Comparison of DLPC and DPPC in Controlling the Dynamic Adsorption and Surface Tension of Their Aqueous Dispersions

Abstract

The adsorption of dilauroylphosphatidylcholine (DLPC) at the air/ water interface was investigated with tensiometry, infrared reflection-absorption spectroscopy (IRRAS), and ellipsometry. The tension dynamics at 25 °C at constant and pulsating area depends strongly on the concentration (10-1000 ppm) and sizes of dispersed DLPC particles, which are liposomes or vesicles. Dynamic surface tensions as low as 1-5 mN/m are observed for DLPC. For dipalmitoylphosphatidylcholine (DPPC), such tensions are also observed, but only for certain special preparation procedures. Direct probing of the surface by IRRAS and ellipsometry indicates that DLPC adsorbs by a molecular adsorption mechanism, controlled largely by the rate of dissolution of the dispersed particles. The surface layer is a monolayer with no particles attached to it, unlike DPPC in which the surface monolayer forms by particles which reach the interface and remained attached to it (Wen, X.; Franses, E. I. Langmuir 2001, 17, 3194). Spectroturbidimetry and dialysis experiments, used to determine the DLPC solubility in water as 4 ( 1 ppm and the DPPC solubility as essentially zero, support the above mechanisms. For DLPC, a simple diffusion/adsorption model with molecular diffusion and variable effective diffusion length can account for the dynamic surface tension data.

Surface tension and adsorption behavior of mixtures of diacyl glycerol arginine-based surfactants with DPPC and DMPC phospholipids

“…The lowest minimum surface tensions, about 2 mN/m, were observed at X = 0.5 for 1212RAc/DMPC. When the measured minimum surface tension was below 5 mN/m, substantial gravity-induced bubble deformation was observed, as reported previously [31,43,44]. The dynamic surface tension maxima, max (not shown) were quite high, ranging from 72 to 70 mN/m for surfactants and from 72 to 60 mN/m for the phospholipids.…”

“…Surfactant/phospholipid mixtures, at surfactant mole fractions X of 0.3, 0.5, and 0.7, and pure surfactant or phospholipid dispersions, were prepared at a total concentration C T of 500 M. They all showed a substantial turbidity, indicating they were twophase dispersions. The solubility of each surfactant is well below 50 M; that of DPPC and DMPC is well below 1 nM, or essentially "zero" [31]. The dispersions were shaken vigorously by hand at room temperature for 5 min, and then sonicated for 15 min in a sonicator bath (Branson 1200 Ultrasonic cleaner, Branson Cleaning Equipment Co., Shelton, CT).…”

“…Spectra were collected by using 1024 scans at an 8 cm −1 resolution with the Happ-Genzel apodization and one level of zero filling. Further details can be found elsewhere [31,39,40]. An incident angle of 40 • relative to the surface normal was used.…”

Restoration of the interfacial properties of lung surfactant with a newly designed hydrocarbon/fluorocarbon lipid

“…Though this does not conclusively prove that IPL removed all fibrinogen molecules from the interface, it is clear that the monolayer behaved in a manner similar to that observed when significant amounts of fibrinogen were not present at the interface. Previous studies performed with DLPC or DPPC vesicles did not show this promising result of the prevention of protein adsorption in the presence fibrinogen pre-adsorbed to the monolayer [51,57,21,58].…”

Synthetic and Physicochemical Aspects of Advanced Stimuli‐Responsive Polymers

“…However, the use of biologically active phospholipids (PLs) as a dispersing agent provides synthetic conditions under which p-methyl methacrylate/n-butyl acrylate/heptadecafluorodecyl methacrylate (p-MMA/nBA/FMA) copolymer colloidal dispersions containing up to 15% w/w of heptadecafluorodecyl methacrylate (FMA) were copolymerized. These particles exhibit nonspherical particle morphologies and the choice of 1,2-dilauroyl-sn-glycero-3-phosphocholine (DLPC) was dictated by the fact that combining this PL with SDS/FSP surfactants results in the reduction of the overall surface tension of the aqueous phase from 72 to about 1-5 mN m −1 [146]. These conditions appear to be essential during polymerization of F-containing colloidal particles because lower surface tension not only facilitates efficient monomer transport to the polymerization loci but also provides stability of colloidal particles after synthesis.…”