Liposome mean diameter

A recent XRD study of CL/DNA complexes has revealed that the addition of linear lambda-phage DNA (48, 502 bp, contour length=16.5 pm) (Raedler et al., 1997) or plasmid DNA (Lin et al., 2000) to binary mixtures of cationic liposomes (mean diameter of 70 nm), consisting of mixtures of neutral lipid DOPC and cationic DOTAP, induces a topological transition from liposomes into collapsed condensates in the form of optically birefringent liquid crystalline (LC) globules with sizes on the order of 1pm. 

Figure 19.4 Liposome mean diameter measured by light scattering versus the combined fluid flow velocities of all i I PA inlet velocity is 2.4 mm s [51].

FIGURE 1 Effect of (sequential) extrusion of MLV dispersions through polycarbonate membrane filters (Unipore) with pore sizes of 1.0, 0.6, 0.4, 0.2, and 0.1 ym on the mean liposome diameter. DXR-containing MLV (phosphatidylcholine/phosphatidylserine/ cholesterol 10 1 4) mean diameter of nonextruded dispersion about 2 ym pH 4. Mean particle size determined by dynamic Light scattering (Nanosizer, Coulter Electronics). (From Crommelin and Storm, 1987.)... 

FIGURE 3 Effect of the amount of cholesterol on the particle size. Phosphatidylcholine/cholesterol liposomes were prepared by the octyl glucoside dilution technique. The begin concentration of the mixed micelles was 150 mM octyl glucoside and 10 mM phosphatidylcholine in 10 mM tris(hydroxymethyl)aminomethane and 0.9% NaCl, pH 7.4. Dilution was performed with an automatic titration unit at a dilution rate (= dilution factor, relative to the initial volume, per unit of time) of 0.026 sec"l ( a and ) or 0.69 sec l ( and o). Mean diameters after dilution and ) and after filtration ( L and q) are repi sented. (Adapted from Jiskoot et al, 1986a.)... 

Liposome size can range from around 20 nm to around 50 pm. To a certain extent, the mean diameter and distribution of the diameters can be controlled by sizing procedures after the formation of the initial liposome dispersion or by a careful selection of the preparation conditions (cf. Sec. II). Several techniques can be used to determine mean particle size and particle size distribution (Groves, 1984). 

FIGURE 9.5 Schematic representation of phospholipids distribution in lipid emulsions and liposomes. Both drug carrier systems show similar surface. The main differences between liposomes and lipid droplets are related to the mean diameter and nature of the inner contents. (From dos Santos, 2005.)... 

Fig. 10.6 Confocal laser scanning microscopy photographs of various parts of the intestinal tract of the rat at 2 h after intragastric administration of ssCS-Lips (taken from Takeuchi et al. 2005a). The measured mean diameter is 281.2 nm. The formulation of liposome is DSPC DCP cholesterol = 8 2 1...

The mean diameter of the liposomes after the initial sonication step and before freezing is 90 30 nm (first column) and increases to 711 105 nm after freezing and thawing in the presence of 0.32 M mannitol. 

By applying the modified one-step liposome-preparation technique (that is described in detail in Subheading 3), several types of plain or mixed ARSL, composed of different lipids and at different ratios (Table 1), some also PEGylated, were prepared and characterized physicochemically (9-12). Vesicle mean diameters and size distributions, vesicle zeta-potential and efficiency to encapsulate hydrophilic substances (e.g. calcein) have been measured, and the physical stability of ARSL was evaluated by measuring their size distribution during extend periods of storage. 

In order to obtain a liposomal population with uniform size distribution, extrude liposomes through polycarbonate filters with pore size of 100 nm using a handle liposomal extruder (Avestin Inc., Canada). Usually 31 cycles of extrusion through the filter is sufficient for obtaining homogenous populations of liposomes with polydispersity index below 0.1 and mean diameter around 120 nm. 

Folate-targeted LPD-II particles were generated by mixing anionic liposomes composed of DOPE/cholesteryl hemisuccinate (CHEMS)/ folate-polyethyleneglycol (PEG)-DOPE and the cationic DNA-polylysine (1 0.75, w/w) complexes. Structural analysis of LPD-II by negative-stain EM showed that the DNA-polylysine (which appears individually as rod shaped) and lipid complex seemed to be a highly electron dense, spherical core with a low-density coating. The mean diameter of these particles was 74 14 nm, i.e., smaller than the empty liposomes. 

Assessment of the mean diameter of the liposomes is performed under ambient conditions on a Nicomp submicron particle sizer (Model 270, Pacific Scientific, Santa Barbara, CA) with the laser operating at 200 kHz and a wavelength of 632.8 nm, and the external and scattering angle fixed at 90°. 

Virosomes are liposomal carriers for antigens consisting of unilamellar vesicles with a mean diameter of 150 nm (approximately the size of a real virus) they are now commercially available for hepatitis and influenza vaccination. ... 

During the preparation procedure of the samples for SEM, certain deviations from the values of the mean vesicle diameters are possible. Referring to a liposome dispersion standard sample (Natipide II), it was concluded that the values of the vesicle diameters are in agreement with the standard sample diameter values within the standard deviation. This could be acceptable, for the aim of this paper was to investigate this influence of various factors (PRO concentration, homogenization terms) on changes in the mean diameter of liposomes. 

AmBisome . This is a sterile lyophilised liposomal formulation. Each vial contains 50 mg amphotericin B, 194 mg hydrogenated soybean phosphatidylcholine, 84 mg distearoylphosphatidylglycerol and 52 mg cholesterol. Upon reconstitution with sterile water for injection, small unilamellar liposomes that have a mean diameter of 80-100 nm are formed. Adult dose 1-3 mg/kg daily. Amphocil . This is a sterile lyophilised cofioidal dispersion. Each vial contains 50 or 100 mg amphotericin B and sodium cholesterol sulphate approximately equimolar amount. Upon reconstitution with sterile water for injection it forms a colloidal dispersion. Adult dose 1-4 mg/kg daily. 

FIGURE 9 Antitumor activity of liposome-encapsulated cDDP and free cDDP in solid IgM immunocytoma-bearing Lou/M rats. Tumorbearing rats were injected with 2 mg cDDP/kg body weight twice a week (arrow). Tumor diameter at the start of the experiment was 2-3 cm. Tumor growth during treatment is presented (mean SD of six animals unless otherwise indicated). Liposomes DPPC/DPPG/ chol (molar ratio 10 1 10) size about 0.7 pm. PC/PS/chol (molar... 

The recovered liposomes possess a mean geometric diameter of 0.2 p.m. The aerodynamic diameter of these particles, when emitted from an ultrasonic nebulizer, is 1 xm. 

---