Polymer Adsorption: Fundamentals
E. Desmond Goddard, James V. Gruber in Principles of Polymer Science and Technology in Cosmetics and Personal Care, 1999
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
Genosomes (DNA−Lipid Complexes)
Danilo D. Lasic in 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preliminary ζ potential measurements at these high surface charges did not obey the Poisson–Boltzmann equation (Lasic, unpublished).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.
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.
Systematic development and characterization of curcumin-loaded nanogel for topical application
Published in Drug Development and Industrial Pharmacy, 2020
Payal Kesharwani, Ankit Jain, Anand Kumar Srivastava, Mahendra Kumar Keshari
Zeta potential of batch F10 was obtained to be −21.45 mV stipulating negative charge on NLC. Literature reveals that a high value of zeta potential signifies electrostatic repulsion between two particles [65]. DLVO theory states that electrical double layer repulsion will stabilize NLC and aggregation will not take place due to high negatively charged particles [66]. Highly charged nanoparticles are better able to remain stable as a colloidal suspension, since columbic repulsion force, arising from their surface charge can overcome Vander walls attractive force between them and prevent aggregation upon aging [67].
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).
Related Knowledge Centers
- Colloid
- Counterion
- Debye Length
- Dispersion
- Particle Aggregation
- Double Layer
- Bjerrum Length
- Activation Energy
- Debye–Hückel Equation
- Hamaker Constant