scholarly journals Composite systems for medical purposes, created on the basis of hydrophobic silica

Surface ◽  
2021 ◽  
Vol 13(28) ◽  
pp. 246-275
Author(s):  
V. V. Turov ◽  
◽  
P. P. Gorbyk ◽  
T. V. Krupska ◽  
S. P. Turanska ◽  
...  
Keyword(s):  
Bound Water ◽  
Adsorbed Water ◽  
Strong Acid ◽  
Acid Media ◽  
Water Binding ◽  
Composite Systems ◽  
Hydrophobic Materials ◽  
Protein Molecules ◽  
Hydrophobic Component ◽  
Different Order

Composite systems with certain cytotoxic (AM1/lectin) and adsorption (AM1/gelatin) activity have been developed on the basis of methyl silica and protein molecules – lectin and gelatin. For both types of composites, mechanisms of water binding to the surface and methods of transferring of hydrophobic materials into the aquatic environment have been investigated. The state of interfacial water in air, organic and acid media was studied. It has been found that the presence of a hydrophobic component in composites stabilizes of surface water in a weakly associated state, when a significant part of water molecules does not form hydrogen bonds. Liquid hydrophobic medium enhances this effect, and the strong acid (trifluoroacetic), added to it, promotes the transition of water to a strongly associated state. It has been shown that the redistribution of water in the interparticle intervals of AM1 with protein molecules immobilized on their surface changes under the influence of mechanical loads. Mechanoactivated samples are characterized by the possibility of water penetration into the spaces between the primary particles of methyl silica. It has been shown that immobilization of lectin on the surface of AM1 is accompanied by an increase in the interfacial energy gS from 4.1 to 5.2 J/g. This is due to an increase in the concentration of strongly bound water. If we analyze the changes in the distributions of radii R of the clusters of adsorbed water, we can state that in the water adsorbed by native lectin molecules, there are two main maxima at R = 1 and 3 nm. In the immobilized state, the maximum at R = 1 nm is present in both types of water (of different order), but the second maximum is observed only for more ordered associates.

scholarly journals Use of microcoagulation effect to control water binding in a heterogeneous polymethylsiloxane/silica/water system

2020 ◽  
Vol 21 (1) ◽  
pp. 132-139
Author(s):  
V. V. Turov ◽  
I. I. Gerashchenko ◽  
T. V. Krupskaya ◽  
N. Yu. Klymenko ◽  
K. O. Stepanuk
Keyword(s):  
Interfacial Energy ◽  
Mechanical Load ◽  
Heterogeneous Systems ◽  
Water System ◽  
Bound Water ◽  
Water Binding ◽  
Mechanical Loads ◽  
Composite Systems ◽  
System A ◽  
Surface Active

The binding of water in heterogeneous systems containing polymethylsiloxane (PMS) pyrogenic nanosilica (A-300) water and the surface-active substance decametoxin (DMT) was studied. Composite systems were created using metered mechanical loads. The low-temperature 1H NMR spectroscopy was used to measure the structural and thermodynamic parameters of bound water. It is shown that when filling PMS interparticle gaps with hydrocompaction, the interfacial energy of water in the interparticle gaps of hydrophobic PMS with the same hydration is twice as large as the interfacial energy of water in hydrophilic silica A-300. This is due to the smaller linear dimensions of the interparticle gaps in the ICP compared with the A-300. In the composite system, A-300/PMS/DMT/H2O, a non-additive growth of water binding energy is observed, which is likely due to the formation, under the influence of mechanical load in the presence of water, of microheterogeneous sites, consisting mainly of the hydrophobic and hydrophilic components (microcoagulation). Thus, using mechanical loads, you can control the adsorption properties of composite systems.

Proton magnetic relaxation of water sorbed by methaemoglobin crystals

1973 ◽  
Vol 331 (1587) ◽  
pp. 457-468 ◽  
Keyword(s):  
Relaxation Rate ◽  
Relaxation Times ◽  
Transverse Relaxation Rate ◽  
Ferric Ions ◽  
Transverse Relaxation ◽  
Water Binding ◽  
Adsorption Sites ◽  
Protein Molecules ◽  
Proton Magnetic Relaxation ◽  
Limiting Value

P. m. r. relaxation times ( T 1 and T 2 ) have been measured as a function of regain and temperature for water sorbed by lyophilized methaemoglobin. The purpose of the work was to gain information regarding the nature and extent of water binding by the protein molecules. The T 1 results are interpreted in terms of an exchange between the sixth ligand position of the Fe (III) and other adsorption sites on the protein. At high temperatures the relaxation rate at a given regain reaches a limiting value which allows the fraction of ferric ions hydrated to be calculated. Above 16% regain all the Fe (III) is hydrated. At 21 and 35% regains a maximum appears in the relaxation rate at about -46 °C indicating a contribution from a more mobile phase which produces a T 1 minimum at that temperature. The T 2 data are consistent with a model in which the main contribution to the transverse relaxation rate comes from a tightly bound fraction of the water with ω 0 Ƭ c ≫1. The temperature dependence of T 2 exhibits three different regions: ( a ) a low temperature region where lg T 2 ∝ T -1 ; ( b ) an intermediate region with a steeper increase of T 2 with temperature; and ( c ) a high temperature where T 2 levels off.

Rearrangement of 1-acylaziridines to oxazolinium cations in strong acid media

1970 ◽  
Vol 35 (4) ◽  
pp. 1187-1190 ◽  
Author(s):  
Charles U. Pittman ◽  
Samuel P. McManus
Keyword(s):  
Strong Acid ◽  
Acid Media

Kinetics and mechanism of the formation of methacrylamide from 2-methyl-2-sulphatopropionamide in strong acid media

1991 ◽  
pp. 417 ◽  
Author(s):  
C. Dennis Hall ◽  
Christopher J. Leeding ◽  
Stephen Jones ◽  
Stephen Case-Green ◽  
Ian Sanderson ◽  
...  
Keyword(s):  
Strong Acid ◽  
Kinetics And Mechanism ◽  
Acid Media

Pressure effect on hydrogen isotope exchange kinetics in chymotrypsinogen investigated by FT-IR spectroscopy

1991 ◽  
Vol 69 (11) ◽  
pp. 1699-1704 ◽  
Author(s):  
P. T. T. Wong
Keyword(s):  
High Pressure ◽  
Exchange Rate ◽  
Rate Constant ◽  
Bound Water ◽  
Pressure Effects ◽  
Protein Molecules ◽  
Fast Exchange ◽  
Exchange Rate Constant ◽  
Hydrogen Deuterium ◽  
Exchange Kinetics

Hydrogen/deuterium (H/D) exchange rate constants in chymotrypsinogen have been determined at several pressures up to 28.9 kbar by FTIR spectroscopy. The secondary structure of the protein molecules was monitored simultaneously at the corresponding pressures by the intensity redistribution of the infrared amide I band at these pressures. As in other proteins, the labile protons on the amide groups in chymotrypsinogen can, to a good approximation, be separated into two classes, each with distinct first order H/D exchange rates constants in the time period from 10 min to ~24 h. The fast exchange rate constant increases while the slow exchange rate constant decreases with increasing pressure. The increase in the fast exchange rate constant at high pressure is largely associated with the pressure-induced unfolding of the protein molecules. At extremely high pressure (12.8 kbar), in addition to the unfolding of protein molecules, pressure induced a distortion and weakening of the hydrogen bonds of the fold protein segments also contribute to an increase in the overall H/D exchange rate. The present results confirm that when chymotrypsinogen is dissolved in D2O, a considerable amount of D2O molecules is bound to the protein molecules on the surface as well as in the interior cavities of the molecules. The H/D exchange takes place between these bound D2O and the protons in the protein molecules. The mechanism of the H/D exchange and the interior dynamics in proteins are discussed on the basis of the present results. Key words: hydrogen/deuterium exchange, exchange kinetics, rate constant, pressure effects, infrared spectroscopy, protein, conformation structure, bound water.

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