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Genosomes (DNA−Lipid Complexes)
Published in Danilo D. Lasic, LIPOSOMES in GENE DELIVERY, 2019
Stability of colloidal systems can be explained by the DLVO theory which states that the balance between ubiquitous van der Waals attraction and electrostatic repulsion determines the stability of the system. Quantitative agreement with the model was observed although preliminary ζ potential measurements at these high surface charges did not obey the Poisson–Boltzmann equation (Lasic, unpublished). Lower than expected surface charges may be due to counterion association (Israelachvili, private communication). It is well known that degree of ionization a can be close to 1 for monomeric surfactants while upon micellization it can drop below α < 0.3.
Toxicology Studies of Semiconductor Nanomaterials: Environmental Applications
Published in Suresh C. Pillai, Yvonne Lang, Toxicity of Nanomaterials, 2019
T. P. Nisha, Meera Sathyan, M. K. Kavitha, Honey John
After penetrating into the cells, nanoparticles can interact with biomolecules like proteins, nucleic acids, and lipids and can affect their biological activity. Their interaction with bacterial cells depends on interfacial force between them. It is observed that nanoparticles with fewer interfacial energy barriers can have strong interaction with cells and induce cytotoxicity. A quantitative correlation between interfacial interaction between nanoparticles and cell membrane can be established by the Derjaguin-Landau-Verwey-Overbeek (DLVO) theory (Li et al., 2012a) and it has been observed that acute toxicity of seven different metal oxide nanoparticles towards paramecia are in the order of Al2O3 < TiO2 < CeO2 < ZnO < SiO2 < CuO <Fe2O3 (Figure 4.4).
Polymer Adsorption: Fundamentals
Published in E. Desmond Goddard, James V. Gruber, Principles of Polymer Science and Technology in Cosmetics and Personal Care, 1999
E. Desmond Goddard, James V. Gruber
It can be seen then that not only does decrease exponentially with distance, but it is also decreased by a rise in the solution electrolyte concentration (increase in \kappa). For a solution of a 1:1 electrolyte the thickness of the double , is approximately , but if the electrolyte concentration increases to , then falls to . DLVO THEORY
Enhanced intestinal absorption of asenapine maleate by fabricating solid lipid nanoparticles using TPGS: elucidation of transport mechanism, permeability across Caco-2 cell line and in vivo pharmacokinetic studies
Published in Artificial Cells, Nanomedicine, and Biotechnology, 2019
Mitali Patel, Veenu Mundada, Krutika Sawant
However, particle size was increased whereas zeta potential and drug content were decreased when they were stored at RT. Drug content may have decreased at 30 °C because of drug expulsion from the lipid matrices at higher temperature [39]. According to the DLVO theory, a system can be regarded as stable if the electrostatic repulsion dominates the attractive van der Waals forces. The particles have to overcome an energy barrier of electrostatic repulsion to approach closely and form agglomerates. If their velocity or kinetic energy is high enough they will collide. At high temperature (30 °C), the kinetic energy of a system increases which dominates the attractive forces over repulsive forces, reducing the zeta potential which may have led to particle aggregation [40]. Hence, recommended storage condition for better stability of AM loaded SLN is under refrigeration.
Lycopene solid lipid microparticles with enhanced effect on gingival crevicular fluid protein carbonyl as a biomarker of oxidative stress in patients with chronic periodontitis
Published in Journal of Liposome Research, 2019
Maie S. Tawfik, Khaled A. Abdel-Ghaffar, Ahmed Y. Gamal, Fatma H. El-Demerdash, Heba A. Gad
Increasing the lipid ratio from 20 to 30 in the preparation of SLMs resulted in a significant increase (p < 0.05) in particle size. However, increase lipid ratio from 30 to 40 and 60 resulted in a non-significant (p > 0.05) increase in PS. The highest investigated ratio of 100 resulted in marked increase in both PS and SI (Table 1). The obtained results may be explained by the high degree of interaction of monoglycerides with water. According to previous work, lipids may be classified by their interaction with water. Monoglycerides belong to the group of polar lipids, in the presence of water; these lipids swell and reorganize into the aqueous–organic interface, increasing their surfactant properties (Jensen et al. 2010). LP-SLMs show zeta potential values from −35.89 ± 2.11 to −50.12 ± 4.15 mV, which indicates good physical stability according to the theory of Derjaguin–Landau–Verwey– Overbeek (DLVO). The DLVO theory stated that electrostatic repulsive forces between particles which are donated by high zeta potential values (>|30| mV), result in less particle aggregation (Souto et al. 2004, Gabal et al. 2014).
CFD-based prediction of initial microalgal adhesion to solid surfaces using force balances
Published in Biofouling, 2021
S. Kichouh-Aiadi, A. Sánchez-Mirón, J. J. Gallardo-Rodríguez, Y. Soriano‐Jerez, M. C. Cerón-García, F. García-Camacho, E. Molina-Grima
Some adhesion models are based on thermodynamics; these try to explain adhesion using the concept of surface free energy, without taking electrostatic interactions into account (Bos et al. 1999). Other models are based on the wide range of interaction forces exerted on cells; these can be classified as: interactions between particles, interactions between particles and surfaces, and interactions between particles and the fluid (fluid-dynamic forces). In this last group, fluid-dynamic forces generally include drag force, lift force, and buoyancy force. Usually, the magnitude of the fluid-dynamic forces needed to prevent adhesion is smaller than the values needed to detach the cells (Boks et al. 2008). Among the models based on the balance of forces, the most used has been the DLVO theory (from the initials of its authors: Derjaguin, Landau, Verwey, and Overbeek), which dates from the 1940s, and its extension, the XDLVO model, introduced by van Oss (1993). These explain cell adhesion based on a balance of non-covalent short-range attractive and repulsive forces: Lifshitz-van der Waals, electrostatic, Lewis acid-base, and the Brownian force of motion (Bos et al. 1999). The Basset force, the virtual mass force, the force of Brownian motion and the magnus force are negligible at low fluid velocities, when the particles are small and spherical in shape (Kallio and Reeks 1989; McLaughlin 1989; Zhang and Chen 2009; Barker 2010). Ozkan and Berberoglu (2013) demonstrated that the XDLVO model accurately explained the forces responsible for microalgal adhesion to solid surfaces. The interaction forces, which only exist very close to the wall, are critical, as they determine the onset of biofouling (van Oss 1993; Bos et al. 1999; Zeriouh et al. 2017). Furthermore, the forces change over time because the surface properties also do this, being able to increase by several orders of magnitude in just one hour (Dąbroś and Van De Ven 1982).