containing 20 mM Tyr. The imprinted electrochemical sensor was validated according to the ICH guideline and found to be linear, sensitive, precise and accurate. The linearity range and the detection limit were obtained as 1.0 × 10−9 to 2.0 × 10−8 M and 1.5 × 10−10 M, respectively. The developed imprinted sensor was successfully applied to milk samples. In addition, the stability and reproducibility of the prepared molecular imprinted electrode were investigated. The excellent long-term stability and reproducibility of the prepared Tyr imprinted electrodes make them attractive in electrochemical sensors.
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molecularly imprinted electrochemical biosensor based on fe au nanoparticles involved in 2 aminoethanethiol functionalized multi walled carbon nanotubes for sensitive determination of cefexime in human plasma
Biosensors and Bioelectronics, 2014Co-Authors: Mehmet Lutfi Yola, Tanju Eren, Necip AtarAbstract:Abstract The molecular imprinting technique depends on the molecular recognition. It is a polymerization method around the target molecule. Hence, this technique creates specific cavities in the cross-linked polymeric matrices. In present study, a sensitive imprinted electrochemical biosensor based on Fe@Au nanoparticles (Fe@AuNPs) involved in 2-aminoethanethiol (2-AET) functionalized multi-walled carbon nanotubes (f-MWCNs) modified glassy carbon (GC) electrode was developed for determination of cefexime (CEF). The results of X-ray photoelectron Spectroscopy (XPS) and Reflection-Absorption Infrared Spectroscopy (RAIRS) confirmed the formation of the developed surfaces. CEF imprinted film was constructed by cyclic voltammetry (CV) for 9 cycles in the presence of 80 mM pyrrole in phosphate buffer solution (pH 6.0) containing 20 mM CEF. The developed electrochemical biosensor was validated according to the International Conference on Harmonisation (ICH) guideline and found to be linear, sensitive, selective, precise and accurate. The linearity range and the detection limit were obtained as 1.0×10 −10 –1.0×10 −8 M and 2.2×10 −11 M, respectively. The developed CEF imprinted sensor was successfully applied to real samples such as human plasma. In addition, the stability and reproducibility of the prepared molecular imprinted electrode were investigated. The excellent long-term stability and reproducibility of the prepared CEF imprinted electrodes make them attractive in electrochemical sensors.
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a novel electro analytical nanosensor based on graphene oxide silver nanoparticles for simultaneous determination of quercetin and morin
Electrochimica Acta, 2014Co-Authors: Mehmet Lutfi Yola, Tanju Eren, Vinod Kumar Gupta, Necip AtarAbstract:Abstract In this report, silver nanoparticles (AgNPs) with the mean diameters of 10-30 nm were self-assembled onto the surfaces of 2-aminoethanethiol (2-AET) functionalized graphene oxide (AETGO) sheets. The graphene oxide (GO) and AgNPs-AETGO nanocomposites were characterized by a transmission electron microscope (TEM), x-ray photoelectron Spectroscopy (XPS), reflection–absorption Infrared Spectroscopy (RAIRS) and the x-ray diffraction (XRD). The simultaneous determination of quercetin (QR) and morin (MR) has been performed on glassy carbon electrode (GCE) modified with AgNPs-AETGO (AgNPs-AETGO/GCE). QR presented an oxidation step at Ea of 200 mV and reduction step at Ec of 150 mV and RT presented an oxidation step at Ea of 600 mV at AgNPs-AETGO/GCE by cyclic voltammetry (CV). The linearity ranges and the detection limits of QR and MR were 1.0 × 10-8 - 5.0 × 10-6 M and 3.3 × 10-9 M, respectively. The AgNPs-AETGO/GCE was also applied to real samples for the simultaneous determination of QR and MR. Thus the developed method can be adopted as an alternative to the published chromatographic, spectrophotometric and electroanalytical methods for simultaneous determination of QR and MR.
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a novel voltammetric sensor based on gold nanoparticles involved in p aminothiophenol functionalized multi walled carbon nanotubes application to the simultaneous determination of quercetin and rutin
Electrochimica Acta, 2014Co-Authors: Mehmet Lutfi Yola, Necip AtarAbstract:Abstract Carbon nanotubes are expected to play a significant role in the design and manufacture of many nano-material devices in the future. Carbon nanotubes exhibit many unique properties which generate strong interests in studying their applications. In addition, certain properties of gold nanoparticles (e.g., conductivity, catalytic and photocatalytic activity) suggest that gold-nanoparticle-functionalized carbon nanotubes may prove applicable in future fabrication of nanodevices. In this study, gold nanoparticles (AuNPs) with the mean diameters of 20-25 nm were self-assembled onto the surfaces of p-aminothiophenol functionalized multi-walled carbon nanotubes (p-MWCNs) sheets. The p-MWCNs and AuNPs/p-MWCNs nanocomposites were characterized by reflection–absorption Infrared Spectroscopy (RAIRS), transmission electron microscope (TEM), x-ray photoelectron Spectroscopy (XPS), electrochemical impedance Spectroscopy (EIS) and x-ray diffraction (XRD) method. The simultaneous determination of quercetin (QR) and rutin (RT) was performed by square wave voltammetry (SWV) on glassy carbon electrode (GCE) modified with AuNPs/p-MWCNs nanocomposite (AuNPs/p-MWCNs-GCE). QR presented two oxidation steps at E a1 of 270 mV and E a2 of 450 mV and RT presented only one oxidation step at E a of 360 mV at AuNPs/p-MWCNs-GCE. The linearity ranges and the detection limits of QR and RT were 1.0 × 10 −9 - 5.0 × 10 −8 M and 3.3 × 10 −10 . The application of the prepared nanocomposite to the analysis of real sample was also investigated.
Necip Atar - One of the best experts on this subject based on the ideXlab platform.
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a novel dna biosensor based on a pencil graphite electrode modified with polypyrrole functionalized multiwalled carbon nanotubes for determination of 6 mercaptopurine anticancer drug
Industrial & Engineering Chemistry Research, 2015Co-Authors: Hassan Karimimaleh, Mehmet Lutfi Yola, Necip Atar, Vinod Kumar Gupta, Fahimeh Tahernejadjavazmi, Ali A EnsafiAbstract:A novel and sensitive biosensor employing immobilized DNA on a pencil graphite electrode modified with polypyrrole/functionalized multiwalled carbon nanotubes for the determination of 6-mercaptopurine (6-MP) is presented. In the first step, we modified the pencil graphite surface with polypyrrole and functionalized multiwalled carbon nanotubes (MWCNT/COOH). The developed electrode was characterized by scanning electron microscopy, atomic force microscopy, reflection–absorption Infrared Spectroscopy, X-ray photoelectron Spectroscopy, and electrochemical impedance Spectroscopy. In the other step, we used decreases in the oxidation responses of guanine and adenine as a sign of the interaction of 6-MP with salmon sperm double-stranded DNA using differential pulse voltammetry. The signal of guanine oxidation was linear with respect to the 6-MP concentration in the range of 0.2–100 μmol L–1 with a detection limit of 0.08 μmol L–1. The modified electrode was utilized for the determination of 6-MP in real samples.
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a sensitive molecular imprinted electrochemical sensor based on gold nanoparticles decorated graphene oxide application to selective determination of tyrosine in milk
Sensors and Actuators B-chemical, 2015Co-Authors: Mehmet Lutfi Yola, Tanju Eren, Necip AtarAbstract:Abstract In present study, a sensitive imprinted electrochemical sensor based on cubic gold nanoparticles (cAuNPs) involved in 2-aminoethanethiol (2-AET) functionalized graphene oxide (GO) modified glassy carbon (GC) electrode was developed for determination of tyrosine (Tyr). The prepared nanomaterials were characterized by using scanning electron microscope (SEM), transmission electron microscope (TEM), X-ray photoelectron Spectroscopy (XPS) and reflection–absorption Infrared Spectroscopy (RAIRS). Tyr imprinted film was constructed by cyclic voltammetry (CV) for 20 cycles in the presence of 80 mM phenol in phosphate buffer solution (pH 7.0) containing 20 mM Tyr. The imprinted electrochemical sensor was validated according to the ICH guideline and found to be linear, sensitive, precise and accurate. The linearity range and the detection limit were obtained as 1.0 × 10−9 to 2.0 × 10−8 M and 1.5 × 10−10 M, respectively. The developed imprinted sensor was successfully applied to milk samples. In addition, the stability and reproducibility of the prepared molecular imprinted electrode were investigated. The excellent long-term stability and reproducibility of the prepared Tyr imprinted electrodes make them attractive in electrochemical sensors.
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molecularly imprinted electrochemical biosensor based on fe au nanoparticles involved in 2 aminoethanethiol functionalized multi walled carbon nanotubes for sensitive determination of cefexime in human plasma
Biosensors and Bioelectronics, 2014Co-Authors: Mehmet Lutfi Yola, Tanju Eren, Necip AtarAbstract:Abstract The molecular imprinting technique depends on the molecular recognition. It is a polymerization method around the target molecule. Hence, this technique creates specific cavities in the cross-linked polymeric matrices. In present study, a sensitive imprinted electrochemical biosensor based on Fe@Au nanoparticles (Fe@AuNPs) involved in 2-aminoethanethiol (2-AET) functionalized multi-walled carbon nanotubes (f-MWCNs) modified glassy carbon (GC) electrode was developed for determination of cefexime (CEF). The results of X-ray photoelectron Spectroscopy (XPS) and Reflection-Absorption Infrared Spectroscopy (RAIRS) confirmed the formation of the developed surfaces. CEF imprinted film was constructed by cyclic voltammetry (CV) for 9 cycles in the presence of 80 mM pyrrole in phosphate buffer solution (pH 6.0) containing 20 mM CEF. The developed electrochemical biosensor was validated according to the International Conference on Harmonisation (ICH) guideline and found to be linear, sensitive, selective, precise and accurate. The linearity range and the detection limit were obtained as 1.0×10 −10 –1.0×10 −8 M and 2.2×10 −11 M, respectively. The developed CEF imprinted sensor was successfully applied to real samples such as human plasma. In addition, the stability and reproducibility of the prepared molecular imprinted electrode were investigated. The excellent long-term stability and reproducibility of the prepared CEF imprinted electrodes make them attractive in electrochemical sensors.
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a novel electro analytical nanosensor based on graphene oxide silver nanoparticles for simultaneous determination of quercetin and morin
Electrochimica Acta, 2014Co-Authors: Mehmet Lutfi Yola, Tanju Eren, Vinod Kumar Gupta, Necip AtarAbstract:Abstract In this report, silver nanoparticles (AgNPs) with the mean diameters of 10-30 nm were self-assembled onto the surfaces of 2-aminoethanethiol (2-AET) functionalized graphene oxide (AETGO) sheets. The graphene oxide (GO) and AgNPs-AETGO nanocomposites were characterized by a transmission electron microscope (TEM), x-ray photoelectron Spectroscopy (XPS), reflection–absorption Infrared Spectroscopy (RAIRS) and the x-ray diffraction (XRD). The simultaneous determination of quercetin (QR) and morin (MR) has been performed on glassy carbon electrode (GCE) modified with AgNPs-AETGO (AgNPs-AETGO/GCE). QR presented an oxidation step at Ea of 200 mV and reduction step at Ec of 150 mV and RT presented an oxidation step at Ea of 600 mV at AgNPs-AETGO/GCE by cyclic voltammetry (CV). The linearity ranges and the detection limits of QR and MR were 1.0 × 10-8 - 5.0 × 10-6 M and 3.3 × 10-9 M, respectively. The AgNPs-AETGO/GCE was also applied to real samples for the simultaneous determination of QR and MR. Thus the developed method can be adopted as an alternative to the published chromatographic, spectrophotometric and electroanalytical methods for simultaneous determination of QR and MR.
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a novel voltammetric sensor based on gold nanoparticles involved in p aminothiophenol functionalized multi walled carbon nanotubes application to the simultaneous determination of quercetin and rutin
Electrochimica Acta, 2014Co-Authors: Mehmet Lutfi Yola, Necip AtarAbstract:Abstract Carbon nanotubes are expected to play a significant role in the design and manufacture of many nano-material devices in the future. Carbon nanotubes exhibit many unique properties which generate strong interests in studying their applications. In addition, certain properties of gold nanoparticles (e.g., conductivity, catalytic and photocatalytic activity) suggest that gold-nanoparticle-functionalized carbon nanotubes may prove applicable in future fabrication of nanodevices. In this study, gold nanoparticles (AuNPs) with the mean diameters of 20-25 nm were self-assembled onto the surfaces of p-aminothiophenol functionalized multi-walled carbon nanotubes (p-MWCNs) sheets. The p-MWCNs and AuNPs/p-MWCNs nanocomposites were characterized by reflection–absorption Infrared Spectroscopy (RAIRS), transmission electron microscope (TEM), x-ray photoelectron Spectroscopy (XPS), electrochemical impedance Spectroscopy (EIS) and x-ray diffraction (XRD) method. The simultaneous determination of quercetin (QR) and rutin (RT) was performed by square wave voltammetry (SWV) on glassy carbon electrode (GCE) modified with AuNPs/p-MWCNs nanocomposite (AuNPs/p-MWCNs-GCE). QR presented two oxidation steps at E a1 of 270 mV and E a2 of 450 mV and RT presented only one oxidation step at E a of 360 mV at AuNPs/p-MWCNs-GCE. The linearity ranges and the detection limits of QR and RT were 1.0 × 10 −9 - 5.0 × 10 −8 M and 3.3 × 10 −10 . The application of the prepared nanocomposite to the analysis of real sample was also investigated.
Heon Kang - One of the best experts on this subject based on the ideXlab platform.
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electric field effect on condensed phase molecular systems viii vibrational stark effect and dipolar inversion in a carbon monoxide crystal
Journal of Physical Chemistry C, 2019Co-Authors: Hani Kang, Y W Park, Josee Maurais, Patrick Ayotte, Heon KangAbstract:We applied a strong (≤2.6 × 108 V·m–1) external electric field across a carbon monoxide crystal film at 10 K and studied its effect on the sample with reflection–absorption Infrared Spectroscopy (RAIRS). The vibrational Stark effect (VSE) on the intramolecular CO stretching vibrations of the minor isotopologues (13C16O and 12C18O) reveal the spectral signature of isolated CO vibrations, decoupled from crystal phonons in the solid, as a function of the external electric field magnitude. These so-called molecular CO bands display a VSE with a sensitivity factor of 0.69 ± 0.05 cm–1/(108 V·m–1) in crystalline CO. The VSE on the coupled CO stretching vibrations of the major isotopologue (12C16O) was measured for crystalline and amorphous solid CO films, and the results were analyzed with the help of a classical optics model of RAIRS for thin solid films. In addition to these spectral changes due to VSE, the external electric field facilitates the head-to-tail inversion of CO dipoles in the crystal lattice as a...
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electric field effect on condensed phase molecular systems vii vibrational stark sensitivity of spatially oriented water molecules in an argon matrix
Journal of Physical Chemistry C, 2019Co-Authors: Y W Park, Jong Hyeon Lim, Jin Yong Lee, Heon KangAbstract:The susceptibility of a water molecule to electric fields provides fundamental and essential information for understanding the vibrational spectra of water clusters and condensed-phase water. In this study, the Stark sensitivities for the ν2 bending and ν1 symmetric stretching vibrations of water molecule were experimentally determined. The water molecules isolated in the solid Ar matrix were spatially oriented in the direction of the externally applied field (∼108 V m–1) in the laboratory frame by using the ice-film nanocapacitor method. The signature of the field-induced reorientation of water molecules was observed with reflection–absorption Infrared Spectroscopy. The Stark sensitivities of the D2O vibrations were determined from the field-induced change of vibrational frequencies of the spatially oriented D2O molecules. The Stark sensitivity of the D2O bending vibration was much larger than that of the symmetric stretching vibration, and the two normal modes showed the opposite signs. Isotope dependen...
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electric field effect on condensed phase molecular systems vi field driven orientation of hydrogen chloride in an argon matrix
Journal of Physical Chemistry A, 2018Co-Authors: Hani Kang, Y W Park, Heon KangAbstract:The orientation state of hydrogen chloride (HCl) molecules in a solid argon matrix was reversibly controlled by applying an external electric field of up to 4 × 108 V·m–1 using the ice film capacitor method. The rovibrational transitions of the field-oriented HCl were measured by reflection absorption Infrared Spectroscopy with p-polarized light. Upon application of the external field, free rotation of HCl inside the matrix gradually changed to perturbed rotation and then to a pendular state harmonically bound in the Stark potential well. Further increase in the field strength increased the degree of dipole alignment along the field direction, approaching an asymptotically perfect orientation of the molecules with an average tilt angle of <30° at a field strength above 1 × 108 V·m–1.
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brute force orientation of matrix isolated molecules reversible reorientation of formaldehyde in an argon matrix toward perfect alignment
Angewandte Chemie, 2017Co-Authors: Y W Park, Hani Kang, Heon KangAbstract:Brute force orientation by an electric field is a promising way of controlling the orientation of polar molecules in the gas phase, but its application to condensed-phase molecules has been very limited. We studied the reorientation of formaldehyde molecules in a solid Ar matrix under the influence of a strong electric field using reflection absorption Infrared Spectroscopy. Asymptotically perfect alignment of the formaldehyde molecules along the field was achieved at field strengths exceeding 1×108 V m−1. The vibrational bands of the aligned molecules exhibited a unidirectional Stark shift proportional to the field strength. The reorientation of the molecules was reversible despite the cryogenic solid environment of the system.
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phase transitions of amorphous solid acetone in confined geometry investigated by reflection absorption Infrared Spectroscopy
Journal of Physical Chemistry B, 2014Co-Authors: Sunghwan Shin, Hani Kang, Jun Soo Kim, Heon KangAbstract:We investigated the phase transformations of amorphous solid acetone under confined geometry by preparing acetone films trapped in amorphous solid water (ASW) or CCl4. Reflection absorption Infrared Spectroscopy (RAIRS) and temperature-programmed desorption (TPD) were used to monitor the phase changes of the acetone sample with increasing temperature. An acetone film trapped in ASW shows an abrupt change in the RAIRS features of the acetone vibrational bands during heating from 80 to 100 K, which indicates the transformation of amorphous solid acetone to a molecularly aligned crystalline phase. Further heating of the sample to 140 K produces an isotropic solid phase, and eventually a fluid phase near 157 K, at which the acetone sample is probably trapped in a pressurized, superheated condition inside the ASW matrix. Inside a CCl4 matrix, amorphous solid acetone crystallizes into a different, isotropic structure at ca. 90 K. We propose that the molecularly aligned crystalline phase formed in ASW is created...
Michael Trenary - One of the best experts on this subject based on the ideXlab platform.
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selective hydrogenation of acrolein to propanal on a pseudomorphic pt ru 001 bimetallic surface
Topics in Catalysis, 2018Co-Authors: Dominic A Esan, Michael TrenaryAbstract:The selective hydrogenation of acrolein has been studied on different pseudomorphic Pt/Ru(001) bimetallic surfaces with platinum coverages of 0.28, 1.1, and 3.7 ML, using temperature-programmed reaction Spectroscopy (TPRS), reflection absorption Infrared Spectroscopy (RAIRS), and Auger electron Spectroscopy (AES). The submonolayer (0.28 ML) Pt/Ru(001) surface was found to be inactive towards acrolein hydrogenation and behaves mostly like a clean Ru(001) surface with the platinum layers enhancing the decarbonylation and decomposition pathways. The multilayer (3.7 ML) Pt/Ru(001) surface behaved like a Pt(111) surface with the acrolein mostly decomposing to CO and surface carbon with no observable hydrogenation activity. However, the 1 ML Pt/Ru(001) pseudomorphic surface was found to display properties different from those of Ru(001) and Pt(111) surfaces with the desorption of propanal, the only hydrogenation product, around 330 K, and propylene around 370 K. A submonolayer (0.67 ML) PtRu/Ru(001) alloy system prepared to study the effect of surface mixing (with small amounts of subsurface platinum) gave results similar to those of surface platinum at submonolayer coverages. This suggests that, at submonolayer coverages, there is little difference in the properties of these surfaces with respect to the location of the platinum atoms in the Pt/Ru(001) system.
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surface chemistry of propanal 2 propenol and 1 propanol on ru 001
Physical Chemistry Chemical Physics, 2017Co-Authors: Dominic A Esan, Michael TrenaryAbstract:Adsorption and thermal chemistry of propanal, 2-propenol, and 1-propanol on Ru(001) were studied using temperature programmed reaction Spectroscopy (TPRS) and reflection absorption Infrared Spectroscopy (RAIRS). The results show that each molecule adsorbs molecularly at 90 K and displays the same spectral features as observed for the corresponding liquids after 1.0 L exposures. 2-Propenol was found to molecularly desorb at 200 K, dehydrate to yield propene around 130 K, isomerize to propanal at 180 K, and hydrogenate to 1-propanol at 220 K. Propanal, however, does not undergo isomerization on the surface but desorbs molecularly at 175 and 280 K. Similarly, 1-propanol also desorbs molecularly with two peaks centered at 227, and 298 K. Formaldehyde desorption was observed for each molecule. Furthermore, a reversible hydrogenation-dehydrogenation process was observed between propanal and 1-propanol in the range of 200 to 320 K. These results provided further insights into previous studies on hydrogenation pathways of acrolein on the Ru(001) surface and into the challenges of selectively increasing the yield of the unsaturated alcohol.
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simultaneous monitoring of surface and gas phase species during hydrogenation of acetylene over pt 111 by polarization dependent Infrared Spectroscopy
ACS Catalysis, 2015Co-Authors: Joel D Krooswyk, Iradwikanari Waluyo, Michael TrenaryAbstract:Acetylene hydrogenation was monitored at ambient pressure with polarization-dependent reflection absorption Infrared Spectroscopy (RAIRS), which permitted gas phase and surface species to be simultaneously monitored as C2H2(g) was converted first to C2H4(g) and then to C2H6(g). Experiments in which an acetylene-covered surface was hydrogenated with 1.0 × 10–2 Torr H2 between 120 and 300 K indicated that vinyl is the intermediate species to ethylene formation and that the addition of one H to acetylene is the rate-limiting step of the reaction. At a C2H2(g)/H2(g) ratio of 1:100, the reaction was monitored from 300 to 370 K and separately in a constant pressure and constant temperature reaction at 370 K. Ethylidyne and di-σ-ethylene were observed on the surface in both reactions and were found to be spectator species in the hydrogenation of ethylene to ethane. A minor hydrogenation pathway involves a third species, which is best assigned to an ethylidene intermediate. A small coverage of π-ethylene was also...
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carbon nitrogen bond formation from the reaction of ammonia with dicarbon on the pt 111 surface
Journal of Physical Chemistry C, 2007Co-Authors: Rongping Deng, Michael TrenaryAbstract:The reaction of NH3 with C2 molecules on a Pt(111) surface was investigated using temperature programmed desorption, X-ray photoelectron Spectroscopy (XPS), and reflection absorption Infrared Spectroscopy. Surface C2, which was prepared by dissociative adsorption of acetylene (C2H2) at 750 K, reacts with NH3 to form C−N bonds as revealed by the desorption of HCN and C2N2 at 570 and 650 K, respectively. The formation of C−N bonds was also detected with XPS when the NH3/C2 layer was annealed from 85 to 200 K through the appearance of a chemically shifted C 1s peak at 286.5 eV, which is well-resolved from the unreacted C 1s peak at 284.3 eV. Comparison of calculated and experimental RAIRS data indicates that C−N bond formation involves an HCCNH2 surface intermediate.
Clairemarie Pradier - One of the best experts on this subject based on the ideXlab platform.
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Co-Grafting of Amino–Poly(ethylene glycol) and Magainin I on a TiO2 Surface: Tests of Antifouling and Antibacterial Activities
2016Co-Authors: Jessie Peyre, Vincent Humblot, Jeanmarc Berjeaud, Christophe Méthivier, Clairemarie PradierAbstract:An antimicrobial peptide, Magainin I (Mag), was grafted to a titanium oxide surface, via an antiadhesive poly(ethylene glycol) (PEG) cross-linker. The latter plays a 2-fold part, being antiadhesive, and enabling the covalent immobilization of the peptide. The functionalization was characterized at each step by reflection absorption Infrared Spectroscopy (RAIRS) and X-ray photoelectron Spectroscopy (XPS). The antiadhesive properties of PEG, and antibacterial activity of the anchored Magainin I, were individually tested toward adsorption of bovin serum albumin (BSA) proteins, and against Gram positive bacteria, Listeria ivanovii, respectively. The results reveal that adhesion of both proteins and bacteria have been considerably reduced, accompanied by an inhibition of the growth of remaining adhered bacteria. This work thus offers a novel approach to functionalize oxide surfaces against biofilms and to measure the so-obtained properties in each of the successive steps of a biofilm formation
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optimized grafting of antimicrobial peptides on stainless steel surface and biofilm resistance tests
Colloids and Surfaces B: Biointerfaces, 2011Co-Authors: Arnaud Hequet, Vincent Humblot, Jeanmarc Berjeaud, Clairemarie PradierAbstract:Abstract Antibacterial peptides, magainin I and nisin were covalently bound to stainless steel surfaces. Several procedures of surface functionalisation processes have been investigated and optimized, each step being characterized by polarization modulation reflection absorption Infrared Spectroscopy (PM-RAIRS) and X-ray photoemission Spectroscopy (XPS). Grafting of antibacterial peptides was successfully achieved by a 3 steps functionalisation process on a chitosan polymeric layer. The antibacterial activity of the anchored magainin and nisin was tested against a Gram-positive bacteria, Listeria ivanovii , i.e., the possible survival and attachment of this bacteria, was characterized on modified stainless steel surfaces. The results revealed that the adsorbed peptides reduced the adhesion of bacteria on the functionalised stainless steel surface.
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in depth investigation of protein adsorption on gold surfaces correlating the structure and density to the efficiency of the sensing layer
Journal of Physical Chemistry B, 2008Co-Authors: Souhir Boujday, Aurore Bantegnie, Elisabeth Briand, Pierreguy Marnet, Michele Salmain, Clairemarie PradierAbstract:Protein A (PrA), mouse monoclonal anti-IgG antibody (SAb) and deglycosylated avidin (NAV) were adsorbed on gold surfaces to capture the model rabbit IgG and build three immunosensing platforms. The assembling of immunosensors, their specificity, and the receptor accessibility were monitored by polarization modulation Reflection-Absorption Infrared Spectroscopy (PM-RAIRS) and quartz crystal microbalance with dissipation measurement (QCM-D) at each step. Combining these two techniques allows us to compare both chemical and structural properties of the sensing layers with the former bringing chemical and semiquantitative information on the grafted protein layers, whereas the latter, in addition to the mass uptake, enables us to take the layer rigidity into account. Grafting of the three capture proteins to the transducer surfaces, covered with appropriate self-assembled monolayers, yielded protein layers with variable properties. NAV formed a dense and rigid molecular layer, likely containing protein aggregates, whereas the amount of PrA was below one monolayer resulting in a flexible layer. The amount of immobilized rabbit IgG was different for the three systems with the densest capture protein layer exhibiting the lowest binding capacity. The accessibility of antibodies on the resulting immunosensors measured by interaction with a secondary antirabbit IgG antibody was found to be closely dependent on their coverage as well as on the rigidity of the protein layer. The overall study provides in-depth information on three of the most common immunosensor recognition interfaces and demonstrates the crucial influence of both structure and density of the protein layer on the efficiency of the molecular recognition phenomena.
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adsorption of l lysine on cu 110 a rairs study from uhv to the liquid phase
Langmuir, 2006Co-Authors: Vincent Humblot, Christophe Methivier, Clairemarie PradierAbstract:The adsorption of L-lysine on a Cu(110) surface has been investigated under UHV conditions from the sublimation of a crystalline phase. The adsorption was characterized by Fourier transform reflection absorption Infrared Spectroscopy (FT-RAIRS) during exposure and Auger electron Spectroscopy (AES). At room temperature, the lysine molecules' adsorption geometry varies as a function of the exposure. At low coverage, the molecules are adsorbed via the oxygen atoms of the deprotonated carboxylate group and the nitrogen atom of the amino group. At high coverage, close to the monolayer, the molecules reorient to be anchored to the surface via one oxygen of a sideways-tilted carboxylate moiety. This first step is followed by the growth of multilayers of nonoriented molecules. In contrast, adsorption on an oxygen-modified copper surface leads to a rather disordered layer. The results are compared with the adsorption carried out on a polycrystalline copper surface after immersion in solutions of lysine at various pH values. The adsorption was monitored by polarization modulation Infrared Spectroscopy (PM-IRRAS). The chemistry of the adsorbed molecules is function of the starting chemical form of the lysine molecules imposed by the pH of the solution. The combination of the two techniques and various sets of adsorption conditions will give important insight into the adsorption of biomolecules on metal surfaces and the influence of water and surface oxygen.
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self assembled monolayers of peptide nucleic acids on gold surfaces a spectroscopic study
Langmuir, 2005Co-Authors: Eva Mateomarti, Clairemarie Pradier, Carlos Briones, E Roman, E Briand, Jose A MartingagoAbstract:We have characterized self-assembled monolayers (SAMs) of thiol-derivatized peptide nucleic acid (PNA) chains adsorbed on gold surfaces by using reflection absorption Infrared Spectroscopy (RAIRS) and X-ray photoemission Spectroscopy (XPS) techniques. We have found that the molecular orientation of PNAs strongly depends on surface coverage. At low coverage, PNA chains lie flat on the surface, while at high coverage, PNA molecules realign their molecular axes with the surface normal and form SAMs without the need of co-immobilization of spacers or other adjuvant molecules. The change in the molecular orientation has been studied by Infrared Spectroscopy and it has been confirmed by atomic force microscopy (AFM). PNA immobilization has been followed by analyzing the N(1s) XPS core-level peak. We show that the fine line shape of the N(1s) core-level peak at optimal concentration for biosensing is due to a chemical shift. A combination of the above-mentioned techniques allow us to affirm that the structure of...