Liposome complex formation

Similarly comb-like copolymers of vinyl pyrollidone and vinyl alkyl amines were shown [446] to influence the permeability of negatively charged phospholipid liposomes containing encapsulated carboxyfluorescein. At a pH of approximately 7, the copolymers allowed permeability and solute release due to polymer/liposome complex formation and disruption of the phospholipid membrane. 

YO-YO is supplied as a 1 mM solution in DMSO, which is added to the plasmid at approx 1 100 dye base pair ratio. At this ratio, sensitivity is high and DNA/ liposome complex formation is compromised very little. 

Sternberg, B., Sorgi, F.L., and Huang, L., New structures in complex formation between DNA and cationic liposomes visualized by freeze-fracture electron microscopy, FEBS Letters, 1994, 356, 361-366. 

Gershon H, Ghirlando R, Guttman SB, Minsky A. Mode of formation and structural features of DNA-cationic liposome complexes used for transfection. Biochemistry 1993 32(28) 7143-7151. 

To bridge this gap, liposomal transfection efficiency can be dramatically enhanced by the inclusion of peptides into the complex without increasing immunogenicity. Peptides can be selected to assist lipofection at each key stage of the process complex formation, cell targeting and uptake, endosomal disruption, and nuclear targeting. The purpose of this chapter is... 

Figure 1 Potential points for the enhancement of liposome-mediated gene transfer. The above diagram illustrates the characteristic lipofection pathway demonstrating the four key stages bold, underlined), complex formation, targeting and internalization, endosomal escape, and nuclear translocation. Indicated alongside (italic) are the peptides that can be used to augment the transfection potential of the liposome. Abbreviation pDNA, plasmid DNA.

Rytomaa, M., and Kinnunen, P.KJ., 1995, Reversibility of the binding of cytochrome c to liposomes. Implications for lipid-protein interactions. /. Biol. Chem., 270 3197-3202 Salamon, Z., and Tollin, G., 1996, Surface plasmon resonance studies of complex formation between cytochrome c and bovine cytochrome c oxidase incorporated into a supported planar lipid bilayer. II. Binding of cytochrome c to oxidase-containing cardiolipin /phosphatidylcholine membranes. Biophys. J., 71 858-867 Salamon, Z., and Tollin, G., 1997, Interaction ofhorse heart cytochrome c with lipid bilayer membranes effects on redox potentials. J. Bioenerg. Biomembr. 29 211-221 Scarlett, J.L., and Murphy, M.P., 1997, Release of apoptogenic proteins from the... 

Direct gene transfer into the respiratory system can be carried out for either therapeutic or immunization purposes. Cells in the lung can take up and express plasmid DNA whether it is administered in naked form or formulated with cationic liposomes. For a given dose of DNA, the results can be improved when the DNA is mixed with the minimum amount of lipid that can complex it completely. Such a complex formation can be considered a formation of microparticles that can enhance cellular uptake and subsequent immune responses. 

Key words Cationic liposome, siRNA, pDNA, Complex formation, siRNA-lipoplex, pDNA-lipoplex,... 

It is not recommended to use culture medium in cationic liposome concentrated stock. They are composed of a mixture of essential salts, nutrients, and buffering agents that will inhibit the complex formation ability of siRNA and pDNA. 

Fig. 1. Effect of vortex speed (2,500 rpm for 10 min) on the luciferase gene siiencing efficiency of a siRNA-LipoTrusf lipoplex in HeLa cells. The amount of cationic lipid was 9.6 aM. The siRNA doses correspond to the cationic Npid+/siRNA- charge ratio of 30.45, 15.24,7.62,3.81,1.90 and 0.95, respectively. LipoTrusf is constituted of dioleoylphos-phatidylethanolamine, cholesterol and the cationic lipid 0,0 -ditetradecanoyl-/V-(a-trimethyl ammonioacetyl) diethanolamine chloride (DC-6-14) in the molar ratio of 0.75/0.75/1.00. For this cationic liposome, an expressive gene silencing effect in vitro was obtained at lower siRNA dose with application of a higher vortex-mixing during complex formation...

Gershon H, et al. (1993). Mode of formation and strnctnral featnres of DNA-cationic liposome complexes nsed for transfection. Biochem. 32 7143-7151. 

The release of active compounds from liposomes is directly related to liposomal bilayer stability. Therefore, a controlled-release profile from CyD-containing liposomes is difficult to obtain because of interaction between inclusion complexes and the hpidic vesicle (cholesterol and phospholipids) [103]. Indeed, lipid/CyD complex formation can occur within the hposomes, thus destabilizing the liposomal bilayer [85]. Liposome destabilization is also closely related to the stability of the encapsulated complex the higher the affinity between drug and CyD, the slower the drug release [84]. 

The properties of supported enzyme preparations are governed by the properties of both the enzyme and the carrier material. The interaction between the two provides an immobilized enzyme with specific chemical, biochemical, mechanical and kinetic properties. The support (carrier) can be a synthetic organic polymer, a biopolymer or an inorganic solid. Enzyme-immobilized polymer membranes are prepared by methods similar to those for the immobilized enzyme, which are summarized in Fig. 22.7 (a) molecular recognition and physical adsorption of biocatalyst on a support membrane, (b) cross-linking between enzymes on (a), (c) covalent binding between the biocatalyst and the membrane, (d) ion complex formation between the biocatalyst and the membrane, (e) entrapment of the biocatalyst in a polymer gel membrane, (f) entrapment and adsorption of biocatalyst in the membrane, (g) entrapment and covalent binding between the biocatalyst and the membrane, (h) entrapment and ion complex formation between the biocatalyst and the membrane, (i) entrapment of the biocatalyst in a pore of an UF membrane, (j) entrapment of the biocatalyst in a hollow-fiber membrane, (k) entrapment of biocatalyst in microcapsule, and (1) entrapment of the biocatalyst in a liposome. 

Microcapsule production Microparticle formation Melt extrusion Melt injection Complex formation Liposomes Micelles... 

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