Chitosan Coated Alginate Microparticles for Oral Vaccine Delivery

2012 ◽  
Vol 506 ◽  
pp. 469-472
Author(s):  
Tittaya Suksamran ◽  
Theerasak Rojanarata ◽  
Tanasait Ngawhirunpat ◽  
Suwannee Panomsuk ◽  
Praneet Opanasopit
Keyword(s):  
Release Rate ◽  
Negative Charge ◽  
Positive Charge ◽  
Oral Vaccine ◽  
Entrapment Efficiency ◽  
Cross Linking ◽  
Antigen Delivery ◽  
Particle Sizes ◽  
Considerable Potential ◽  
Electrohydrodynamic Spraying

The aim of this study was to prepare Caalginate and chitosan (CS)Caalginate microparticles for peroral delivery of ovalbumin (OVA). Microparticles containing different loading of OVA (10, 20 and 40 % w/w) were prepared by cross-linking alginate with calcium chloride using an electrohydrodynamic spraying technique, and then coated with CS. The particle sizes of OVA-loaded microparticles were in the range of 1-5 µm. The negative charge was obtained for Caalginate microparticles (-14±1.9 mV) whereas CSCaalginate microparticles were positive charge (+6.06±3.4 mV). Caalginate microparticles with initial 20% w/w OVA showed the highest entrapment efficiency and amount of OVA content (24.91±0.4% and 33.22±0.1 mg/g, respectively) as similar to CSCaalginate microparticles with initial 20% w/w OVA that showed the highest entrapment efficiency and amount of OVA content (35.74±0.1% and 10.35±0.5 mg/g, respectively). It was found that the release rate of OVA from Caalginate microparticles was higher than CSCaalginate microparticles, and the lowest release rate, sustained release for 24 h, was found in the initial 40% w/w OVA. This study revealed that CSCaalginate microparticles have a considerable potential as controlled release antigen delivery systems.

Development of Chitosan Nanoparticles for Gene Delivery Using Electrohydrodynamic Spraying Techniques

2011 ◽  
Vol 194-196 ◽  
pp. 541-544
Author(s):  
Orapan Paecharoenchai ◽  
Tittaya Suksamran ◽  
Tanasait Ngawhirunpat ◽  
Theerasak Rojanarata ◽  
Praneet Opanasopit
Keyword(s):  
Release Rate ◽  
Chitosan Nanoparticles ◽  
Electrical Potential ◽  
Spherical Shape ◽  
Entrapment Efficiency ◽  
Dna Amount ◽  
Dna Release ◽  
Particle Size And Shape ◽  
Electrohydrodynamic Spraying

Chitosan nanoparticles were prepared by crosslinking chitosan (CS) with tripolyphosphate (TPP) solution using electrohydrodynamic spraying technique. The effects of CS and TPP concentration as well as electrical potential on particle size and shape were investigated. Appropriated formulations for preparing nanoparticles were chosen to encapsulate DNA. In vitro evaluation of the obtained nanoparticles as gene carrier such as entrapment efficiency and DNA release was performed. The results showed that 2 mg/ml TPP was dropped at 10 kV into 1 mg/ml CS (MW 20 kDa (F1) and 200 kDa (F2)) yielded the spherical shape and small particles of 227.67 and 240.33 nm, respectively. In DNA entrapment study, all formulations were tested by altering DNA loading to 10, 25 and 50 mg/g of CS. The results revealed that F1 with initial DNA 10 mg/g of CS showed the highest entrapment efficiency of 95.31%. While F2 with initial DNA of 25 mg/g of CS showed the highest entrapment efficiency of 89.16%. The DNA release study from CS nanoparticles indicated that the increasing of DNA amount slowed down the release rate. F1 and F2 with the initial DNA of 10 mg/g of CS had faster release rate than those with 25 and 50 mg/g of CS. It can be concluded that F1 yielded the nanoparticles with the smallest size, high DNA entrapment efficiency and enabled DNA sustained release.

scholarly journals Zerumbone Inhibits Helicobacter pylori Urease Activity

Molecules ◽  
2021 ◽  
Vol 26 (9) ◽  
pp. 2663
Author(s):  
Hyun Jun Woo ◽  
Ji Yeong Yang ◽  
Pyeongjae Lee ◽  
Jong-Bae Kim ◽  
Sa-Hyun Kim
Keyword(s):  
Helicobacter Pylori ◽  
Carbon Atom ◽  
Natural Compound ◽  
Urease Activity ◽  
Negative Charge ◽  
Positive Charge ◽  
Gastric Epithelium ◽  
Functional Inhibition ◽  
Electrical Gradient ◽  
H Pylori

Helicobacter pylori (H. pylori) produces urease in order to improve its settlement and growth in the human gastric epithelium. Urease inhibitors likely represent potentially powerful therapeutics for treating H. pylori; however, their instability and toxicity have proven problematic in human clinical trials. In this study, we investigate the ability of a natural compound extracted from Zingiber zerumbet Smith, zerumbone, to inhibit the urease activity of H. pylori by formation of urease dimers, trimers, or tetramers. As an oxygen atom possesses stronger electronegativity than the first carbon atom bonded to it, in the zerumbone structure, the neighboring second carbon atom shows a relatively negative charge (δ−) and the next carbon atom shows a positive charge (δ+), sequentially. Due to this electrical gradient, it is possible that H. pylori urease with its negative charges (such as thiol radicals) might bind to the β-position carbon of zerumbone. Our results show that zerumbone dimerized, trimerized, or tetramerized with both H. pylori urease A and urease B molecules, and that this formation of complex inhibited H. pylori urease activity. Although zerumbone did not affect either gene transcription or the protein expression of urease A and urease B, our study demonstrated that zerumbone could effectively dimerize with both urease molecules and caused significant functional inhibition of urease activity. In short, our findings suggest that zerumbone may be an effective H. pylori urease inhibitor that may be suitable for therapeutic use in humans.

scholarly journals FORMULATION AND EVALUATION OF PERINDOPRIL MICROENCAPSULES BY USING DIFFERENT POLYMER

2017 ◽  
Vol 10 (2) ◽  
pp. 153
Author(s):  
Leena Jacob ◽  
Abhilash Tv ◽  
Shajan Abraham
Keyword(s):  
Drug Delivery ◽  
Particle Size ◽  
Release Rate ◽  
Oral Drug Delivery ◽  
Entrapment Efficiency ◽  
Water Soluble ◽  
Oral Drug ◽  
Percentage Yield ◽  
Drug Entrapment Efficiency

Objective: The study was carried out with an objective to achieve a potential sustained release oral drug delivery system of an antihypertensive drug, Perindopril which is a ACE inhibitor having half life of 2 hours. Perindopril is water soluble drug, so we can control or delay the release rate of drug by using release retarding polymers. This may also decrease the toxic side effects by preventing the high initial concentration in the blood.Method: Microcapsules were prepared by solvent evaporation technique using Eudragit L100 and Ethyl cellulose as a retarding agent to control the release rate and magnesium stearate as an inert dispersing carrier to decrease the interfacial tension between lipophilic and hydrophilic phase. Results: Prepared microcapsules were evaluated for the particle size, percentage yield, drug entrapment efficiency, flow property and in vitro drug release for 12 h. Results indicated that the percentage yield, mean particle size, drug entrapment efficiency and the micrometric properties of the microcapsules was influenced by various drug: polymer ratio. The release rate of microcapsules could be controlled as desired by adjusting the combination ratio of dispersing agents to retarding agents.Conclusion:Perindopril microcapsules can be successfully designed to develop sustained drug delivery, that reduces the dosing frequency and their by one can increase the patient compliance.

scholarly journals Indication of the Coronavirus Model Using a Nanowire Biosensor

Proceedings ◽  
2020 ◽  
Vol 60 (1) ◽  
pp. 50
Author(s):  
Vladimir Generalov ◽  
Olga Naumova ◽  
Dmitry Shcherbakov ◽  
Alexander Safatov ◽  
Boris Zaitsev ◽  
...  
Keyword(s):  
Field Effect ◽  
Field Effect Transistor ◽  
Negative Charge ◽  
Positive Charge ◽  
Silicon On Insulator ◽  
Nanowire Surface ◽  
Before And After ◽  
Effect Transistor ◽  
Current Value ◽  
Silicon On Insulator Technology

The presented results indicate virus-like particles of the coronavirus (CVP) using a nanowire (NW) biosensor based on silicon-on-insulator technology. In the experiment, we used suspensions of CVP and of specific antibodies to the virus. Measurements of the current value of the field-effect transistor before and after the introduction of the CVP on the surface of the nanowire were performed. Results showed antibody + CVP complexes on the phase section with the surface of the nanowire modulate the current of the field-effect transistor; CVP has an electrically positive charge on the phase section “nanowire surface-viral suspension»; antibody + CVP complexes have an electrically negative charge on the phase section “nanowire surface-viral suspension”; the sensitivity of the biosensor is made up of 10−18 M; the time display was 200–300 s.

scholarly journals The mechanism of spray electrification: the waterfall effect

2016 ◽  
Author(s):  
James K. Beattie
Keyword(s):  
Negative Charge ◽  
Positive Charge ◽  
Hydrophobic Hydration ◽  
General Phenomenon ◽  
Aqueous Interfaces ◽  
Preferential Adsorption ◽  
Negative Surface ◽  
Negative Surface Charge ◽  
Low Permittivity ◽  
Net Positive Charge

Abstract. The waterfall effect describes the separation of charge by splashing at the base of a waterfall. Smaller drops that have a net negative charge are created, while larger drops and/or the bulk maintain overall charge neutrality with a net positive charge. Since it was first described by Lenard (1892) the effect has been confirmed many times, but a molecular explanation has not been available. Application of our fluctuation-correlation model of hydrophobic hydration accounts for the negative charge observed at aqueous interfaces with low permittivity materials. The negative surface charge observed in the waterfall effect is created by the preferential adsorption of hydroxide ions generated from the autolysis of water. On splashing, shear forces generate small negative drops from the surface, leaving a positive charge on the remaining large fragment. The waterfall effect is a manifestation of the general phenomenon of the negative charge at the interface between water and hydrophobic surfaces that is created by the preferential adsorption of hydroxide ions.

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.

Electrokinetic properties of Cassiterite

1953 ◽  
Vol 6 (3) ◽  
pp. 278 ◽  
Author(s):  
DJ O'Connor ◽  
AS Buchanan
Keyword(s):  
Negative Charge ◽  
Positive Charge ◽  
Weak Acid ◽  
Surface Conductivity ◽  
Surface Ionization ◽  
Conductivity Measurements ◽  
The Third ◽  
Three Samples ◽  
Negative Surface ◽  
Flotation Collector

Simultaneous ζ-potential and surface conductivity measurements have been made on three samples of cassiterite (SnO2) in water, in solutions of HCl, alkalis, inorganic salts, and the flotation collector reagent sodium cetyl sulphate. It is probable that the intrinsic surface charge of cassiterite in water is negative and that it is due to surface ionization as a very weak acid. Two of the solids possessed a negative surface whilst the positive charge of the third seemed to be due to ionization of a strongly basic impurity. Those samples having a negative charge showed little reaction with sodium cetyl sulphate alone, but appreciable adsorption of cetyl sulphate ion took place in acid solution. On the other hand, the sample with the positive surface reacted with cetyl sulphate ion even in the absence of acid. In all cases adsorption of cetyl sulphate was completely reversible.

scholarly journals Electrical and Polarimetric Radar Observations of a Multicell Storm in TELEX

2007 ◽  
Vol 135 (7) ◽  
pp. 2525-2544 ◽  
Author(s):  
Eric C. Bruning ◽  
W. David Rust ◽  
Terry J. Schuur ◽  
Donald R. MacGorman ◽  
Paul R. Krehbiel ◽  
...  
Keyword(s):  
Electric Field ◽  
Electric Fields ◽  
Negative Charge ◽  
Positive Charge ◽  
Three Dimensional ◽  
Phase Region ◽  
Polarimetric Radar ◽  
Radar Observations ◽  
Mapping Array ◽  
Lightning Initiation

Abstract On 28–29 June 2004 a multicellular thunderstorm west of Oklahoma City, Oklahoma, was probed as part of the Thunderstorm Electrification and Lightning Experiment field program. This study makes use of radar observations from the Norman, Oklahoma, polarimetric Weather Surveillance Radar-1988 Doppler, three-dimensional lightning mapping data from the Oklahoma Lightning Mapping Array (LMA), and balloon-borne vector electric field meter (EFM) measurements. The storm had a low flash rate (30 flashes in 40 min). Four charge regions were inferred from a combination of LMA and EFM data. Lower positive charge near 4 km and midlevel negative charge from 4.5 to 6 km MSL (from 0° to −6.5°C) were generated in and adjacent to a vigorous updraft pulse. Further midlevel negative charge from 4.5 to 6 km MSL and upper positive charge from 6 to 8 km (from −6.5° to −19°C) were generated later in quantity sufficient to initiate lightning as the updraft decayed. A negative screening layer was present near the storm top (8.5 km MSL, −25°C). Initial lightning flashes were between lower positive and midlevel negative charge and started occurring shortly after a cell began lofting hydrometeors into the mixed phase region, where graupel was formed. A leader from the storm’s first flash avoided a region where polarimetric radar suggested wet growth and the resultant absence of noninductive charging of those hydrometeors. Initiation locations of later flashes that propagated into the upper positive charge tracked the descending location of a polarimetric signature of graupel. As the storm decayed, electric fields greater than 160 kV m−1 exceeded the minimum threshold for lightning initiation suggested by the hypothesized runaway breakdown process at 5.5 km MSL, but lightning did not occur. The small spatial extent (≈100 m) of the large electric field may not have been sufficient to allow runaway breakdown to fully develop and initiate lightning.

The influence of organic matter extracted from humified clover on the properties of amorphous aluminosilicates. I. Surface charge

Soil Research ◽  
1978 ◽  
Vol 16 (3) ◽  
pp. 327 ◽  
Author(s):  
KW Perrott
Keyword(s):  
Surface Charge ◽  
Negative Charge ◽  
Positive Charge ◽  
Degree Of Polymerization ◽  
Aqueous Extracts ◽  
Hydrous Oxides ◽  
Soil Clays ◽  
Charge Balancing ◽  
Inorganic Components ◽  
Allophanic Soil

A series of synthetic amorphous aluminosilicates, hydrous oxides and allophanic soil clays were treated with aqueous extracts of humified clover. The resulting changes in surface charge due to organic treatment were determined by comparing the charge characteristics of these organic treated samples and samples treated with a synthetic mixture of the inorganic components of the humified clover extract. Organic treatment caused a change of net surface charge to more negative values. The change in surface charge varied with the mole ratio Al/(Al+Si) of the aluminosilicate, being largest at low values of Al/(Al+Si). Where the aluminosilicates contain positive charges these are reduced by the organic treatment. This is a major contributor to the alteration of net surface charge in the more aluminous samples. The effect of organic treatment on the charge characteristics of allophanic soil clays was similar to that for the synthetic aluminosilicates of intermediate composition. The inorganic treatments also caused an increase in negative charge, and this is attributed to the neutralization of positive charge by the adsorption of phosphate and the removal of charge-balancing aluminium-hydroxy material. The effect of the organic and inorganic treatments on the positive and negative charge components of amorphous aluminosilicates is discussed in terms of the degree of polymerization of chargebalancing hydroxy-aluminium as envisaged in current models of the structure of amorphous aluminosilicates.

scholarly journals C5-Substituted 2-Selenouridines Ensure Efficient Base Pairing with Guanosine; Consequences for Reading the NNG-3′ Synonymous mRNA Codons

2020 ◽  
Vol 21 (8) ◽  
pp. 2882 ◽  
Author(s):  
Grazyna Leszczynska ◽  
Marek Cypryk ◽  
Bartlomiej Gostynski ◽  
Klaudia Sadowska ◽  
Paulina Herman ◽  
...  
Keyword(s):  
Gene Expression ◽  
Density Functional ◽  
Negative Charge ◽  
Positive Charge ◽  
Dominant Role ◽  
Regulation Of Gene Expression ◽  
Side Chain ◽  
Functional Theory ◽  
Physiological Conditions ◽  
Synonymous Codons

5-Substituted 2-selenouridines (R5Se2U) are post-transcriptional modifications present in the first anticodon position of transfer RNA. Their functional role in the regulation of gene expression is elusive. Here, we present efficient syntheses of 5-methylaminomethyl-2-selenouridine (1, mnm5Se2U), 5-carboxymethylaminomethyl-2-selenouridine (2, cmnm5Se2U), and Se2U (3) alongside the crystal structure of the latter nucleoside. By using pH-dependent potentiometric titration, pKa values for the N3H groups of 1–3 were assessed to be significantly lower compared to their 2-thio- and 2-oxo-congeners. At physiological conditions (pH 7.4), Se2-uridines 1 and 2 preferentially adopted the zwitterionic form (ZI, ca. 90%), with the positive charge located at the amino alkyl side chain and the negative charge at the Se2-N3-O4 edge. As shown by density functional theory (DFT) calculations, this ZI form efficiently bound to guanine, forming the so-called “new wobble base pair”, which was accepted by the ribosome architecture. These data suggest that the tRNA anticodons with wobble R5Se2Us may preferentially read the 5′-NNG-3′ synonymous codons, unlike their 2-thio- and 2-oxo-precursors, which preferentially read the 5′-NNA-3′ codons. Thus, the interplay between the levels of U-, S2U- and Se2U-tRNA may have a dominant role in the epitranscriptomic regulation of gene expression via reading of the synonymous 3′-A- and 3′-G-ending codons.

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