Download or read book The Effect of Nonionic Surfactant Micelles Or Microemulsions on Brush Border Membranes written by Merav Edan and published by . This book was released on 1993 with total page 250 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Micelles Membranes Microemulsions and Monolayers written by William M. Gelbart and published by Springer Science & Business Media. This book was released on 2012-12-06 with total page 620 pages. Available in PDF, EPUB and Kindle. Book excerpt: Over the last decades, the study of surfactants (detergents, for example) has been profoundly changed by ideas and techniques from physics, chemistry, and materials science. Among these are: self assembly; critical phenomena, scaling, and renormalization; high-resolution scattering, and magnetic resonance spectroscopy. This book represents the first systematic account of these new developments, providing both a general introduction to the subject as well as a review of recent developments. The book will be a very useful tool for the biophysist, biochemist or physical chemist working in the field of surfactants.
Download or read book Role of Nonionic Surfactants in Promoting the Folding and Stability of Integral Membrane Proteins written by Carolina Bianco and published by ProQuest. This book was released on 2008 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Membrane proteins are characterized by their extensive hydrophobic surface area designed to interact with the lipid bilayer. These proteins provide functionality to the cell membrane by stabilizing this interface, acting as selective transporters and receptors. Because of their central role in communications between the cell and its environment, membrane proteins are common targets for pharmaceuticals. Nonionic surfactants are commonly used amphiphiles that can serve to shield the hydrophobic surface area of membrane proteins and allow their solubilization in aqueous solutions, resulting in the formation of protein-detergent complexes. The ideal surfactant is able to maintain the physiological function and structure of a target membrane protein in solution, therefore preventing unfolding and aggregation. Currently, trial and error is necessary to determine the best nonionic surfactant for each membrane protein target. This thesis focuses on the role of nonionic surfactants in the folding and stability of integral membrane proteins. Two points of view are considered: the role of the surfactant in establishing and stabilizing the protein structure, and the morphology and interactions of protein-detergent complexes. The main integral membrane protein under consideration was the outer membrane protein X, ompX, from E. coli, and its interactions were studied with polyoxyethylene nonionic surfactants noctyltetraoxyethylene (C 8 E 4), n-octylpentaoxyethylene, (C 8 E 5), n-dodecylhexaoxyethylene (C 12 E 6) and n-dodecyloctaoxyethylene (C 12 E 8). OmpX production was achieved through recombinant inclusion body expression in its native host, followed by purification in a denatured conformation. A rapid dilution refolding protocol was developed and was applied to compare the refolding of ompX in various nonionic surfactants. The final protein structure was determined from circular dichroism, fluorescence and FTIR spectroscopy analyses. The secondary structure of ompX was found to be very similar in all surfactants studied, and comparable to the estimates from its NMR structure and from the secondary structure of other refolded outer membrane proteins. Nonionic surfactants self-assemble into micelles in aqueous solutions at concentrations above the critical micelle concentration (CMC). Solutions of nonionic surfactants at concentrations above their CMC may display a phase separation with increasing temperature. The lowest temperature at which this separation can be detected is called the cloud point temperature (CPT). As the CPT is approached, micelle interactions can be considered to become more attractive or their morphology to become more elongated. In the process of understanding how surfactants can stabilize integral membrane proteins, it was necessary to examine how the chaotropic agent urea, commonly used in protein unfolding studies, affects surfactant phase behavior. Urea was found to increase the CMC of all polyoxyethylene surfactants studied significantly, as well as increase their CPT. The effect of urea on micelle morphology and interaction was probed by small-angle neutron scattering (SANS) experiments. It was found that micelles of C 8 E 4 and C 12 E 6 appeared elongated without urea in solution and become globular with increasing urea concentration. This effect was absent for C 8 E 5 and C 12 E 8 micelles, which remained globular independent of urea concentration. Therefore, we suggest an analogy between the effect of increasing urea concentration and decreasing temperature on the phase behavior of polyoxyethylene surfactants. The ability of nonionic surfactants to stabilize ompX in solution was tested by unfolding the PDC by increasing the urea concentration. Loss of protein structure was monitored by circular dichroism and fluorescence spectroscopies. Surfactant type and concentration were found to influence ompX unfolding. The protein stability was greatly diminished if the surfactant concentration fell below the CMC compared to when the surfactant concentration was adjusted to account for CMC changes with increasing urea concentration. The interactions and morphologies of ompX PDCs in solution with micelles of C 8 E 4, C 8 E 5, C 12 E 6 and C 12 E 8 surfactants with increasing urea concentration were examined by SANS. The challenge of these experiments was to distinguish the scattering of PDCs from that of micelles. Differences between the two sets of scattering curves are most prominent at urea concentrations below 2 M, and become small at urea concentrations at which ompX is denatured. These differences are more prominent in C 8 surfactants at 0 and 2 M urea, which contain elongated particles interpreted as aggregated PDCs. Simple models were applied to analyze the scattering of solutions containing PDCs and micelles but were unable to capture the entire scattering curves within physically realistic parameter constraints.
Download or read book Surfactants in Solution written by Arun K. Chattopadhyay and published by CRC Press. This book was released on 2020-08-26 with total page 434 pages. Available in PDF, EPUB and Kindle. Book excerpt: Contains selected invited papers presented at the 10th International Symposium on Surfactants in Solution held in Caracas, Venezuela. The volume covers phase behaviour of monolayers, contact angle hysteresis, micellar relaxation, micellar catalyzed reactions, polymerization in microemulsions, polymer-surfactant complexation, asphaltenes, and more.
Download or read book Water Insoluble Drug Formulation written by Ron Liu and published by CRC Press. This book was released on 2018-03-12 with total page 781 pages. Available in PDF, EPUB and Kindle. Book excerpt: Properties and Formulation: From Theory to Real-World Application Scientists have attributed more than 40 percent of the failures in new drug development to poor biopharmaceutical properties, particularly water insolubility. Issues surrounding water insolubility can postpone or completely derail important new drug development. Even the much-needed reformulation of currently marketed products can be significantly affected by these challenges. More recently it was reported that the percentage increased to 90% for the candidates of new chemical entities in the discovery stage and 75% for compounds under development. In the most comprehensive resource on the topic, this third edition of Water-Insoluble Drug Formulation brings together a distinguished team of experts to provide the scientific background and step-by-step guidance needed to deal with solubility issues in drug development. Twenty-three chapters systematically describe the detailed discussion on solubility theories, solubility prediction models, the aspects of preformulation, biopharmaceutics, pharmacokinetics, regulatory, and discovery support of water-insoluble drugs to various techniques used in developing delivery systems for water-insoluble drugs. This book includes more than 15 water-insoluble drug delivery systems or technologies, illustrated with case studies and featuring oral and parenteral applications. Highlighting the most current information and data available, this seminal volume reflects the significant progress that has been made in nearly all aspects of this field. The aim of this book is to provide a handy reference for pharmaceutical scientists in the handling of formulation issues related to water-insoluble drugs. In addition, this book may be useful to pharmacy and chemistry undergraduate students and pharmaceutical and biopharmaceutical graduate students to enhance their knowledge in the techniques of drug solubilization and dissolution enhancement.
Download or read book Nonionic Surfactants written by Martin J. Schick and published by . This book was released on 1967 with total page 1085 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Surfactants and Interfacial Phenomena written by Milton J. Rosen and published by Wiley-Interscience. This book was released on 1989 with total page 454 pages. Available in PDF, EPUB and Kindle. Book excerpt: The Second Edition has been updated to reflect recent advances in our knowledge of theory and practices. New applications run the gamut from microelectronics and magnetic recording, to biotechnology and nonconventional energy conversion. There is a new chapter on the interactions between surfactants. New sections have been added, and original sections expanded, on such topics as ultralow liquid-liquid interfacial tension, microemulsions, miniemulsions, and multiple emulsions, liquid crystal formation, hydrotropy, and steric forces in the stabilization of dispersions. There is also new material on lime soap dispersing agents, fabric softeners, adsorption and wetting of solid surfaces--both equilibrium and nonequilibrium, the relationship between adsorption and micellation in aqueous solutions and its effect on surface tension reduction, and factors determining micellar structure and shape.
Download or read book Transport in Complex Self assembled Surfactant Systems written by Wyatt Jacob Musnicki and published by . This book was released on 2012 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The purpose of this work is to advance the understanding of the diffusive transport of hydrophobic compounds (pharmaceuticals, nutraceuticals, flavors, pesticides, etc.) solubilized in microemulsions and the particles that carry them through solution and in fibrous media. The first focus of this research was to investigate the gradient-diffusion of charged anionic micelles in solution and a fibrous gel at moderate but dilute concentrations above the critical micelle concentration. Of particular interest were the effects of micelle, gel, and sodium chloride concentration on the micelle diffusivity. Holographic interferometry was used extensively to measure the micelle gradient-diffusion coefficient as a function of surfactant concentration at multiple sodium chloride and gel concentrations. The micelle diffusivity was shown to increase linearly with surfactant concentration at the two larger sodium chloride concentrations and all gel concentrations. In general, the strength of this effect increased with decreasing sodium chloride concentration and increased with gel concentration. This behavior is evidence of decreasing micelle-micelle electrostatic interactions with increasing sodium chloride concentrations, and increasing excluded volume effects and hydrodynamic screening with increasing gel concentration, respectively. The extrapolated, infinite-dilution diffusion coefficients and the rate at which the micelle diffusivity increased with surfactant concentration were compared with predictions of previously published theories in which the micelles are treated as charged, colloidal spheres and the gel as a Brinkman medium. The experimental data and theoretical predictions were in good agreement, particularly at the higher salt concentrations. The second focus of this work was to investigate the gradient-diffusion of hydrophobic compounds in microemulsions. Three solutes of increasing hydrophobicity were used and two different types of surfactants, one non-ionic and the other anionic, were investigated. The transport of the hydrophobic compounds within the microemulsions were tracked using holographic interferometry. For three of the solute-surfactant pairs, the measured interferometry patterns exhibited pseudo-binary features and the effective binary diffusion coefficient of the solutes was extracted from these patterns. The effective diffusion coefficient of one solute-surfactant pair was between the slowest diffusing component, the micelle, and the fastest diffusing component, the solute in water. The other measured effective diffusivities were either much smaller than the micelle diffusivity or much larger than the solute's diffusivity in water. For the remaining three solute-surfactant pairs, the interferometric patterns clearly demonstrated the transport of more than two components. For these, the effective binary diffusion coefficients could not be extracted. To improve on the pseudo-binary results and to account for the coupled transport of solute, a ternary multicomponent method was adapted for use with holographic interferometry. The ternary diffusivities: D11, D12, D21, and D22 were determined for all sets of solutes and surfactants. The value of D22 were found to be in all cases equal to the micelle diffusivity. The values of D11 were found to be less than the solute's diffusivity in water and to decrease as the solute's hydrophobicity increased. The values of D12 and D21 were found to depend in a complex manner with the solute's hydrophobicity and the type of surfactant used. Holographic interferometry was a useful tool for extracting complex information from the transport mechanisms of the solute and surfactant gradient-diffusion in micelles and microemulsions.
Download or read book The Effects of Non ionic Surfactants on Biological and Model Membrane Systems written by Hassan Mohamed Tahir Al-Assadi and published by . This book was released on 1988 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book The Effects of Non ionic Surfactants on Biological and Model Membrane Systems written by Al-Assadi Hassan Mohamed Tahir and published by . This book was released on 1988 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Chemical Abstracts written by and published by . This book was released on 2002 with total page 2616 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Surfactant Science written by Steven John Abbott and published by . This book was released on 2017 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: A concise and practical reference for understanding surfactant systems Offers original formulas and phase diagrams for improved surfactant design and performance¿ Equations related to online computer apps allow readers to test their own data Written in a conversational form, with a focus on real-world problems and troubleshooting Applications to detergents, coatings, cosmetics, soil and water remediation, and biosurfactants Full chapter included on foam and anti-foam science
Download or read book The Structure and Conformation of Amphiphilic Membranes written by Reinhard Lipowsky and published by Springer Science & Business Media. This book was released on 2013-03-08 with total page 307 pages. Available in PDF, EPUB and Kindle. Book excerpt: Membranes composed of amphiphilic molecules are highly flexible surfaces that determine the architecture of biological systems and provide a basic structural element for complex fluids such as microemulsions. Recently, a variety of new experimental methods such as X-ray scattering, neutron scattering, and atomic force microscopy have been used in order to study themolecular structure of these membranes. Their conformational behavior, on the other hand, is studied by optical and electron microscopy, which reveals that membranes in aqueous solution exhibit an amazing variety of different shapes. Several theoretical concepts are described suchas bending elasticity, curvature, and minimal surfaces in order to understand this polymorphism. These concepts are also useful to describe the behavior of membranes in complex fluids where they can build up hexagonal, lamellar, triply-periodic, cubic, and sponge phases. The contributions to this volume provide an up-to-date overview and describe thestate-of-the-art of this rapidly evolving field of research.
Download or read book The Biophysics of Cell Membranes written by Richard M. Epand and published by Springer. This book was released on 2017-09-25 with total page 224 pages. Available in PDF, EPUB and Kindle. Book excerpt: This volume focuses on the modulation of biological membranes by specific biophysical properties. The readers are introduced to emerging biophysical approaches that mimick specific states (like membrane lipid asymmetry, membrane curvature, lipid flip-flop, lipid phase separation) that are relevant to the functioning of biological membranes. The first chapter describes innovative methods to mimic the prevailing asymmetry in biological membranes by forming asymmetrical membranes made of monolayers with different compositions. One of the chapters illustrates how physical parameters, like curvature and elasticity, can affect and modulate the interactions between lipids and proteins. This volume also describes the sensitivity of certain ion channels to mechanical forces and it presents an analysis of how cell shape is determined by both the cytoskeleton and the lipid domains in the membrane. The last chapter provides evidence that liposomes can be used as a minimal cellular model to reconstitute processes related to the origin of life. Each topic covered in this volume is presented by leading experts in the field who are able to present clear, authoritative and up-to-date reviews. The novelty of the methods proposed and their potential for a deeper molecular description of membrane functioning are particularly relevant experts in the areas of biochemistry, biophysics and cell biology, while also presenting clear and thorough introductions, making the material suitable for students in these fields as well.
Download or read book Oral Delivery of Insulin written by T.A. Sonia and published by Elsevier. This book was released on 2014-12-11 with total page 361 pages. Available in PDF, EPUB and Kindle. Book excerpt: Diabetes Mellitus, a syndrome of disordered metabolism, characterised by abnormal elevation in blood glucose level, has become a life-threatening condition for many people. Current means of therapy for Diabetes Mellitus do not mimic the normal physiological pattern of insulin release. Oral delivery is the preferred route of administration due to its non-invasive nature. Oral delivery of insulin presents an overview of Diabetes Mellitus, and discusses the strategies and techniques adopted for oral delivery of insulin. This title begins with an introductory chapter on symptoms, complications and therapy for Diabetes Mellitus. Subsequent chapters cover the various routes for administering insulin; the challenges and strategies of oral delivery; experimental techniques in the development of an oral insulin carrier; lipids; inorganic nanoparticles and polymers in oral insulin delivery; and a summary and presentation of future perspectives on oral delivery of insulin. Presents an overview of Diabetes Mellitus Includes a discussion of various strategies and techniques adopted for oral delivery of insulin Presents an update of research in the field
Download or read book Physics and Chemistry of Interfaces written by Hans-Jürgen Butt and published by John Wiley & Sons. This book was released on 2023-02-07 with total page 485 pages. Available in PDF, EPUB and Kindle. Book excerpt: Physics and Chemistry of Interfaces Comprehensive textbook on the interdisciplinary field of interface science, fully updated with new content on wetting, spectroscopy, and coatings Physics and Chemistry of Interfaces provides a comprehensive introduction to the field of surface and interface science, focusing on essential concepts rather than specific details, and on intuitive understanding rather than convoluted math. Numerous high-end applications from surface technology, biotechnology, and microelectronics are included to illustrate and help readers easily comprehend basic concepts. The new edition contains an increased number of problems with detailed, worked solutions, making it ideal as a self-study resource. In topic coverage, the highly qualified authors take a balanced approach, discussing advanced interface phenomena in detail while remaining comprehensible. Chapter summaries with the most important equations, facts, and phenomena are included to aid the reader in information retention. A few of the sample topics included in Physics and Chemistry of Interfaces are as follows: Liquid surfaces, covering microscopic picture of a liquid surface, surface tension, the equation of Young and Laplace, and curved liquid surfaces Thermodynamics of interfaces, covering surface excess, internal energy and Helmholtz energy, equilibrium conditions, and interfacial excess energies Charged interfaces and the electric double layer, covering planar surfaces, the Grahame equation, and limitations of the Poisson-Boltzmann theory Surface forces, covering Van der Waals forces between molecules, macroscopic calculations, the Derjaguin approximation, and disjoining pressure Physics and Chemistry of Interfaces is a complete reference on the subject, aimed at advanced students (and their instructors) in physics, material science, chemistry, and engineering. Researchers requiring background knowledge on surface and interface science will also benefit from the accessible yet in-depth coverage of the text.
Download or read book Physics of Amphiphilic Layers written by Jacques Meunier and published by Springer Science & Business Media. This book was released on 2012-12-06 with total page 408 pages. Available in PDF, EPUB and Kindle. Book excerpt: Amphiphilic layers play essential roles in the behaviour of a great variety of disperse systems such as micelles, microemulsions and vesicles. They can also exist as isolated mono- or bilayers, or constitute extended liquid crystalline structures. Although the properties of these different systems may at first sight seem unrelated, theoretical interpretations of them depend on several common concepts. This was the reason for bringing together scientists working in this area for the International Winter School on the Physics of Amphiphilic Layers, which was held at Les Houches, 10-18 February, 1987. The topics treated in the proceedings volume are mono- and bilayers, interactive forces between layers (with special emphasis on steric forces), ordered structures (in particular swollen lamellar phases and defects), vesicles, micelles (including polymer-like systems), microemulsions (especially random bicontinuous structures) and porous media. The importance of thermal fluctuations in the amphiphilic layers is stressed. Recent results are presented and literature references allow readers not familiar with the subject to find any background information they require.
