scholarly journals Evaluation of the of a numder of natural and modified polysaccharides on the microviscosity of rat erythrocyte membranes using the spin probe method

Surface ◽  
2020 ◽  
Vol 12(27) ◽  
pp. 327-336
Author(s):  
L. V. Ivanov ◽  
◽  
E. V. Shcherbak ◽  
N. T. Kartel ◽  
◽  
...  
Keyword(s):  
Negative Charge ◽  
Dipole Interaction ◽  
Erythrocyte Membranes ◽  
Dialdehyde Starch ◽  
Noticeable Effect ◽  
Imine Group ◽  
Limiting Stage ◽  
Starch Derivatives ◽  
Oppositely Charged ◽  
Positively Charged

Based on the pharmacokinetics of nitazole, proprietary oral administration of the rabbit analyzes various aspects of its use as auxiliary substances in the preparation of dosage forms with controlled absorption of starch, carboxymethyl starch, dialdehyde starch, sodium alginate and chitosan. Our analysis of pharmacokinetic curves revealed a correlation between the presence and magnitude of the negative charge in the polymer of starch derivatives and an increase in the bioavailability of nitazole, the absorption rate estimated by tmax and from the equations describing the curves in the framework of the single-particle absorption model. It can be assumed that the change in the bioavailability of nitazole in the presence of starch derivatives is associated with the ion-ion or ion-dipole interaction of the positively charged imine group of nitazole and negatively charged groups of starch derivatives. Obviously, in the mechanism of absorption of nitazole, the limiting stage is the stage of dissolution of nitazole in the stomach.Since the absorption of nitazole may also depend on the microviscosity of the membranes of the cells of the walls of the stomach, the effect of the above polysaccharides on the microviscosity of the membranes of red blood cells as model cells has been studied. However, the work revealed a noticeable effect of only chitosan on the microviscosity of erythrocyte membranes, in which there was some immobilization of the conformational mobility of the lipid bilayer of the cell membranes upon binding of the oppositely charged chitosan to the surface of the erythrocyte membranes. The remaining negatively charged polysaccharides did not significantly affect the microviscosity of the membranes, apparently due to the processes of electrostatic repulsion from red blood cell cells. The totality of the data obtained has expanded our knowledge about the mechanisms of the possible effect of high molecular weight polysaccharides on the bioavailability of various drugs when creating drugs with controlled absorption.

Effect of Polyphosphate on Removal of Endocrine-Disrupting Chemicals of Nonylphenol and Bisphenol-A by Activated Carbons

2005 ◽  
Vol 40 (4) ◽  
pp. 484-490 ◽  
Author(s):  
Keun J. Choi ◽  
Sang G. Kim ◽  
Chang W. Kim ◽  
Seung H. Kim
Keyword(s):  
Activated Carbon ◽  
Bisphenol A ◽  
Surface Charge ◽  
Activated Carbons ◽  
Endocrine Disrupting Chemicals ◽  
Dipole Interaction ◽  
High Affinity ◽  
Calcium Polyphosphate ◽  
Endocrine Disrupting ◽  
Positively Charged

Abstract This study examined the effect of polyphosphate on removal of endocrine-disrupting chemicals (EDCs) such as nonylphenol and bisphenol-A by activated carbons. It was found that polyphosphate aided in the removal of nonylphenol and bisphenol- A. Polyphosphate reacted with nonylphenol, likely through dipole-dipole interaction, which then improved the nonylphenol removal. Calcium interfered with this reaction by causing competition. It was found that polyphosphate could accumulate on carbon while treating a river. The accumulated polyphosphate then aided nonylphenol removal. The extent of accumulation was dependent on the type of carbon. The accumulation occurred more extensively with the wood-based used carbon than with the coal-based used carbon due to the surface charge of the carbon. The negatively charged wood-based carbon attracted the positively charged calcium-polyphosphate complex more strongly than the uncharged coal-based carbon. The polyphosphate-coated activated carbon was also effective in nonylphenol removal. The effect was different depending on the type of carbon. Polyphosphate readily attached onto the wood-based carbon due to its high affinity for polyphosphate. The attached polyphosphate then improved the nonylphenol removal. However, the coating failed to attach polyphosphate onto the coal-based carbon. The nonylphenol removal performance of the coal-based carbon remained unchanged after the polyphosphate coating.

scholarly journals Solubilization of Charged Porphyrins in Interpolyelectrolyte Complexes: A Computer Study

Polymers ◽  
2021 ◽  
Vol 13 (4) ◽  
pp. 502
Author(s):  
Karel Šindelka ◽  
Zuzana Limpouchová ◽  
Karel Procházka
Keyword(s):  
Dissipative Particle Dynamics ◽  
Water Soluble ◽  
Coarse Grained ◽  
Core Shell ◽  
Computer Study ◽  
Interpolyelectrolyte Complex ◽  
The Core ◽  
Porphyrin Derivatives ◽  
Oppositely Charged ◽  
Positively Charged

Using coarse-grained dissipative particle dynamics (DPD) with explicit electrostatics, we performed (i) an extensive series of simulations of the electrostatic co-assembly of asymmetric oppositely charged copolymers composed of one (either positively or negatively charged) polyelectrolyte (PE) block A and one water-soluble block B and (ii) studied the solubilization of positively charged porphyrin derivatives (P+) in the interpolyelectrolyte complex (IPEC) cores of co-assembled nanoparticles. We studied the stoichiometric mixtures of 137 A10+B25 and 137 A10−B25 chains with moderately hydrophobic A blocks (DPD interaction parameter aAS=35) and hydrophilic B blocks (aBS=25) with 10 to 120 P+ added (aPS=39). The P+ interactions with other components were set to match literature information on their limited solubility and aggregation behavior. The study shows that the moderately soluble P+ molecules easily solubilize in IPEC cores, where they partly replace PE+ and electrostatically crosslink PE− blocks. As the large P+ rings are apt to aggregate, P+ molecules aggregate in IPEC cores. The aggregation, which starts at very low loadings, is promoted by increasing the number of P+ in the mixture. The positively charged copolymers repelled from the central part of IPEC core partially concentrate at the core-shell interface and partially escape into bulk solvent depending on the amount of P+ in the mixture and on their association number, AS. If AS is lower than the ensemble average ⟨AS⟩n, the copolymer chains released from IPEC preferentially concentrate at the core-shell interface, thus increasing AS, which approaches ⟨AS⟩n. If AS>⟨AS⟩n, they escape into the bulk solvent.

First Principles Investigation of the Stability and the Chemical Behavior of Hydrogen in ThCoH4

2011 ◽  
Vol 66 (3) ◽  
pp. 269-274
Author(s):  
Samir F. Matar
Keyword(s):  
Negative Charge ◽  
Geometry Optimization ◽  
Full Geometry Optimization ◽  
Intermetallic Matrix ◽  
Charge Analysis ◽  
The Stability ◽  
The One ◽  
Site Selective ◽  
Bader Charge Analysis ◽  
Positively Charged

We address the changes in the electronic structure brought by the insertion of hydrogen into ThCo leading to the experimentally observed ThCoH4. Full geometry optimization positions the hydrogen in three sites stabilized in the expanded intermetallic matrix. From a Bader charge analysis, hydrogen is found to be in a narrow iono-covalent (~−0.6) to covalent (~−0.3) bonding which should enable site-selective desorption. The overall chemical picture shows a positively charged Thδ+ with the negative charge redistributed over a complex anion {CoH4}δ− with δ~1.8. Nevertheless this charge transfer remains far from the one in the more ionic hydridocobaltate anion CoH54− in Mg2CoH5, due to the largely electropositive character of Mg.

scholarly journals Effect of Hyperglycemia on the Total Surface Charge of the Erythrocyte Membrane in Patients with Metabolic Syndrome

2019 ◽  
Vol 15 (3) ◽  
pp. 322-327
Author(s):  
V. I. Podzolkov ◽  
T. V. Koroleva ◽  
M. G. Kudryavtseva
Keyword(s):  
Metabolic Syndrome ◽  
Surface Charge ◽  
Erythrocyte Membrane ◽  
Negative Charge ◽  
Fasting Blood Glucose ◽  
Microvascular Blood Flow ◽  
Erythrocyte Membranes ◽  
Vascular Changes ◽  
Group 2 ◽  
Group 1

Aim. To study the effect of hyperglycemia on the total surface charge of the erythrocyte membrane (SCEM) in patients with metabolic syndrome (MS).Material and methods. 112 MS patients were examined (45 men and 67 women) (mean age 61.4±7.2 years, average MS duration 8.7±5.2 years). The level of SCEM was determined by adsorption of a positive cationic dye (cationic blue O) on the surface of the plasma membrane of erythrocytes to completely neutralize their negative charge, followed by photometry of the solution and calculation of the number of charges on the cell surface of erythrocytes.Results. In the main group of patients with MS, abdominal obesity was observed in 100% of patients, arterial hypertension – in 73%, hyperglycemia – in 75%, dyslipidemia – in 80%. The level of glycated hemoglobin (HbA1c) was determined in all patients with MS, which was 7.3±1.9%. Patients with MS were conditionally divided according to the level of HbA1c into 2 groups (group 1 – HbA1c from 6.6 to 7.8%, group 2 – more than 7.8%). In MS patients with hyperglycemia, the SCEM values were significantly lower than in the group of patients without hyperglycemia (1.58±0.05×107 and 1.64±0.03×107, respectively; p=0.001)., Significant negative correlations between SCEM and the fasting blood glucose level, hyperglycemia duration, HbA1c level were found in patients with MS.Conclusion. SCEM indices reliably depended on the presence, severity and duration of hyperglycemia, which indicated the effect of impaired carbohydrate metabolism on the state of electric charge of erythrocyte membranes and, therefore, on the mechanisms of microvascular blood flow, thereby contributing to the development of vascular changes in patients with MS.

THE EFFECT OF PROCOAGULANT PHOSPHOLIPID VESICLES WITH NET POSITIVE CHARGE ON THE ACTIVITY OF PROTHROMBINASE

1987 ◽  
Author(s):  
J Rosing ◽  
H Speijer ◽  
J W P Govers-Riemslag ◽  
R F A Zwaal
Keyword(s):  
Vitamin K ◽  
Negative Charge ◽  
Positive Charge ◽  
Coagulation Factor ◽  
Phospholipid Vesicles ◽  
Electrostatic Model ◽  
Acidic Phospholipid ◽  
Positively Charged ◽  
Net Positive Charge ◽  
Prothrombin Activation

It is generally thought that procoagulant phospholipid surfaces that promote the activation of vitamin K-dependent coagulation factors should have a net negative charge in order to promote calcium-dependent binding of the enzymes (FVIIa, FIXa and FXa) and substrates (prothrombin and FX) of the coagulation factor-activating complexes. Two models have been proposed to explain calcium-mediated association of vitamin K-dependent proteins with phospholipid: a) an electrostatic model, in which a positively-charged protein-calcium complex is attracted by a negatively-charged phospholipid surface and b) a chelation model in which a coordination complex is formed between calcium ions, γ-carboxyglutamic acids of the proteins and negatively-charged membrane phospholipids. To study the effect of the electrostatic potential of phospholipid vesicles on their activity in the pro-thrombinase complex the net charge of vesicles was varied by introduction of varying amounts of positively-charged stearylamine in the membrane surface. Introduction of 0-15 mole% stearylamine in phospholipid vesicles that contained 5 mole% phosphatidylseri-ne (PS) hardly affected their activity in prothrombin activation. Electrophoretic analysis showed that vesicles with > 5 mole% stearylamine had a net positive charge. The procoagulant activity of vesicles that contained phosphatidic acid, phosphatidylglyce-rol, phosphatidylinositol or phosphatidyl-glactate (PLac) as acidic phospholipid was much more effected by incorporation of stearylamine. Amounts of stearylamine that compensated the negative charge of acidic phospholipid caused considerable inhibition of the activity of the latter vesicles in prothrombin activation. The comparison of vesicles containing PS and PLac as acidic phospholipid is of special interest. PS and PLac only differ by the presence of NH+ 3-group in the serine moiety of PS. Thus, in spite of the fact that vesicles with PLac are more negatively charged than vesicles with PS, they are less procoagulant. Our results show that a) although procoagulant membranes have to contain acidic phospholipids there is no requirement for a net negative charge, b) the amino group of phosphatidylserine has an important function in the interaction of procoagulant membranes with vitamin K-dependent proteins and c) the chelation model can satisfactorily explain calcium-mediated lipid-protein association.

scholarly journals The Position of Solid Carbon Dioxide in the Triboelectric Series

2019 ◽  
Vol 72 (8) ◽  
pp. 633 ◽  
Author(s):  
Jinyang Zhang ◽  
Simone Ciampi
Keyword(s):  
Carbon Dioxide ◽  
Negative Charge ◽  
Plastic Material ◽  
Indirect Evidence ◽  
Liquid Carbon ◽  
Solid Carbon Dioxide ◽  
Dry Ice ◽  
First Time ◽  
Charge Sign ◽  
Positively Charged

The process of releasing liquid carbon dioxide from a fire extinguisher is accompanied by a strong static charging of the plastic material making up the extinguisher discharge horn. Firefighters often report an electric shock when operating CO2 extinguishers, but the origin of this electrostatic hazard is largely unknown. Here, we begin to investigate this phenomenon, and test the hypothesis of plastic samples being tribocharged on contact with rapidly flowing solid CO2. Using Faraday pail measurements, we show that non-conductive polymers gain a net static charge when brought in and out of contact with dry ice (solid CO2). These measurements of charge sign and magnitude give indirect evidence helping to place solid CO2 for the first time on the triboelectric series. Polydimethylsiloxane (PDMS), polytetrafluoroethylene (PTFE), and polyvinyl chloride (PVC) samples acquire a negative charge when rubbed against dry ice, whereas poly(methyl methacrylate) (PMMA), glass, and nylon surfaces become positively charged. Therefore, we suggest the position of dry ice in the triboelectric series to be close to that of materials with stable cations and unstable anions, possibly locating it between PMMA and PVC.

scholarly journals Analysis of Pole-Ascending–Descending Action by Insects Subjected to High Voltage Electric Fields

Insects ◽  
2020 ◽  
Vol 11 (3) ◽  
pp. 187 ◽  
Author(s):  
Yoshinori Matsuda ◽  
Yoshihiro Takikawa ◽  
Koji Kakutani ◽  
Teruo Nonomura ◽  
Hideyoshi Toyoda
Keyword(s):  
Electric Field ◽  
Electric Fields ◽  
Negative Charge ◽  
Sitophilus Oryzae ◽  
Experimental System ◽  
Insect Behavior ◽  
Free Electrons ◽  
Current Voltage ◽  
Direct Current Voltage ◽  
Oppositely Charged

The present study was conducted to establish an electrostatic-based experimental system to enable new investigations of insect behavior. The instrument consists of an insulated conducting copper ring (ICR) linked to a direct current voltage generator to supply a negative charge to an ICR and a grounded aluminum pole (AP) passed vertically through the center of the horizontal ICR. An electric field was formed between the ICR and the AP. Rice weevil (Sitophilus oryzae) was selected as a model insect due to its habit of climbing erect poles. The electric field produced a force that could be imposed on the insect. In fact, the negative electricity (free electrons) was forced out of the insect to polarize its body positively. Eventually, the insect was attracted to the oppositely charged ICR. The force became weaker on the lower regions of the pole; the insects sensed the weaker force with their antennae, quickly stopped climbing, and retraced their steps. These behaviors led to a pole-ascending–descending action by the insect, which was highly reproducible and precisely corresponded to the changed expansion of the electric field. Other pole-climbing insects including the cigarette beetle (Lasioderma serricorne), which was shown to adopt the same behavior.

scholarly journals Compositional and Temperature Effects on the Rheological Properties of Polyelectrolyte–Surfactant Hydrogels

Polymers ◽  
2019 ◽  
Vol 11 (5) ◽  
pp. 927 ◽  
Author(s):  
Jiří Smilek ◽  
Sabína Jarábková ◽  
Tomáš Velcer ◽  
Miloslav Pekař
Keyword(s):  
Ionic Strength ◽  
Rheological Properties ◽  
Surfactant Concentration ◽  
Background Electrolyte ◽  
Effect Of Temperature ◽  
Physical Interactions ◽  
Chain Conformations ◽  
Oppositely Charged ◽  
Electrolyte Ph ◽  
Positively Charged

The rheological properties of hydrogels prepared by physical interactions between oppositely charged polyelectrolyte and surfactant in micellar form were studied. Specifically, hyaluronan was employed as a negatively charged polyelectrolyte and Septonex (carbethopendecinium bromide) as a cationic surfactant. Amino-modified dextran was used as a positively charged polyelectrolyte interacting with sodium dodecylsulphate as an anionic surfactant. The effects of the preparation method, surfactant concentration, ionic strength (the concentration of NaCl background electrolyte), pH (buffers), multivalent cations, and elevated temperature on the properties were investigated. The formation of gels required an optimum ionic strength (set by the NaCl solution), ranging from 0.15–0.3 M regardless of the type of hydrogel system and surfactant concentration. The other compositional effects and the effect of temperature were dependent on the polyelectrolyte type or its molecular weight. General differences between the behaviour of hyaluronan-based and cationized dextran-based materials were attributed to differences in the chain conformations of the two biopolymers and in the accessibility of their charged groups.

scholarly journals An extension of Maxwell's electro-magnetic theory of light to include dispersion, metallic reflection, and allied phenomena

1898 ◽  
Vol 63 (389-400) ◽  
pp. 91-92
Keyword(s):  
Homogeneous Medium ◽  
Potential Difference ◽  
Electric Moment ◽  
Magnetic Theory ◽  
Electro Magnetic ◽  
Oppositely Charged ◽  
Positively Charged

A dielectric, like an electrolyte, is assumed to consist of molecules, each comprising, in the simplest case, two oppositely charged atoms at a definite distance apart. In a homogeneous medium, when not subjected to electric strain, these molecules will be arranged in such a manner that any element of volume will possess no resultant electric moment. If a definite potential difference be maintained between any two parallel planes in the medium, the positively charged atoms will move to points of lower, and the negatively charged atoms to points of higher, potential.

scholarly journals Structural requirements for the utilization of ascorbate analogues in the prolyl 4-hydroxylase reaction

1994 ◽  
Vol 300 (1) ◽  
pp. 75-79 ◽  
Author(s):  
G Tschank ◽  
J Sanders ◽  
K H Baringhaus ◽  
F Dallacker ◽  
K I Kivirikko ◽  
...  
Keyword(s):  
Negative Charge ◽  
Substrate Inhibition ◽  
Side Chain ◽  
Structural Requirements ◽  
Response Behaviour ◽  
Structural Analogues ◽  
Microsomal Hydroxylation ◽  
Ring Position ◽  
Charged Group ◽  
Positively Charged

The ability of structural analogues of ascorbate to serve as substitutes for this reducing agent in the prolyl 4-hydroxylase reaction was studied. In experiments using the purified enzyme, variations of the compounds′ side chain were compatible with co-substrate activity. The presence of very large hydrophobic substituents or a positively charged group caused an increase in the observed Km values. A negative charge and smaller modifications did not change the affinity to the enzyme when compared with L-ascorbate. 6-Bromo-6-deoxy-L-ascorbate had a lower Km than the physiological reductant. Substitution at the -OH group in ring position 3 prevented binding to the enzyme. The same pattern of activity was observed when the full and uncoupled prolyl 4-hydroxylase reactions were studied. The Vmax. values with all compounds were similar. The reaction of microsomal prolyl 4-hydroxylase was supported by D-isoascorbate, O6-tosyl-L-ascorbate and 5-deoxy-L-ascorbate, giving the same dose-response behaviour as L-ascorbate itself. Again, 6-bromo-6-deoxy-L-ascorbate gave a lower Km and a similar Vmax. value. L-Ascorbic acid 6-carboxylate produced substrate inhibition at concentrations above 0.3 mM. The Km and Vmax. values calculated from concentrations up to 0.2 mM were similar to those of L-ascorbate. The enzyme activity observed with 6-amino-6-deoxy-L-ascorbate was very low in the microsomal hydroxylation system. The calculated Vmax. value was lower than that of L-ascorbate, suggesting a restriction of the access of this compound to the enzyme.

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