Distearoyl phosphatidyl

Rabinovici R, Rudolph AS, Feuerstein G. Improved biological properties of synthetic distearoyl phosphatidyl choline-based liposome in the conscious rat. Circ Shock 1990 30 207. 

The preformed vesicle (PFV) approach involves incubation of liposomes containing a cationic lipid and a PEG coating with polynucleotides in the presence of ethanol. Typically, LUV composed of distearoyl-phosphatidyl-choline (DSPC), cholesterol (Choi), l-0-(2 -(oi-methoxy-polyethylene-glycol)... 

Encapsulation efficiencies are listed as a function of ethanol concentration for distearoyl-phosphatidyl-choline/choles-terol/l,2-dioleoyl-3-dimethylammoniumpropane large unilamellar vesicle (LUVs). The initial oligonucleotide-to-lipid ratio was 0.034 mol/mol (0.3mg/mg). The LUVs used for these experiments were 99 22 nm in size. The encapsulation values are given as mean SD. 

Figure 2 Encapsulation as a function of ethanol concentration. Oligonucleotides were added to distearoyl-phosphatidyl-choline/cholesterol/l-0-(2 -(co-methoxy-poly-ethylene-glycol)succinoyl)-2-iV-myristoyl-sphingosine /1,2-dioleoyl-3-dimethylam-monium propane liposomes in varying concentrations of ethanol at an initial oligonucleotide-to-lipid ratio of 0.24mg/mg. Abbreviations AS, antisense oligonucleotide %EtOH(v/v), percentage of ethanol in volume/volume.

Recently, this method was adapted to label two commercially available liposomal formulations doxorubicin encapsulated in polyethylene glycol (PEG)-coated liposomes (Caelyx /Doxil ) (14) and daunorubicin encapsulated in small distearoyl-phosphatidyl-choline/cholesterol liposomes (Daunoxome ) (15). Although no DTPA was encapsulated in these liposomes, the labeling efficiency was typically between 70% and 80% and the radiolabeled preparations were stable in vivo during the time course of the experiment (four hours). Most likely, the lipophilic In-oxine avidly associates with the lipid bilayer and encapsulation of DTPA might not be necessary when the experimental observation period does not exceed four to six hours. 

Figure 3.12 shows how the r(aj)-isotherm is affected when the number of the hydrocarbon chains in the surfactant molecule is doubled. A monolayer of cationic-anionic surfactant pairs, behaves phenomenologically as if it consisted of double chain molecules in the condensed phase the molecular eirea more or less doubles as compared to single chains. For the distearoyl phosphatidyl choline the more bulky phosphate head group further increases the cross-sectional area per molecule. This is consistent with some tilt in the orientation of the molecules with respect to the normal of the interface (cf. sec. 3.3b, ad (iv)). 

Phospholipids Soybean lecithin Egg lecithin Diolelyl phosphatidyl choline Distearoyl phosphatidyl glycerol PEGylated phospholipids Dimyristoyl phosphotidyl choline All routes... 

L-Distearoyl-a-phosphatidyl- XII/2, 266f. (Hydroxy-phenoxy-phosphoryl)-(N-benzyloxy-car-bonyl)- -benzylester XII/2, 267 L-a-Phosphatidyl-L- XII/2, 266 N-Phospho- XII/2, 184f 194, 206... 

Egg phosphatidylcholine (PC), distearoyl phosphatidylcholine (DSPC), phospha-tidic acid (PA), and phosphatidyl glycerol (PG) (more than 99% pure) were from Lipid Products Nutfield. All other phospholipids (more than 98% pure), cholesterol, triolein (TO), stearylamine (SA), fluorescein isothiocyanate (FITC), and oil red O were from Sigma Chemical Company. Sepharose CL-4B and polyethylene glycol 6000 were obtained from Pharmacia. All other reagents were of analytical grade. 

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