scholarly journals Interaction of N-acetylneyraminic acid with surface of silica with fructose in aqueous solution

2021 ◽  
Vol 22 (1) ◽  
pp. 94-100
Author(s):  
L.M. Ushakova ◽  
E.M. Demianenko ◽  
M.I. Terets ◽  
V.V. Lobanov ◽  
N.T. Kartel
Keyword(s):  
Density Functional ◽  
Silica Surface ◽  
Experimental Fact ◽  
Adsorption Complex ◽  
Hydrated Silica ◽  
Energy Effect ◽  
Functional Theory ◽  
Acetylneuraminic Acid ◽  
Adsorption Complexes ◽  
Chemical Simulation

Quantum chemical simulation of the adsorption of N acetylneuraminic acid (NANA) on the surface of silica with the participation of the fructose molecule by the method of density functional theory B3LYP, 6-31G (d, p) was done. The influence of the solvent was taken into account in the supermolecular and continuum approximations, and a cluster approach was used for the adsorption complexes. NANA adsorption of the hydrated silica surface was considered as a process of replacement of water molecules on the silica surface by adsorbate molecules. Two schemes of influence of fructose molecule on NANA adsorption are considered. According to the first scheme, the hydrated NANA molecule interacts with the hydrated silicon-fructose adsorption complex. According to the second scheme, the cluster of hydrated silica interacts with the hydrated NANA-fructose complex. The energy of intermolecular interaction according to the scheme 1 is -9.2 kJ / mol, which is significantly lower compared to the same value with the participation of glucose or sucrose (-20.5 and -86.2 kJ / mol). Scheme 2 proved to be a thermodynamically unfavorable process, as its energy effect is +6.9 kJ / mol, in contrast to similar processes for glucose (-21.8) and sucrose (-87.7 kJ / mol). This confirms the experimental fact of the interaction of substances in a mixture of NANA with carbohydrates in relation to the interaction with silica in comparison with the interaction of substances with silica separately.

Adsorption of catechol on a wet silica surface: density functional theory study

2011 ◽  
Vol 130 (2-3) ◽  
pp. 333-339 ◽  
Author(s):  
Shabeer Ahmad Mian ◽  
Xingfa Gao ◽  
Shigeru Nagase ◽  
Joonkyung Jang
Keyword(s):  
Density Functional Theory ◽  
Surface Density ◽  
Density Functional ◽  
Silica Surface ◽  
Density Functional Theory Study ◽  
Functional Theory

A density functional theory study on the underwater adhesion of catechol onto a graphite surface

2021 ◽  
Author(s):  
Ramesh Kumar Chitumalla ◽  
Kiduk Kim ◽  
Xingfa Gao ◽  
Joonkyung Jang
Keyword(s):  
Density Functional Theory ◽  
Density Functional ◽  
Silica Surface ◽  
Graphite Surface ◽  
Density Functional Theory Study ◽  
Functional Theory ◽  
Wet Adhesion ◽  
Underwater Adhesion ◽  
Dft Simulations ◽  
Periodic Dft

By employing periodic-DFT simulations, we unveil that the wet adhesion of mussels onto a hydrophobic graphite surface is significantly strong and is comparable with that on a hydrophilic silica surface.

Acidity constant and DFT-based modelling of pH-responsive alendronate loading and releasing on propylamine modified silica surface

2020 ◽  
Author(s):  
Khalid Ahmed ◽  
Shaukatali Inamdar ◽  
Nashiour Rohman ◽  
Adam Skelton
Keyword(s):  
Density Functional ◽  
Silica Surface ◽  
Mesoporous Silica Nanoparticles ◽  
Drug Loading ◽  
Acidity Constant ◽  
Ph Responsive ◽  
Modified Silica ◽  
Functional Theory ◽  
Ph Dependent ◽  
Computational Methodology

A computational methodology that couples the acidity (Ka) and density functional theory (DFT) calculations has been developed to explain the pH-dependent drug loading and releasing by mesoporous silica nanoparticles. The...

scholarly journals 5-fluorouracil adsorption on hydrated silica: density functional theory based-study

Adsorption ◽  
2017 ◽  
Vol 23 (2-3) ◽  
pp. 321-325 ◽  
Author(s):  
A. Díaz Compañy ◽  
A. Juan ◽  
G. Brizuela ◽  
S. Simonetti
Keyword(s):  
Density Functional Theory ◽  
Density Functional ◽  
Hydrated Silica ◽  
Functional Theory

scholarly journals A combined NMR, MD and DFT conformational analysis of 9-O-acetyl sialic acid-containing GM3 ganglioside glycan and its 9-N-acetyl mimic

Glycobiology ◽  
2020 ◽  
Vol 30 (10) ◽  
pp. 787-801 ◽  
Author(s):  
Wanqing Li ◽  
Marcos D Battistel ◽  
Hannah Reeves ◽  
Lisa Oh ◽  
Hai Yu ◽  
...  
Keyword(s):  
Conformational Changes ◽  
Density Functional ◽  
Chemical Shifts ◽  
Coupling Constants ◽  
Functional Theory ◽  
Acetylneuraminic Acid ◽  
Nuclear Overhauser ◽  
Nuclear Overhauser Effects ◽  
Intramolecular Hydrogen

Abstract O-Acetylation of carbohydrates such as sialic acids is common in nature, but its role is not clearly understood due to the lability of O-acetyl groups. We demonstrated previously that 9-acetamido-9-deoxy-N-acetylneuraminic acid (Neu5Ac9NAc) is a chemically and biologically stable mimic of the 9-O-acetyl-N-acetylneuraminic acid (Neu5,9Ac2) of the corresponding sialoglycans. Here, a systematic nuclear magnetic resonance (NMR) spectroscopic and molecular dynamics (MD) simulation study was undertaken for Neu5,9Ac2-containing GM3 ganglioside glycan (GM3-glycan) and its Neu5Ac9NAc analog. GM3-glycan with Neu5Ac as the non-O-acetyl form of Neu5,9Ac2 was used as a control. Complete 1H and 13C NMR chemical shift assignments, three-bond 1H-13C trans-glycosidic coupling constants (3JCH), accurate 1H-1H coupling constants (3JHH), nuclear Overhauser effects and hydrogen bonding detection were carried out. Results show that structural modification (O- or N-acetylation) on the C-9 of Neu5Ac in GM3 glycan does not cause significant conformational changes on either its glycosidic dihedral angles or its secondary structure. All structural differences are confined to the Neu5Ac glycerol chain, and minor temperature-dependent changes are seen in the aglycone portion. We also used Density Functional Theory (DFT) quantum mechanical calculations to improve currently used 3JHH Karplus relations. Furthermore, OH chemical shifts were assigned at −10°C and no evidence of an intramolecular hydrogen bond was observed. The results provide additional evidence regarding structural similarities between sialosides containing 9-N-acetylated and 9-O-acetylated Neu5Ac and support the opportunity of using 9-N-acetylated Neu5Ac as a stable mimic to study the biochemical role of 9-O-acetylated Neu5Ac.

Adsorption behavior of O2 on vacancy-defected graphene with transition-metal dopants: A theoretical study

2018 ◽  
Vol 32 (27) ◽  
pp. 1850304 ◽  
Author(s):  
Qingxiao Zhou ◽  
Yongliang Yong ◽  
Xiangying Su ◽  
Weiwei Ju ◽  
Zhibing Fu ◽  
...  
Keyword(s):  
Transition Metal ◽  
Density Functional ◽  
Theoretical Study ◽  
Dft Method ◽  
Vacancy Defect ◽  
Functional Theory ◽  
Defect Sites ◽  
The Density Functional Theory ◽  
Adsorption Complexes ◽  
Mn Doped

The influence of vacancy and dopants on the adsorption of O2 molecule on graphene was explored by using the density functional theory (DFT) method. The results indicated that the presence of vacancy-defect improved the sensitivity of graphene toward the O2 molecule. Furthermore, the two O atoms of O2 molecule separately formed chemical bonds with C atoms at the defect sites. After introducing the transition-metal (TM) dopants, the O–O bond length of O2 molecule was enlarged by the adsorption on the surface of graphene. Furthermore, the Mn-doped adsorption complexes became magnetic, which was mainly contributed by the O-2p and Mn-3d orbitals.

DFT calculations of tin dioxide crystals containing heavily-doped fluorine

2014 ◽  
Vol 13 (08) ◽  
pp. 1450069 ◽  
Author(s):  
Freddy Marcillo ◽  
Arvids Stashans
Keyword(s):  
First Principles ◽  
Density Functional ◽  
Tin Dioxide ◽  
Empirical Studies ◽  
Experimental Fact ◽  
First Principles Calculations ◽  
Generalized Gradient ◽  
Functional Theory ◽  
The Density Functional Theory ◽  
Heavily Doped

First-principles calculations based on the density functional theory (DFT) within the generalized gradient approximation have been used in the present research. Fluorine doping in the SnO 2 crystals has been carried out considering a number of different defect concentrations. Dopant influence upon structural, electronic and electrical properties of the tin dioxide has been discussed in detail. The system presents n-type electrical conductivity relating our work directly to a number of empirical studies in this area. An experimental fact that n-type conductivity tends to decrease at rather high fluorine impurity rates has been explained at the theoretical level.

scholarly journals First-Principles Density Functional Theory Characterisation of the Adsorption Complexes of H3AsO3 on Cobalt Ferrite (Fe2CoO4) Surfaces

Minerals ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 195
Author(s):  
Eloise C. Lewis ◽  
Nelson Y. Dzade
Keyword(s):  
Density Functional Theory ◽  
Density Functional ◽  
Cobalt Ferrite ◽  
Outer Sphere ◽  
Arsenic Species ◽  
Functional Theory ◽  
Adsorption Complexes ◽  
Aqueous Conditions ◽  
Explicit Solvation ◽  
Outer Sphere Complexes

The mobility of arsenic in aqueous systems can be controlled by its adsorption onto the surfaces of iron oxide minerals such as cobalt ferrite (Fe2CoO4). In this work, the adsorption energies, geometries, and vibrational properties of the most common form of As(III), arsenous acid (H3AsO3), onto the low-index (001), (110), and (111) surfaces of Fe2CoO4 have been investigated under dry and aqueous conditions using periodic density functional theory (DFT) calculations. The dry and hydroxylated surfaces of Fe2CoO4 steadily followed an order of increasing surface energy, and thus decreasing stability, of (001) < (111) < (110). Consequently, the favourability of H3AsO3 adsorption increased in the same order, favouring the least stable (110) surface. However, by analysis of the equilibrium crystal morphologies, this surface is unlikely to occur naturally. The surfaces were demonstrated to be further stabilised by the introduction of H2O/OH species, which coordinate the surface cations, providing a closer match to the bulk coordination of the surface species. The adsorption complexes of H3AsO3 on the hydroxylated Fe2CoO4 surfaces with the inclusion of explicit solvation molecules are found to be generally more stable than on the dry surfaces, demonstrating the importance of hydrogen-bonded interactions. Inner-sphere complexes involving bonds between the surface cations and molecular O atoms were strongly favoured over outer-sphere complexes. On the dry surfaces, deprotonated bidentate binuclear configurations were most thermodynamically favoured, whereas monodentate mononuclear configurations were typically more prevalent on the hydroxylated surfaces. Vibrational frequencies were analysed to ascertain the stabilities of the different adsorption complexes and to assign the As-O and O-H stretching modes of the adsorbed arsenic species. Our results highlight the importance of cobalt as a potential adsorbent for arsenic contaminated water treatment.

scholarly journals A quantum chemistry study on the interaction between silica surface and aqueous alkaline solutions

2018 ◽  
Vol 19 (1) ◽  
pp. 74-78
Author(s):  
A. A. Kravchenko ◽  
E. M. Demianenko ◽  
A. G. Grebenyuk ◽  
V. V. Lobanov
Keyword(s):  
Density Functional ◽  
Silica Surface ◽  
Density Functional Theory Method ◽  
Equilibrium Structure ◽  
Basis Set ◽  
Alkaline Solutions ◽  
Quantum Chemical Analysis ◽  
Functional Theory ◽  
Exchange Correlation ◽  
Extended Basis

A quantum chemical analysis has been carried out of the equilibrium structure and energy parameters of hydrated Li+, Na+, and K+ cations interacting with ionized silica surface by means of density functional theory method with extended basis set 6-31++G(d,p) and exchange-correlation functional B3LYP. The calculated adsorption energy values related to those cations reproduce the experimental adsorption row of alkali metal cations at pH = 10.

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