1,721,001 research outputs found
7 Walde P. ,Wick R. , Fresta M. , Autopoietic self-reproduction of fatty acid vesicles J. Am. Chem. Soc. 116 (1994) 11649
No full textApplication of a new, simple and economic colorimetric method for the determination of non-esterified fatty acids in vegetable oils
No full textThe amount of non-esterified fatty acids in eight different vegetable oil samples has been determined by two different methods: (a) with a standard titration procedure, and (b) with a new colorimetric method which utilizes phenol red solubilized in reverse micelles. The results obtained by the two methods are in good agreement, although the standard deviation in the case of the phenol red method is significantly higher compared with the conventional titration. The main advantage of the new colorimetric method is an economic one: only small amounts of oil samples (less than 0·1 ml) are required and a comparably small amount of organic solvent (less than 5 ml isooctane) is needed
Giant Vesicles as Micro-Sized Enzymatic Reactors: Perspectives and Recent Experimental Advancements
No full textSynthetic cells can be constructed by encapsulating an appropriate set of molecules inside lipid vesicles (liposomes). They can be used as primitive cell model or for biotechnological applications. At these aims, it is important to develop experimental methods for liposome formation, solute encapsulation, and solute exchange across the lipid membrane. Here we focus on (i) the encapsulation of a polymer-enzyme (peroxidase) conjugate inside giant vesicles (GVs) prepared from phospholipids, and its reaction with Amplex Red reagent; and (ii) on the formation of amphotericin B pores allowing the entrance of cobalt ions inside calcein-containing vesicles, with the aim of developing experimental methods for constructing cell-like systems capable of processing chemicals. The presented approach is also shortly discussed from the viewpoint of chemical computing
Differential effects of liposome-entrapped desferrioxamine on proliferation and erythroid differentiation of murine erythroleukemic Friend cells
No full textIt is known that iron chelators (such as desferrioxamine) are potent inhibitors of both cell proliferation and erythroid differentiation. We have shown with in vitro studies that in the case of tumor cells desferrioxamine is even more efficient in inhibiting cell proliferation when entrapped in liposomes consisting of egg yolk phosphatidylcholine. At the same time liposome-entrapped desferrioxamine retains only a slight effect on hexamethylenebisacetamide induction of erythroid differentiation and hemoglobin accumulation of murine erythroleukemic Friend cells. Based on these findings, we propose liposome-entrapped desferrioxamine as potential antineoplastic agent as well as a specific chemical for the study of both iron metabolism and distribution in normal and neoplastic cells. In addition, unlike free desferrioxamine, the liposome-entrapped drug could also be used in combination with inducers of differentiation. With respect to this issue, it is possible that liposome-entrapped desferrioxamine, might permit erythroid differentiation of both neoplastic cells as well as normal stem cells. © 1989
Emergent properties arising from the assembly of amphiphiles. Artificial vesicle membranes as reaction promoters and regulators
No full textEmergent properties arising from the assembly of amphiphiles. Artificial vesicle membranes as reaction promoters and regulators
No full textThis article deals with artificial vesicles and their membranes as reaction promoters and regulators. Among the various molecular assemblies which can form in an aqueous medium from amphiphilic molecules, vesicle systems are unique. Vesicles compartmentalize the aqueous solution in which they exist, independent on whether the vesicles are biological vesicles (existing in living systems) or whether they are artificial vesicles (formed in vitro from natural or synthetic amphiphiles). After the formation of artificial vesicles, their aqueous interior (the endovesicular volume) may become – or may be made – chemically different from the external medium (the exovesicular solution), depending on how the vesicles are prepared. The existence of differences between endo- and exovesicular composition is one of the features on the basis of which biological vesicles contribute to the complex functioning of living organisms. Furthermore, artificial vesicles can be formed from mixtures of amphiphiles in such a way that the vesicle membranes become molecularly, compositionally and organizationally highly complex, similarly to the lipidic matrix of biological membranes. All the various properties of artificial vesicles as membranous compartment systems emerge from molecular assembly as these properties are not present in the individual molecules the system is composed of. One particular emergent property of vesicle membranes is their possible functioning as promoters and regulators of chemical reactions caused by the localization of reaction components, and possibly catalysts, within or on the surface of the membranes. This specific feature is reviewed and highlighted with a few selected examples which range from the promotion of decarboxylation reactions, the selective binding of DNA or RNA to suitable vesicle membranes, and the reactivation of fragmented enzymes to the regulation of the enzymatic synthesis of polymers. Such type of emergent properties of vesicle membranes may have been important for the prebiological evolution of protocells, the hypothetical compartment systems preceding the first cells in those chemical and physico-chemical processes that led to the origin of life
pH-Sensitive Vesicles Containing a Lipidic -Amino Acid with Two Hydrophobic Chains
No full textThe lipidic -amino acid 2-(aminomethyl)-2-pentadecylheptadecanoic acid (1) was synthesized via the alkylation of the C()-atom of fully protected -alanine. Mixed large unilamellar vesicles with a diameter between 100 and 200 nm containing POPC (1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine) and 1 at a molar ratio of 9 : 1 were prepared and found to have a surface charge which is dependent on pH. At slightly acidic pH, the vesicles were positively charged, and at alkaline pH negatively charged. Dynamic light scattering, zeta potential, and cryo-transmission electron-microscopy measurements indicated that the mixed vesicles fused at pH 4-5 with negatively charged mixed vesicles composed of POPC and POPG (9.8 : 1, molar ratio), POPG being 1-palmitoyl-2-oleoyl-sn-glycero-3-[phospho-rac-(1-glycerol)]
Giant Vesicles: Preparations and Applications
No full text(Figure Presented) There is considerable interest in preparing cell-sized giant unilamellar vesicles from natural or nonnatural amphiphiles because a giant vesicle membrane resembles the self-closed lipid matrix of the plasma membrane of all biological cells. Currently, giant vesicles are applied to investigate certain aspects of biomembranes. Examples include lateral lipid heterogeneities, membrane budding and fission, activities of reconstituted membrane proteins, or membrane permeabilization caused by added chemical compounds. One of the challenging applications of giant vesicles include gene expressions inside the vesicles with the ultimate goal of constructing a dynamic artificial cell-like system that is endowed with all those essential features of living cells that distinguish them from the nonliving form of matter. Although this goal still seems to be far away and currently difficult to reach, it is expected that progress in this and other fields of giant vesicle research strongly depend on whether reliable methods for the reproducible preparation of giant vesicles are available. The key concepts of currently known methods for preparing giant unilamellar vesicles are summarized, and advantages and disadvantages of the main methods are compared and critically discussed. © 2010 Wiley-VCH Verlag GmbH & Co. KGaA
Liposome mediated delivery of retinoids and aromatic polyamidines: Effects on growth of tumor cell lines
No full textThis paper describes the increase of antiproliferative activity toward tumor cell lines of liposome-delivered retinoids and aromatic polyamidine
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