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The Hydrophilic-Hydrophobic Correlations in Water Systems
Published in Fausto Martelli, Properties of Water from Numerical and Experimental Perspectives, 2022
Francesco Mallamace, Carmelo Corsaro, Paola Lanzafame, Georgia Papanikolaou, Domenico Mallamace
Hydrophobic Interactions: HEs with few directional constraints are the main driving forces in surfactant systems. A Water molecule cannot interact favorably with an apolar one and when amphipathic molecules are put into water, their hydrophobic parts try to aggregate, minimizing their surface are a in contact with the solvent, leaving only the hydrophilic parts exposed to water. The, hydrophobic interactions are thus stabilized by increasing entropy rather than enthalpy (Ben-Amotz 2015). All of this leads to the formation of micellar structures. In a salt-triggered self-assembly process, the role of HE driving forces, due to charge-screening effects, are significantly enhanced. In the case of bio-systems, is must be said that HE forces are important for the rational design of peptide amphiphiles. In particular, both the HE and π−π interaction play important roles in the organization modes of peptide aromatic residues: in the first case these are disordered, while in the second one, they are well organized and ordered.
Cell Biology for Bioprocessing
Published in Wei-Shou Hu, Cell Culture Bioprocess Engineering, 2020
The lipids that make up the lipid bilayer are amphipathic phospholipids. Each phospholipid molecule consists of a glycerol backbone linking a hydrophilic head group that includes a charged phosphate group and a hydrophobic tail group consisting of two fatty acids (Figure 2.3). The fatty acids at the hydrophobic tail provide the hydrophobic interactions necessary to form the ordered structure of a membrane at a mild temperature. When suspended in an aqueous solution, amphipathic molecules can form micelles. In such micelles, the hydrophilic heads face outward and the hydrophobic tails project inward. The organization of a micelle makes it easy to enclose hydrophobic molecules inside while not having an aqueous environment both inside and outside. In contrast, a sphere formed by a lipid bilayer membrane has the hydrophobic tails projecting toward the middle of the bilayer and the hydrophilic heads on the external as well as the internal surfaces. It can readily have an aqueous environment both inside and outside (Figure 2.4).
Encapsulation of Polyphenols Into Micro- and Nanoparticles for Improved Health Effects
Published in Ali Pourhashemi, Sankar Chandra Deka, A. K. Haghi, Research Methods and Applications in Chemical and Biological Engineering, 2019
Anurag Maurya, Monoj Kumar Das, Anand Ramteke, Sankar Chandra Deka, Neelu Singh, Paulraj Rajamani
Emulsions are dispersion of one liquid into another which are normally immiscible, for example, oil and water. Oil is dispersed in aqueous phase and is called oil-in-water system, whereas water droplets dispersed in oil is termed as water-in-oil system. An amphipathic molecule, called emulsifier, is essential to stabilize emulsion. It prevents agglomeration of dispersed phase. Nanoemulsions are colloidal solution of two immiscible liquids having colloidal particles less than 100 nm. High energy homogenization process and large amount of emulsifier is applied for nanoemulsion preparation. High-shear mixer, high-pressure homogenizer, microfluidizer, membrane microchannel homogenizer are the techniques applied for large scale emulsification. A laboratory homogenizer and sonication can be used for small scale emulsification. Emulsifier provides stability in liquid state, while for long term storage, emulsion can be spray dried to powder.14,30
Concentration-dependent physicochemical behaviors and micellar interactions in polyalkoxylated fatty alcohol-based binary surfactant systems
Published in Journal of Dispersion Science and Technology, 2021
Chaw Jiang Lim, Chan Kiang Lim, Gwendoline Cheng Lian Ee
In recent years, public growing awareness on the depleting fossil resources and greenhouse gas emission has triggered the pressing need and rising use of renewable-based surfactants over the petrochemical-based surfactants.[1] Surfactants have been extensively harnessed for multifarious applications in pharmaceuticals, cosmetics, agrochemicals, paints, plastics, fibers and dyestuffs.[2] Surfactants have dual distinct parts coexisting of hydrophilic headgroups and hydrophobic chains. The amphipathic molecules could orient at the interface of oil and water to confer an emulsion with high stability. Surfactants are categorized based on the types of headgroup which are nonionic, anionic, cationic and zwitterionic. Among them, nonionic and anionic surfactants are the most made from renewable feedstocks which are promoting high biodegradability and environmental compatibility.[3,4] Besides that, zwitterionic surfactants are gentle to human skin, less ecotoxicity and good biodegradability.[5,6]
Biosurfactant produced by oil-degrading Pseudomonas putida AM-b1 strain with potential for microbial enhanced oil recovery
Published in Bioremediation Journal, 2019
Milena Maia, Artur Capão, Luciano Procópio
Surfactants are active compounds described as molecules with amphipathic characteristics, due to the presence of hydrophobic or nonpolar and hydrophilic or polar groups in the same structure, and thus tend to accumulate between organic and aqueous phases, minimizing surface and interfacial tensions (Fiechter 1992; Singh, Patil, and Rale 2019). Commonly, the hydrophilic grouping is ionic, nonionic or amphoteric, and the hydrophobic group is a hydrocarbon chain. The role of the biosurfactants can be observed in the formation of a molecular film between the oil and water phases and in the formation of microemulsions, where it is possible to solubilize hydrocarbons in water (Deasi and Banat 1997).
Effects of stretching on molecular transfer from cell membrane by forming pores
Published in Soft Materials, 2019
Amin Hadi, Abbas Rastgoo, Azam Bolhassani, Nooshin Haghighipour
The amphipathic nature of phospholipids is the key factor in their interaction and it plays a very important role in the membrane structures’ formation. The hydrophobic nature of the fatty acid chains leads to diverse organization of phospholipids. In the normal condition, phospholipid compounds present in the aqueous medium spontaneously form phospholipid bilayer. Compression near the nonpolar tail becomes possible by the Van der Waals interaction among hydrocarbon chains. The ionic and hydrogen interaction of the polar heads in regard to each other and also the water stabilizes the membrane structures (47).