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Surfactants in Cosmetic Products
Published in Heather A.E. Benson, Michael S. Roberts, Vânia Rodrigues Leite-Silva, Kenneth A. Walters, Cosmetic Formulation, 2019
Ricardo Pedro, Kenneth A. Walters
As previously mentioned, surfactants accumulate at the air–water interface where their non-polar tails protrude into the air or lipid phase, avoiding unfavourable interactions with water, while the polar end of the molecule interacts favourably with water. The surfactants replace some of the surface molecules of water, decreasing the net surface tension. The most important methods for measuring interfacial properties in equilibrium conditions include the du Noüy ring method, Wilhelmy plate method, capillary rise method and spinning drop method (Surfactant Science Series, 1999).
Pulmonary Phosphatidate Phosphohydrolase and Its Relation to the Surfactant System of the Lung *
Published in David N. Brindley, John R. Sabine, Phosphatidate Phosphohydrolase, 2017
As indicated in Section II, pulmonary surfactant was rediscovered by Clements through the use of a modified Langmuir-trough-Wilhelmy balance (Figure 2). This apparatus requires that the sample either be spread at the air-liquid interface or be adsorbed to the surface over a period of time. The resulting data give information concerning the compression or the respreading ability of the preparations. More recently, techniques have been introduced which examine the adsorption and spreading of surfactant at the air-liquid interface.187–189 King and Clements190 have introduced an adsorption assay which utilized a Wilhelmy platinum plate suspended in a large volume of saline medium in a Teflon beaker. A small sample of surfactant is injected into the subphase and the assay is initiated by activating a magnetic stir bar. The Wilhelmy plate monitors the surface tension with respect to time through a strain gauge. The end point achieved with this assay is approximately 27 dyne/cm. This corresponds to the equilibrium surface tension of a monolayer saturated with DPPC. In order to obtain lower surface tensions, it is necessary to compress the surface area either by a barrier as with the modified Langmuir trough or by decreasing the volume of a bubble. Samples of natural surfactant reduce the surface tension to approximately 27 dyne/cm within a few minutes. Pure lipids or the lipids extracted from surfactant produce only a slow moderate decline in surface tension with this apparatus.190–193
Investigation of propellant-free aqueous foams as pharmaceutical carrier systems
Published in Pharmaceutical Development and Technology, 2021
Dóra Farkas, Nikolett Kállai-Szabó, Ágnes Sárádi-Kesztyűs, Miléna Lengyel, Sabrina Magramane, Éva Kiss, István Antal
The surface tension of the aqueous solutions was determined using a computer-controlled, programmable dynamic tensiometer (KSV Sigma 70, KSV Instrument Ltd., Helsinki, Finland) with a Wilhelmy plate (micro-roughened platinum, width = 19.6 mm, thickness = 0.1 mm). The tensiometer was calibrated for ultrapure water at room temperature (70.71 mN/m). The surface tension measurements are the average of three parallels, and the accuracy was estimated to ±0.3 mN/m.
Jet milling industrialization of sticky active pharmaceutical ingredient using quality-by-design approach
Published in Pharmaceutical Development and Technology, 2019
Mostafa Nakach, Jean-René Authelin, Carlo Corsini, Giovanni Gianola
The surface tension (γ) of cleaning agent was measured using KRÜSS K12® tensiometer (KRÜSS GmbH, Germany). The Wilhelmy plate method (S. C. Biswas et al. 2001) was applied under quasi-equilibrium conditions. The force required to detach the plate from the interface was accurately determined. The measurements were carried out at room temperature and repeated three times.
A novel osmoprotective liposomal formulation from synthetic phospholipids to reduce in vitro hyperosmolar stress in dry eye treatments
Published in Journal of Liposome Research, 2023
Miriam Ana González Cela Casamayor, José Javier López Cano, Vanessa Andrés Guerrero, Rocío Herrero Vanrell, José Manuel Benítez del Castillo, Irene Teresa Molina Martínez
The formulations’ surface tension values were acquired using a digital tensiometer K-11 (Kruss GmbH, Hamburg, Germany) based on the Wilhelmy plate method. Firstly, the equipment was calibrated using distilled water (68–72 mN/m) at 32 °C (ocular surface temperature).