scholarly journals The Effects of Ethanol Concentration and of Ionic Strength on the Zeta Potential of Titania in the Presence of Sodium Octadecyl Sulfate

2020 ◽  
Vol 4 (4) ◽  
pp. 49
Author(s):  
Marek Kosmulski ◽  
Edward Mączka
Keyword(s):  
Ionic Strength ◽  
Zeta Potential ◽  
Metal Oxides ◽  
Ethanol Concentration ◽  
Ionic Surfactants ◽  
Nacl Concentration ◽  
Sodium Alkyl Sulfates ◽  
Alkyl Sulfates ◽  
Low Solubility ◽  
Negative Zeta Potential

Sodium octadecyl sulfate (C18H37SO4Na) induces a negative zeta potential of metal oxides at very low surfactant concentrations as compared with shorter-chained sodium alkyl sulfates. The problem of low solubility of sodium octadecyl sulfate in water was solved by the addition of the surfactant to dispersions as ethanolic stock solution, but then the presence of ethanol in dispersions was inevitable. We demonstrate that the concentration of ethanol (up to 5% by mass) in a dispersion containing titania (TiO2) and sodium octadecyl sulfate has an insignificant effect on the zeta potential of particles. We further demonstrate that the shifts in the IEP of titania induced by the presence of sodium octadecyl sulfate are independent of the NaCl concentration. The results obtained in this study can be generalized for 1-1 salts other than NaCl, for metal oxides other than titania, for organic co-solvents other than ethanol, and for sparingly soluble ionic surfactants other than sodium octadecyl sulfate.

scholarly journals Microparticle Deposition on Human Serum Albumin Layers: Unraveling Anomalous Adsorption Mechanism

2020 ◽  
Vol 4 (4) ◽  
pp. 51
Author(s):  
Małgorzata Nattich-Rak ◽  
Maria Dąbkowska ◽  
Zbigniew Adamczyk
Keyword(s):  
Ionic Strength ◽  
Human Serum Albumin ◽  
Zeta Potential ◽  
Serum Albumin ◽  
Human Serum ◽  
Electrostatic Interactions ◽  
Surface Concentration ◽  
Dlvo Theory ◽  
Adsorption Model ◽  
Negative Zeta Potential

Human serum albumin (HSA) layers are adsorbed on mica under controlled diffusion transport at pH 3.5 and various ionic strengths. The surface concentration of HSA is directly determined by AFM imaging of single molecules. It is shown that the adsorption kinetics derived in this way is quantitatively described using the random sequential (RSA) adsorption model. The electrokinetic characteristics of the HSA layers at various pHs comprising their zeta potential are acquired in situ while using the streaming potential method. It is shown that at pH 3.5 the zeta potential of mica becomes positive for HSA concentrations above 3000 μm−2. At larger pHs, HSA layers exhibit negative zeta potential for the entire range of coverage. Thorough characteristics of these monolayers at various pHs were performed applying the colloid deposition method involving negatively charged polystyrene microparticles. The kinetics of their deposition and their maximum coverage are determined as a function of the HSA layer surface concentration, pH, and ionic strength. An anomalous deposition of microparticles on substrates also exhibiting a negative zeta potential is observed, which contradicts the Derjaguin, Landau, Vervey, Overbeek (DLVO) theory. This effect is interpreted in terms of heterogeneous charge distribution that results from molecule concentration fluctuations. It is also shown that the maximum concentration of microparticles abruptly decreases with the electric double-layer thickness that is regulated by changing ionic strength, which indicates that their deposition is governed by electrostatic interactions. One can argue that the results obtained in this work can be exploited as useful reference data for the analysis of deposition phenomena of bioparticles on protein layers.

scholarly journals The Isoelectric Point of an Exotic Oxide: Tellurium (IV) Oxide

Molecules ◽  
2021 ◽  
Vol 26 (11) ◽  
pp. 3136
Author(s):  
Marek Kosmulski ◽  
Edward Mączka
Keyword(s):  
Zeta Potential ◽  
Metal Oxides ◽  
Isoelectric Point ◽  
Inorganic Ions ◽  
Ionic Surfactants ◽  
Surface Charging ◽  
Ph Dependent ◽  
Ph Range

The pH-dependent surface charging of tellurium (IV) oxide has been studied. The isoelectric point (IEP) of tellurium (IV) oxide was determined by microelectrophoresis in various 1-1 electrolytes over a concentration range of 0.001–0.1 M. In all electrolytes studied and irrespective of their concentration the zeta potential of TeO2 was negative over the pH range 3–12. In other words the IEP of TeO2 is at pH below 3 (if any). TeO2 specifically adsorbs ionic surfactants, and their presence strongly affects the zeta potential. In contrast the effect of multivalent inorganic ions on the zeta potential of TeO2 is rather insignificant (no shift in the IEP). In this respect TeO2 is very different from metal oxides.

Artemisinin (ART) Drug Delivery Using Mixed Non-ionic Surfactants and Evaluation of Their Efficiency in Different Cancer Cell Lines

2017 ◽  
Vol 4 (4) ◽  
Author(s):  
Elnaz Asgharkhani ◽  
Aazam Najmafshar ◽  
Mohsen Chiani
Keyword(s):  
Zeta Potential ◽  
Cell Line ◽  
Mtt Assay ◽  
Therapeutic Index ◽  
Stability Study ◽  
Polydispersity Index ◽  
Ionic Surfactants ◽  
Cytotoxicity Test ◽  
Molar Ratios ◽  
Chemotherapy Agent

This study aims to investigate the effects of different non-ionic surfactants on physicochemical properties of ART niosomes. ART is a natural compound that is used as an antimalarial and chemotherapy agent in medicine. ART has low bioavailability, stability and solubility. In order to solve these problems and enhancing the efficiency of the drug, nanotechnology was used. In the present study, several niosomal formulations of ART prepared using different molar ratios of Span 60 : Tween 60 : PEG-600: ART in PBS. These three formulations were FI (1:1:0.5:0.5), FII (2:1:0.5:0.5) and FIII (1:2:0.5:0.5), respectively. The encapsulation efficiency was measured by HPLC and the drug release was evaluated by dialysis method. The cytotoxicity test was determined by MTT assay. The size, zeta potential and polydispersity index of the vesicles was measured by Zeta Sizer. Stability study was performed within two months. The MTT assay results showed that cytotoxicity effect of these formulations on MCF-7 cell line is better than C6 cell line and the FIII had the best results for both of them. The entrapment efficiencies of the formulations I, II and III were obtained 82.2±1.88%, 75.5±0.92% and 95.5±1.23%, respectively. The results of size, zeta potential and polydispersity index indicated that the size of the vesicles is below 200 nm, their surface charge is about -35 mV and they were monodisperse. Stability and release study indicated that the formulation III has the best stability and release pattern. Therefore, the use of PEGylated niosomal ART can effectively improve its therapeutic index, stability and solubility.

Influence of Surface Zeta Potential on Adhesion of Chlorella sp. to Substratum Surfaces

2013 ◽  
Vol 690-693 ◽  
pp. 1431-1434
Author(s):  
Xin Ru Zhang ◽  
Ze Yi Jiang ◽  
Hao Yuan ◽  
Yuan Xiang Lu ◽  
Liang Chen ◽  
...  
Keyword(s):  
Zeta Potential ◽  
Cell Surface ◽  
Mass Culture ◽  
Chlorella Sp ◽  
Microalgae Mass Culture ◽  
Negative Zeta Potential

Microalgae, in wet conditions, tend to grow on surfaces and form biofilms. The adhesion of microalgae to surfaces is very important for algal mass culture. The formation and development of microalgal biofims are in large denpend on the properties of cell surface, substratum surface and gowth medium. In this paper, the influence of substratum surface zeta potential on the microalgal biofilms was particularly investigated. We focused on a widely-used microalgal strain, the freshwater autotrophicChlorella sp..The adhesion phenomena ofChlorella sp.to surfaces with different zeta potential were observed microscopically. It was found thatChlorella sp.adhered easily to the surface with a positive zeta potential and difficultly to the surface with a negative zeta potential. We concluded that the surface zeta potential had a greater influence on the adhesion of microalgal cells to substratum surfaces. Our findings have important implications for microalgae mass culture and harvesting.

Sodium alkyl sulfates as maximum suppressors

1972 ◽  
Vol 40 (2) ◽  
pp. 419-429 ◽  
Author(s):  
Vinay Kumar ◽  
T.W. Gilbert
Keyword(s):  
Sodium Alkyl Sulfates ◽  
Alkyl Sulfates

scholarly journals Electroosmotic Flow Hysteresis for Fluids with Dissimilar pH and Ionic Species

Micromachines ◽  
2021 ◽  
Vol 12 (9) ◽  
pp. 1031
Author(s):  
An Eng Lim ◽  
Yee Cheong Lam
Keyword(s):  
Zeta Potential ◽  
Electroosmotic Flow ◽  
Flow Direction ◽  
Velocity Model ◽  
Ionic Species ◽  
Dependent Behavior ◽  
Nacl Concentration ◽  
Solution Pair ◽  
Current Monitoring ◽  
Ion Species

Electroosmotic flow (EOF) involving displacement of multiple fluids is employed in micro-/nanofluidic applications. There are existing investigations on EOF hysteresis, i.e., flow direction-dependent behavior. However, none so far have studied the solution pair system of dissimilar ionic species with substantial pH difference. They exhibit complicated hysteretic phenomena. In this study, we investigate the EOF of sodium bicarbonate (NaHCO3, alkaline) and sodium chloride (NaCl, slightly acidic) solution pair via current monitoring technique. A developed slip velocity model with a modified wall condition is implemented with finite element simulations. Quantitative agreements between experimental and simulation results are obtained. Concentration evolutions of NaHCO3–NaCl follow the dissimilar anion species system. When NaCl displaces NaHCO3, EOF reduces due to the displacement of NaHCO3 with high pH (high absolute zeta potential). Consequently, NaCl is not fully displaced into the microchannel. When NaHCO3 displaces NaCl, NaHCO3 cannot displace into the microchannel as NaCl with low pH (low absolute zeta potential) produces slow EOF. These behaviors are independent of the applied electric field. However, complete displacement tends to be achieved by lowering the NaCl concentration, i.e., increasing its zeta potential. In contrast, the NaHCO3 concentration has little impact on the displacement process. These findings enhance the understanding of EOF involving solutions with dissimilar pH and ion species.

Enhanced growth and matrix production by human osteoblastic cells cultured on biomaterials with negative zeta potential

Bone ◽  
2009 ◽  
Vol 44 ◽  
pp. S259 ◽  
Author(s):  
J.P. Dillon ◽  
P.J.M. Wilson ◽  
W.D. Fraser ◽  
B.K. Mwaura ◽  
M.J. Hayton ◽  
...  
Keyword(s):  
Zeta Potential ◽  
Osteoblastic Cells ◽  
Matrix Production ◽  
Human Osteoblastic Cells ◽  
Negative Zeta Potential ◽  
Cells Cultured

Effect of Different Anions on 22Na Permeability of Liposomes

1973 ◽  
Vol 51 (11) ◽  
pp. 779-784 ◽  
Author(s):  
M. A. Singer
Keyword(s):  
Zeta Potential ◽  
Dipole Potential ◽  
Sodium Permeability ◽  
Phosphatidylcholine Liposomes ◽  
Solution Interface ◽  
Cation Permeability ◽  
Na Efflux ◽  
Negative Zeta Potential

The 22Na efflux from phosphatidylcholine liposomes was measured in the presence of different anions. Only salicylate significantly increases sodium permeability. Although this anion adsorbs onto the liposomal surface creating a negative zeta potential, evidence is presented that this is not the sole mechanism underlying the enhanced cation permeability. It is proposed that salicylate also alters the dipole potential at the membrane–solution interface.

Bioleaching Solutions Used for the Nanoparticles Biosynthesis for Uranium and Arsenic Immobilization

2020 ◽  
Vol 304 ◽  
pp. 45-50
Author(s):  
Agnieszka Pawlowska ◽  
Zygmunt Sadowski
Keyword(s):  
Zeta Potential ◽  
Solid Waste ◽  
Green Tea ◽  
Camellia Sinensis ◽  
Plant Extract ◽  
Uranium Dioxide ◽  
Electrical Potential ◽  
Nanoparticle Synthesis ◽  
Negative Zeta Potential

Bioleaching solutions from uranium and arsenic solid waste served as a source of U(VI) and As (V) ions, while plant extract from green tea (Camellia sinensis) – as a reductor for nanoparticle synthesis. Uranium dioxide and As (III) nanoparticles were formed as a product of bioreduction on the hematite and schwertmannite surfaces respectively, which resulted in an increase in the negative zeta potential with an increase in pH. It suggests, that the electrical potential depends on the presence of nanoparticles. The SEM microphotographs revealed the UO2 nanoparticles on the hematite surface.

scholarly journals Dispersions of Metal Oxides in the Presence of Anionic Surfactants

2018 ◽  
Vol 3 (1) ◽  
pp. 3 ◽  
Author(s):  
Leszek Ruchomski ◽  
Edward Mączka ◽  
Marek Kosmulski
Keyword(s):  
Metal Oxides ◽  
Surfactant Concentration ◽  
Critical Concentration ◽  
Supporting Electrolyte ◽  
Sodium Dodecyl ◽  
Sodium Dodecylsulfate ◽  
Solubility Limit ◽  
Ionic Surfactants ◽  
Liquid Ratio ◽  
High Concentration

We studied the behavior of dilute dispersions of nanoparticles of hematite, alumina, and titania in the presence of various concentrations of very pure sodium dodecyl-, tetradecyl-, and hexadecylsulfate. The concentrations studied were up to critical micelle concentration (CMC) for sodium dodecylsulfate, and up to the solubility limit in case of sodium tetradecyl- and hexadecylsulfate. The dispersions were adjusted to different pH (3–11), and 10−3 M NaCl was used as the supporting electrolyte. The solid-to-liquid ratio was strictly controlled in all dispersions, and the behavior of fresh dispersions was compared with dispersions aged for up to eight days. The presence of very low concentrations of ionic surfactants had rather insignificant effects on the ζ potentials of the particles. At sufficient concentrations of ionic surfactants the isoelectric point (IEP) of metal oxides shifted to low pH, and the long-chain surfactants were more efficient in shifting the IEP than their shorter-chain analogues. Once the surfactant concentration reached a critical value, the ζ potentials of the particles reached a pH-independent negative value, which did not change on further increase in the surfactant concentration and/or aging of the dispersion. This critical concentration increases with the solid-to-liquid ratio, and it is rather consistent (for certain oxides and certain surfactants) when it is expressed as the amount of surfactant per unit of surface area. Surprisingly, the surfactant-stabilized dispersions always showed a substantial degree of aggregation; that is, the particle size observed in dispersions by dynamic light scattering was higher than the size of particles observed in dry powders by electron microscopy. Apparently, in spite of relatively high ζ potentials (about 60 mV in absolute value), the surfactant-stabilized dispersions consist of aggregates rather than of primary particles, and in certain dispersions the high concentration of surfactant seems to induce aggregation rather than prevent it.

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