Liposomes have attracted much attention since they were first discovered. These artificially created, microscopic spheres have many properties that make them extremely useful. One of these is their bio-compatibility. They act in exactly the same way as the cellular membranes of the body. This means they can be used as a unique delivery system for nutrients, drugs and other agents to specific areas in an organism. There are a numbers of ways in which liposome manufacturing is achieved, all of which have advantages and disadvantages.
Phospholipids like lecithin is used as raw material. The phospholipid molecules have heads that love water. They also have two tails that are essential fatty acid chains repelled by water. When the phospholipids are put in a solution that is water-based, the heads end up side by side with the tails trailing behind. The fact that the tails repel water means that another layer lines up with the tails facing the tails of the first layer. This natural alignment results in two rows of tightly fitting molecules. These layers form membranes around and inside all cells.
Liposomes can be used as delivery vehicles for a wide variety of drugs, vaccines, enzymes, genetic material and for some nutritional supplements as well. They not only allow for release of encapsulated materials but are beneficial in themselves for cells. The lipids used to construct the fatty part of the molecule is used by the cell wall for repair and construction of new membranes.
The tiny size of liposomes means they are quickly assimilated into the bloodstream for delivery throughout the body. The payload is biologically inert until it is delivered to needy cells. They are all basically the same but the differences between them occur in the way they are released, how long this takes as well as where and why this occurs.
Liposomes are usually synthesized by mixing and dissolving phospholipids in organic solvent. A clear lipid film is formed by removing the solvent. Hydration of this film eventually leads to formation of large vesicles which have several layers, much like the structure of an onion. Each bilayer is separated from the other by water. A form of energy is required to reduce their size. Sonication, agitation by sound waves, is one method used and extrusion is another.
So, the general elements consist of lipid preparation for hydration, hydration with agitation and then sizing of vesicles. Each different method used has certain advantages and disadvantages. Liquid hydration methods usually result in low dose loading. Sonication can affect the structure of an encapsulated drug.
Some of the problems associated with these processes are inconsistencies in size, structural instability and high costs. These problems are all receiving attention and solutions are being found. Cosmetology, for example, is benefiting from the production of tiny particles called nanosomes which are much, much smaller than normal liposomes and can therefore penetrate the skin more easily.
One of the greatest benefits of liposomes is there flexibility. They can be adapted in many different ways to suit different applications. Size, surface charge and lipid content can all be varied according to the techniques used. Conventional methods are effective but much experimentation is still being done. The future holds many new possibilities with the exciting developments taking place in this field.
Phospholipids like lecithin is used as raw material. The phospholipid molecules have heads that love water. They also have two tails that are essential fatty acid chains repelled by water. When the phospholipids are put in a solution that is water-based, the heads end up side by side with the tails trailing behind. The fact that the tails repel water means that another layer lines up with the tails facing the tails of the first layer. This natural alignment results in two rows of tightly fitting molecules. These layers form membranes around and inside all cells.
Liposomes can be used as delivery vehicles for a wide variety of drugs, vaccines, enzymes, genetic material and for some nutritional supplements as well. They not only allow for release of encapsulated materials but are beneficial in themselves for cells. The lipids used to construct the fatty part of the molecule is used by the cell wall for repair and construction of new membranes.
The tiny size of liposomes means they are quickly assimilated into the bloodstream for delivery throughout the body. The payload is biologically inert until it is delivered to needy cells. They are all basically the same but the differences between them occur in the way they are released, how long this takes as well as where and why this occurs.
Liposomes are usually synthesized by mixing and dissolving phospholipids in organic solvent. A clear lipid film is formed by removing the solvent. Hydration of this film eventually leads to formation of large vesicles which have several layers, much like the structure of an onion. Each bilayer is separated from the other by water. A form of energy is required to reduce their size. Sonication, agitation by sound waves, is one method used and extrusion is another.
So, the general elements consist of lipid preparation for hydration, hydration with agitation and then sizing of vesicles. Each different method used has certain advantages and disadvantages. Liquid hydration methods usually result in low dose loading. Sonication can affect the structure of an encapsulated drug.
Some of the problems associated with these processes are inconsistencies in size, structural instability and high costs. These problems are all receiving attention and solutions are being found. Cosmetology, for example, is benefiting from the production of tiny particles called nanosomes which are much, much smaller than normal liposomes and can therefore penetrate the skin more easily.
One of the greatest benefits of liposomes is there flexibility. They can be adapted in many different ways to suit different applications. Size, surface charge and lipid content can all be varied according to the techniques used. Conventional methods are effective but much experimentation is still being done. The future holds many new possibilities with the exciting developments taking place in this field.
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