Liposphere

All together, these findings have encouraged the development of neutral and cationic lipospheres (CLS) as nonviral DNA-mediated gene transfer techniques because CLS enable the extemporaneous production of pharmaceutical formulations. Like emulsions and liposomes, lipospheres (LS) consist of physiologically well-tolerated ingredients that have often already been approved for pharmaceutical use... 

Composition, Particle Size, Zeta Potential, and Loading Efficiency of Nucleic Acid of the Cationic Lipospheres Considered in the Chapter Zeta Cationic Lipospheres Composition Method of Particle Potential ... 

FIGURE 8.4 Scanning electron micrograph of J774 cells alternatively untreated (A) and treated (B) with cationic lipospheres containing DDAB18. Black arrows indicate internalized submicron particles. Bar corresponds to 10 and 30 4m in panels A and B, respectively. 

Cortesi, R., Esposito, E., Magnan, M., Campi, F., and Nastruzzi, C., Cationic lipospheres for nucleic acid delivery, manuscript in preparation. 

Liposphere The circulation of hydrocarbon-based materials in Titan s atmosphere, which is analogous to the hydrosphere (water cycles) on Earth... 

The C2H polymerisation reaction shown below results in the formation of long-chain hydrocarbon species that form part of the liposphere. 

Although the lipospheres seem to fit very well in vaccine formulations provided by injection or by oral intake, apparently not much has been published in this field since our last review [12], This chapter is an update of the that review, with an emphasis on the possible use of lipospheres for oral immunization. 

In contrast to certain oil emulsions (including Incomplete Freund s Adjuvant), the liposphere approach uses pharmaceutically acceptable biodegradable constituents. 

The internal hydrophobic core of lipospheres is composed of fats and biodegradable polymers, mainly triglycerides and lactide-based polymers, whereas the surface activity of liposphere particles is provided by the surrounding lecithin layer, composed of phospholipid molecules. 

The neutral fats used in the preparation of the hydrophobic core of the several liposphere-vaccine formulations described here included tricaprin and tristearin, stearic acid, and ethyl stearate. The phospholipids used to form the surrounding layer of lipospheres were egg phosphatidylcholine and dimyristoyl phosphatidylg-lycerol. Polymeric biodegradable lipospheres were prepared from low molecular weight polylactide (PLA) and polycaprolactone-diol (PCL). 

Liposphere formulations are prepared by solvent or melt processes. In the melt method, the active agent is dissolved or dispersed in the melted solid carrier (i.e., tristearin or polycaprolactone) and a hot buffer solution is added at once, along with the phospholipid powder. The hot mixture is homogenized for about 2 to 5 min, using a homogenizer or ultrasound probe, after which a uniform emulsion is obtained. The milky formulation is then rapidly cooled down to about 20°C by immersing the formulation flask in a dry ice-acetone bath, while homogenization is continued to yield a uniform dispersion of lipospheres. 

Alternatively, lipospheres might be prepared by a solvent technique. In this case, the active agent, the solid carrier, and the phospholipid are dissolved in an organic solvent such as acetone, ethyl acetate, ethanol, or dichloromethane. The solvent is then evaporated and the resulting solid mixed with warm buffer solution, and mixing is continued until a homogeneous dispersion of lipospheres is obtained. 

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