Liposomes membrane fluidity

Arora A, Byrem TM, Nair MG, Strasburg GM. 2000. Modulation of liposomal membrane fluidity by flavonoids and isoflavonoids. Arch Biochem Biophys 373 102-109. 

In these studies of tobramycin liposomes, the authors attributed differences in tobramycin retention to differences in liposome membrane fluidity or charge... 

Kawano, K., Onose, E., Hattori, Y. et al. 2009. Higher liposomal membrane fluidity enhances the in vitro antitumor activity of folate-targeted liposomal mitoxantrone. Mol Pharm. 6 98-104. 

The binding of carotenoids within the lipid membranes has two important aspects the incorporation rate into the lipid phase and the carotenoid-lipid miscibility or rather pigment solubility in the lipid matrix. The actual incorporation rates of carotenoids into model lipid membranes depend on several factors, such as, the kind of lipid used to form the membranes, the identity of the carotenoid to be incorporated, initial carotenoid concentration, temperature of the experiment, and to a lesser extent, the technique applied to form model lipid membranes (planar lipid bilayers, liposomes obtained by vortexing, sonication, or extrusion, etc.). For example, the presence of 5 mol% of carotenoid with respect to DPPC, during the formation of multilamellar liposomes, resulted in incorporation of only 72% of the pigment, in the case of zeaxanthin, and 52% in the case of (1-carotene (Socaciu et al., 2000). A decrease in the fluidity of the liposome membranes, by addition of other... 

Cholesterol s presence in liposome membranes has the effect of decreasing or even abolishing (at high cholesterol concentrations) the phase transition from the gel state to the fluid or liquid crystal state that occurs with increasing temperature. It also can modulate the permeability and fluidity of the associated membrane—increasing both parameters at temperatures below the phase transition point and decreasing both above the phase transition temperature. Most liposomal recipes include cholesterol as an integral component in membrane construction. 

Wiseman H, Quinn P, Halliwell B (1993) Tamoxifen and related compounds decrease membrane fluidity in liposomes mechanism for the antioxidant action of tamoxifen and relevance to its anticancer and cardioprotective actions FEBS Lett 330( 1) 53—56... 

X-Y Liu, Q Yang, N Kamo, J Miyake. Effect of liposome type and membrane fluidity on drug-membrane partitioning analyzed by immobilized liposome chromatography. J Chromatogr A 913 123-131, 2001. 

The influence of physicochemical properties of liposomes, such as charge density, membrane fluidity, and epitope density, on the immune response elicited by antigens has been extensively studied [37]. In addition to antigens, other immune stimulators that are amphoteric muramyl peptides or lipid-soluble compounds, such as monophosphoryl lipid A or muramyl tripeptidyl-phosphatidylethanolamine, can also be incorporated into liposomes to increase their adjuvant effect in eliciting immune responses [34]. 

Other functional liposomes are mainly stimuli-responsive liposomes. The pH-sensitive liposomes contain pH-sensitive lipids such as l,2-dioleoyl-vn-3-phosphatidylethanolamine (DOPE) showing an inverted hexagonal configuration in a low-pH environment and release entrapped drugs in the low-pH environment of tumor tissues due to liposomal membrane destabilization [89], Temperature-sensitive liposomes are prepared from special lipids such as DPPC whose phase transition temperature (Tc = 41°C) is proper to perform clinical anticancer therapy. When up to Tc, the fluidity of liposomal membranes increases sharply, followed by... 

Membrane fluidity is determined by following anisotropic rotation of fluorescent or spin probes. Liquid-crystalline (or fluid) to gel thermotropic phase transition of lipids (Figure 1) (cf. Section 3.1.1 l)in liposomes or intact biomembranes can be followed by Fourier transform infrared (FTIR) spectroscopy or differential scanning calorimetry (DSC). 

Kusumi et al. [42] published Tj values of several nitroxide membrane probes dissolved in liposomes of dimyristoylphosphatidylcholine as a function of 1/T (see Fig. 3). The dotted lines indicate the pre- and main phase transition temperatures. The relaxation times change at the phase transition temperature, and therefore reflect an aspect of membrane fluidity. It is notable that they change by only about a factor of 3 over a very wide range of conditions. 

Phelan, A. M. and Lange, D. G. (1991) Ischemia-reperfusion-induced changes in membrane fluidity characteristics of brain capillary endothelial cells and its prevention by liposomal-incorporated superoxide dismutase. Biochim. Biophys. Acta 1067, 97-102. 

Suwa, K., Kimura, T., and Schaap, A.P. (1978) Reaction of singlet oxygen with cholesterol in liposomal membranes. Effect of membrane fluidity on the photo-oxidation of cholesterol, Photochem. Photobiol., 28 469 473. 

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