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.
Formation of liposomes is not spontaneous. Lipid vesicles are formed when phospholipids like lecithin are placed in water. Each molecule has a water-loving head and two water-repelling tails. When these molecules are placed in a water-based solution, the heads line up side by side with the tails behind. The fact that the tails are repelled by water means that another layer lines up with the tails facing one another. These two rows form a protective membrane around the cell.
It is possible to customize liposomes for different applications. These applications include delivering drugs to kill cancer cells, transferring DNA to make genetic modifications to cells or delivering cosmetic nutrients to the skin. Preparation method is affected by the application. For example, the concentration and toxicity of drugs used for treating cancer requires a particular preparation method.
Various lipids and mixtures can be used to make liposomes and some of these are of a higher quality than others. What they have in common is they do not go through the digestive tract and the encapsulated payload is not biologically active until it reaches the cells. It is how, when, where and why the rupture of the membrane occurs that the difference between them comes in.
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.
Different methods are known to have certain weaknesses and strengths. Some allow for high load dosing and others offer much lower dose loading. Some of them offer more consistency and stability. The encapsulated content is affected more by some methods than others.
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.
A great benefit involved in using liposomes is that they can be customized for different applications by varying the method of preparation, size, lipid content and surface charge. Many conventional techniques for preparing them and reducing their size are fairly simple to implement and equipment does not have to be too sophisticated. However, novel routes are being discovered for preparation due to motivation to scale-down for point-of-care applications or or to scale-up for industrial applications.
Formation of liposomes is not spontaneous. Lipid vesicles are formed when phospholipids like lecithin are placed in water. Each molecule has a water-loving head and two water-repelling tails. When these molecules are placed in a water-based solution, the heads line up side by side with the tails behind. The fact that the tails are repelled by water means that another layer lines up with the tails facing one another. These two rows form a protective membrane around the cell.
It is possible to customize liposomes for different applications. These applications include delivering drugs to kill cancer cells, transferring DNA to make genetic modifications to cells or delivering cosmetic nutrients to the skin. Preparation method is affected by the application. For example, the concentration and toxicity of drugs used for treating cancer requires a particular preparation method.
Various lipids and mixtures can be used to make liposomes and some of these are of a higher quality than others. What they have in common is they do not go through the digestive tract and the encapsulated payload is not biologically active until it reaches the cells. It is how, when, where and why the rupture of the membrane occurs that the difference between them comes in.
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.
Different methods are known to have certain weaknesses and strengths. Some allow for high load dosing and others offer much lower dose loading. Some of them offer more consistency and stability. The encapsulated content is affected more by some methods than others.
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.
A great benefit involved in using liposomes is that they can be customized for different applications by varying the method of preparation, size, lipid content and surface charge. Many conventional techniques for preparing them and reducing their size are fairly simple to implement and equipment does not have to be too sophisticated. However, novel routes are being discovered for preparation due to motivation to scale-down for point-of-care applications or or to scale-up for industrial applications.