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The Cell Membrane in the Steady State
Published in Nassir H. Sabah, Neuromuscular Fundamentals, 2020
Suppose that the inner side of the membrane has a surface charge. This attracts an opposite charge in the adjacent solution, resulting in an electrical double layer that causes a jump in the voltage at the inner membrane boundary. Assuming a constant electric field in the membrane, the voltage profile can be represented as in Figure 2.13. Show that Equation 2.28 is modified to:
Male Methods
Published in Sujoy K. Guba, Bioengineering in Reproductive Medicine, 2020
An electrical charge effect is introduced to improve the differentiation between the species. Cells in the presence of electrolytes form a diffuse electric double layer and an intermediate rigid layer attached to the cell. Attraction of anions and cations to the cells surface leads to the formation of an ionic cloud which decreases in density with increasing distance from the cell surface. The Zeta potential (ξ) is the difference between the charge of the rigid layer and the suspending liquid and is given by
Tuning the Properties of Silver Monolayers for Biological Applications
Published in Huiliang Cao, Silver Nanoparticles for Antibacterial Devices, 2017
Based on the experimental results and using the abovementioned theoretical approach, the equilibrium adsorption constant and the energy minimum depth (binding energy of nanoparticles) were determined for various physicochemical conditions (Oćwieja and Adamczyk 2013; Oćwieja et al. 2015a). In contrast to predictions of the mean-field DLVO theory, the energy minima were little dependent on particle size, ionic strength and pH. Thus, for the typical desorption conditions of I = 10−2 M, pH 6.2–5.8, energy varied between −16.9 and −19.1 kT for the particle size of 15 and 54 nm, respectively (Oćwieja and Adamczyk 2013; Oćwieja et al. 2015a). The decrease in energy minimum depth with the temperature was also observed, which contradicts the mean-field theory. These experimental evidences indicated that the role of van der Waals interactions in the silver nanoparticle release processes from polyelectrolyte-covered mica was negligible. The kinetics of these processes was governed by discrete electrostatic interactions among ion pairs and cannot be properly described by mean-field theories of the electrical double layer.
Loading, release profile and accelerated stability assessment of monoterpenes-loaded solid lipid nanoparticles (SLN)
Published in Pharmaceutical Development and Technology, 2020
Aleksandra Zielińska, Nuno R. Ferreira, Agnieszka Feliczak-Guzik, Izabela Nowak, Eliana B. Souto
With respect to the zeta potential (ZP), this parameter translates the electrokinetic potential of colloidal dispersions, i.e. the electrical potential that exists at the slipping plane (the boundary of the electrical double layer of the particle). ZP can also be determined as the potential difference between the dispersion medium and the stationary layer of fluid attached to the dispersed particle. The value of the zeta potential indicates the degree of electrostatic repulsion between adjacent, similarly charged particles in a dispersion (Zielińska and Nowak 2016). Zeta potential was approximately |±0 mV| in all formulations, since the surfactant used has a non-ionic character forming a spherically stabilizing adsorbed polymer layer in the SLN surface (Souto, Baldim, et al. 2020).
Design and in vitro release study of siRNA loaded Layer by Layer nanoparticles with sustained gene silencing effect
Published in Expert Opinion on Drug Delivery, 2018
Yang Fei Tan, Ying Shi Lee, Li-Fong Seet, Kee Woei Ng, Tina T. Wong, Subbu Venkatraman
The electrophoretic mobility of the nanoparticles after the coating of each layer was measured in 0.2 µm filtered 0.1 M NaCl at room temperature using a Malvern Zetasizer 2000 (Malvern Instruments, UK). The zeta potential (ζ-potential) was calculated from the electrophoretic mobility (µ) using the Smoluchowski function ζ = µη/ε where η and ε were the viscosity and permittivity of the solvent, respectively. Since the nanoparticles synthesized were charged, the surrounding ions near the nanoparticles in the solution will be distributed into an electrical double layer. The zeta potential of the nanoparticles was the potential at the slipping plane. The zeta size of the nanoparticles was measured based on dynamic light scattering theory using the same equipment. The zeta size measured was the hydrodynamic size of the nanoparticles. A total of three readings were measured for each sample, and the experiment was conducted at least three times.
Surface properties, adhesion and biofilm formation on different surfaces by Scedosporium spp. and Lomentospora prolificans
Published in Biofouling, 2018
Thaís P. Mello, Simone S. C. Oliveira, Susana Frasés, Marta H. Branquinha, André L. S. Santos
The cell surface charge also mediates the initial adhesion process and this can be indirectly determined by measurement of the zeta potential, which is the parameter that determines the electrophoretic mobility of a charged particle in a liquid medium and represents the electric double layer around the cell (Miyake et al. 1990). The cell surface of both yeasts and conidia is usually negatively charged, as has been previously described for C. albicans, non-albicans Candida species, Cryptococcus neoformans, A. fumigatus, and Aspergillus niger (Miyake et al. 1990; Fráses et al. 2008; Pihet et al. 2009; Silva et al. 2010; Wargenau et al. 2011). In the present study, all the conidia exhibited a high electronegative zeta potential: L. prolificans (–60.36 ± 4.31 mV), S. minutisporum (–60.17 ± 5.43 mV), S. aurantiacum (–54.01 ± 9.35 mV), and S. apiospermum (–41.98 ± 9.45 mV) (Figure 1B). A negative correlation (r = –0.9876, p = 0.0124) was observed between the cell surface charge and CSH in the fungi studied herein (Figure 1C). The zeta potential values found here were similar to the high zeta potential measured in S. boydii conidial cells, which ranged from −39.00 mV to −49.30 mV depending on the conidial maturation phase (Ghamrawi et al. 2014).