Temperature- and ionic strength-induced conformational changes in the lipid head group region of liposomes as suggested by zeta potential data

Correction for ‘Effect of lipid head group interactions on membrane properties and membrane-induced cationic β-hairpin folding’ by Sai J. Ganesan et al., Phys. Chem. Chem. Phys., 2016, 18, 17836–17850.

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Surface contraction of dividing newt eggs induced by lowering the external ionic strength or pH, or by trypsinization

Journal of Cell Science ◽

10.1242/jcs.82.1.143 ◽

1986 ◽

Vol 82 (1) ◽

pp. 143-154

Author(s):

T. Kubota

Keyword(s):

Ionic Strength ◽

Conformational Changes ◽

Time Course ◽

Similar Type ◽

Vitelline Membrane ◽

Common Mechanism ◽

Surface Material ◽

Sucrose Medium ◽

Saline Medium ◽

Partial Reversal

As the first cleavage progresses, newt (Cynopus pyrrhogaster) eggs deprived of their vitelline membrane grow to expose the new, unpigmented surface to a saline medium full-strength Steinberg solution). Further exposure of these eggs to sucrose medium resulted in rapid and extensive contraction of the unpigmented surface. In the sucrose medium the contraction continued until the next cleavage, and eventually the eggs divided into many blastomeres. But partial reversal of the contraction was observed when, after brief treatment with sucrose medium, the eggs were returned to saline medium. This and other experiments indicated that the contraction was due to lowering of the extracellular ionic strength. A similar type of contraction was induced by acidification of the saline medium or by trypsinization. The contractions induced by these treatments did not absolutely require the presence of external Ca2+, had a rapid time course, and were restricted to the unpigmented region, suggesting that they had a common mechanism. Acidification of the egg cytoplasm with CO2 did not result in significant contraction. These findings, together with those of others, suggest that contraction of the unpigmented surface induced by these treatments is due to conformational changes of surface material.

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New Opportunity to Formulate Intranasal Vaccines and Drug Delivery Systems Based on Chitosan

International Journal of Molecular Sciences ◽

10.3390/ijms21145016 ◽

2020 ◽

Vol 21 (14) ◽

pp. 5016

Author(s):

Roxana Popescu ◽

Mihaela Violeta Ghica ◽

Cristina-Elena Dinu-Pîrvu ◽

Valentina Anuța ◽

Dumitru Lupuliasa ◽

...

Keyword(s):

Drug Delivery ◽

Surface Tension ◽

Zeta Potential ◽

Conformational Changes ◽

Drug Delivery Systems ◽

Delivery Systems ◽

Active Pharmaceutical Ingredients ◽

Nasal Drug Delivery ◽

Pharmaceutical Ingredients ◽

Permeability Enhancement

In an attempt to develop drug delivery systems that bypass the blood–brain barrier (BBB) and prevent liver and intestinal degradation, it was concluded that nasal medication meets these criteria and can be used for drugs that have these drawbacks. The aim of this review is to present the influence of the properties of chitosan and its derivatives (mucoadhesion, permeability enhancement, surface tension, and zeta potential) on the development of suitable nasal drug delivery systems and on the nasal bioavailability of various active pharmaceutical ingredients. Interactions between chitosan and proteins, lipids, antigens, and other molecules lead to complexes that have their own applications or to changing characteristics of the substances involved in the bond (conformational changes, increased stability or solubility, etc.). Chitosan and its derivatives have their own actions (antibacterial, antifungal, immunostimulant, antioxidant, etc.) and can be used as such or in combination with other molecules from the same class to achieve a synergistic effect. The applicability of the properties is set out in the second part of the paper, where nasal formulations based on chitosan are described (vaccines, hydrogels, nanoparticles, nanostructured lipid carriers (NLC), powders, emulsions, etc.).

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How Transmembrane Model Peptides Affect Lipid Head Group Orientation: An Application of 14N NMR

Biophysical Journal ◽

10.1016/j.bpj.2010.12.3669 ◽

2011 ◽

Vol 100 (3) ◽

pp. 638a-639a ◽

Cited By ~ 1

Author(s):

Jacques P.F. Doux ◽

Benjamin A. Hall ◽

J. Antoinette Killian

Keyword(s):

Head Group ◽

Group Orientation ◽

Lipid Head Group ◽

14N Nmr ◽

Model Peptides

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The Effect of the Ionic Strength of Process Water on the Interaction of Talc and CMC: Implications of Recirculated Water on Floatable Gangue Depression

Minerals ◽

10.3390/min9040231 ◽

2019 ◽

Vol 9 (4) ◽

pp. 231 ◽

Cited By ~ 2

Author(s):

Malibongwe Manono ◽

Kirsten Corin ◽

Jenny Wiese

Keyword(s):

Ionic Strength ◽

Zeta Potential ◽

Saline Water ◽

Process Water ◽

Gangue Mineral ◽

Mineral Surface ◽

Base Interaction ◽

Long Run ◽

Complex Process ◽

Closed Water

Previous studies speculate that hydroxo species present in flotation pulps at pH > 9, particularly those of polyvalent cations, selectively adsorb onto gangue minerals. Such species supposedly enhance the depressive action of carboxymethyl cellulose (CMC) onto gangue via an acid-base interaction between the positively charged mineral surface and the negatively charged CMC molecule. Thus, the hydrophilicity of gangue minerals is enhanced, preventing the dilution of the concentrate. However, as there is little evidence to support these claims for complex process waters of increasing ionic strength, it is important to investigate. Adsorption data and mineral surface charge analyses provide a fundamental understanding of how electrolytes and their ionic strengths affect gangue mineral-depressant adsorption. It is strongly anticipated that decoupling these effects will allow process operators to tailor their process water quality needs towards best flotation operating regimes and, in the long run, effect closed water circuits. Thus, using talc as a proxy for naturally floatable gangue common in sulfidic Cu–Ni–PGM ores, this work investigates the influence of the ionic strength of process water on the adsorption of CMC onto talc for a perspective on how saline water in sulfidic ores would affect the behavior and therefore management of floatable gangue. In the presence of CMC, the microflotation results showed that the rate of talc recovery decreased with increasing ionic strength of process water. Increases in ionic strength resulted in an increase in the adsorption of CMC onto talc. Talc particles proved to have been more coagulated at higher ionic strength since the settling time decreased with increasing ionic strength. Furthermore, the zeta potential of talc particles became less negative at higher ionic strengths of process water. It is thus proposed that increases in the ionic strength of process water increased the zeta potential of talc particles, enhancing the adsorption of CMC onto talc. This in turn created a more coagulated nature on talc particles, increasing their hydrophilicity and thereby retarding floatability.

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