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Surfactant Shell (surfactant + shell)
Selected AbstractsNondestructive characterization of ferrofluids by wide-angle synchrotron light diffraction: crystalline structure and size distribution of colloidal nanoparticlesJOURNAL OF APPLIED CRYSTALLOGRAPHY, Issue 5 2008Alexei Vorobiev The combination of magnetic and nonmagnetic interactions between the colloidal particles in ferrofluids results in various local inter-particle correlations that, in turn, change the macroscopic properties of the whole system. Therefore, characterization of the particle ensemble is a crucial point, allowing optimization of a ferrofluid for a particular application. Here it is shown how the crystal structure of the particles can be easily obtained in a fast synchrotron light diffraction experiment without any special treatment of the ferrofluid sample. Moreover, from the same diffraction patterns, such important parameters as particle mean size and dispersion are retrieved; these are compared with the corresponding parameters obtained from electron microscopy data. A particular problem of magnetite,maghemite transformation in nanoparticles stabilized by the surfactant shell is pointed out. [source] Small-angle neutron and X-ray scattering of dispersions of oleic-acid-coated magnetic iron particlesJOURNAL OF APPLIED CRYSTALLOGRAPHY, Issue 6 2004Karen Butter This paper describes the characterization of dispersions of oleic-acid-coated magnetic iron particles by small-angle neutron and X-ray scattering (SANS and SAXS). Both oxidized and non-oxidized dilute samples were studied by SANS at different contrasts. The non-oxidized samples are found to consist of non-interacting superparamagnetic single dipolar particles, with a lognormal distribution of iron cores, surrounded by a surfactant shell, which is partially penetrated by solvent. This model is supported by SAXS measurements on the same dispersion. Small iron particles are expected to oxidize upon exposure to air. SANS was used to study the effect of this oxidation, both on single particles, as well as on interparticle interactions. It is found that on exposure to air, a non-magnetic oxide layer is formed around the iron cores, which causes an increase of particle size. In addition, particles are found to aggregate upon oxidation, presumably because the surfactant density on the particle surfaces is decreased. [source] Iron oxide-based magnetic nanostructures bearing cytotoxic organosilicon molecules for drug delivery and therapyAPPLIED ORGANOMETALLIC CHEMISTRY, Issue 3 2010Alla Zablotskaya Abstract The results of our own investigation on synthesis, physico-chemical and biological study of iron oxide based magnetic nanoparticles bearing cytotoxic organosilicon molecules of choline and colamine analogues, as potential agents for antitumor therapy, are summarized. These molecules contain hydrophilic head and long lipophilic tails, which are able to deepen inside the first surfactant shell (oleic acid), forming bilayer membrane like structures. Such compositions have a great privilege possessing magnetic properties, which in some cases could be essential moment in targeted drug delivery. The methodological approach has been developed and applied to the preparation of water soluble single or mixed coated biologically active nanoparticles of different types. Copyright © 2010 John Wiley & Sons, Ltd. [source] Microbubble-enriched lavage fluid for treatment of experimental peritonitisBRITISH JOURNAL OF SURGERY (NOW INCLUDES EUROPEAN JOURNAL OF SURGERY), Issue 4 2008P. K. Sharma Background: Relaparotomies and closed postoperative peritoneal lavage (CPPL) are performed to treat persistent peritonitis. This experimental animal study compared open abdominal lavage with CPPL, and evaluated the potential of microbubble-enriched lavage fluids to improve the efficiency of CPPL and reduce clinical morbidity, mortality and cost. Methods: Fluorescent polystyrene spheres were injected intraperitoneally into 22 male Wistar rats to simulate localized peritonitis. After 18 h the rats received open abdominal lavage and CPPL, with and without microbubbles. Microbubbles were obtained by adding ultrasound contrast agents to continuous ambulatory peritoneal dialysis fluid. Results: Open abdominal lavage was 3·5 times more effective in particle removal than CPPL, owing to better fluid dynamics. The introduction of air,liquid interfaces in the form of microbubbles made CPPL up to 2·4 times more effective than lavage without bubbles. Best detachment results were obtained when microbubbles with a flexible surfactant shell and longer blood elimination half-life were used. Conclusion: Open abdominal and CPPL lavage techniques are not efficient beyond a certain duration and volume as they do not cause bacterial detachment from the peritoneal membrane. Using surface tension forces from microbubbles significantly enhanced polystyrene particle detachment. These findings may have great consequences for the treatment of patients with peritonitis. Copyright © 2007 British Journal of Surgery Society Ltd. Published by John Wiley & Sons, Ltd. [source] | ||||||||||