Liposome Homogenization

Pharmaceutical and Cosmetic application

Liposomes have size and physical characteristics similar to an emulsion.

Liposomes are closed, spherical shells containing aqueous solution; the shell is made by one or more lipid bilayers. A lipid is any type of molecule soluble in organic solvents such as chloroform and ether. The type of lipid associated with liposomes is a phospholipid.

The phospholipid molecule has a water-soluble end and an oil-soluble end, and an example of a phospholipid is lecithin in egg yolk.

The double layer is composed of two monolayers of phospholipisd with the non- polar (oil-soluble) molecular ends facing inward and with the polar ends of both monolayers facing out. The liposome vesicle can be made up of a single bilayer or multiple bilayers. They are described with respect to size and number of layers (lamella):

The importance of liposomes lies in the fact that they can be used as carriers for drugs, enzymes and other biologically active molecules. These active ingredients are encapsulated in the liposome and are transported by these vesicles to different organs in the body.

Liposome vesicles can be prepared with different methods:

Even though liposomes are expensive to prepare, usually because of the high cost of ingredients and the small sample size (2ml), their potential importance and usefulness have led researchers into the development of larger batches.

The homogenizing process:

Product:	Liposomes
Composition:	Water, sodium salicylate, phospholipids
Application:	cosmetic and pharmaceutical
Advantages of Homogenization:	Before the treatment the product was separated in two phases: fat and water. After the high pressure homogenization it's possible to obtain a stable emulsion, reducing the mean size of the fat droplets.
Homogenizer:	Panda NS1001L
n° Stage:  1 Valve 1st:  1 Suggested pressure:  1000 bar x2 pass Suggested temperature:  65 + 70 °C
Options:
Potential clients:	cosmetical industries

In order to prepare liposomes of smaller diameter (about 110 nm), the suitable homogenizing pressure is very high, about 1000-1500 bar and we normally need multiple passes (about 3) to obtain a narrow size distribution.

Effect of the homogenization on the particle size reduction

The results obtained can be checked utilizing different analysis technologies : electron microscopy, light scattering and dynamic light scattering such as performed with a Coulter analyzer.

Homogenizer:

The homogenizer used for the treatment is a machine designed for 1200 bar for

• Very high pressure (VHP)
• High abrasion
• Pharmaceutical applications

The Niro Soavi homogenizers suitable for very small production, can be used successfully for bigger scale preparation of liposome vesicles larger batches.