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Wednesday, 1 October 2014

Methods And Techniques For Liposome Manufacturing

By Jody Leach


Liposomes are microscopic spheres made from the same material as the cell membranes in the human body. They have attracted a lot of attention due to their amazing properties. They can be used to carry drugs, nutrients and other agents to specific destinations in the body. There are various different preparation methods and techniques for liposome manufacturing and those used depend on on various factors.

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.

Liposomes are used to deliver toxic drugs to target cancer cells. They are used for delivering nutrients deficient in the body or cosmetic nutrients to the skin. Many other medical applications are possible too such as in the field of genetics. Preparation methods depend on various factors such as the characteristics of the material to be carried, the consistency offered from batch to batch and scale of production.

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.

All the methods for preparation of liposomes have the same basic stages. Lipid vesicles are formed when thin lipid films are hydrated. The liquid bilayers become fluid, detach and self-close to form large vesicles. Once these large particles have formed, their size is reduced by energy input. This may be in the form of sonic energy called sonication or mechanical energy called extrusion.

Liposomes are actually fairly simple to make, not requiring complex materials, equipment or methods. Each method and technique offers certain benefits and has some failings. Sonication can cause structural changes to what is entrapped. Liquid hydration methods do not produce a high payload.

The type of manufacturing processes and equipment used both have an effect on the type of liposomes produced. Inconsistent sizes, high production costs and structural instability are just some of the challenges faced in production. Many advances are being made in this respect as research proceeds at a rapid pace. An exciting example is research into how to make liposomes that can target certain organs or diseased tissue.

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.




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