Alginate-encapsulated liposomes

Figure 5. Release from alginate-encapsulated liposomes. In vitro experiments were performed as follows Encapsulated liposomes were suspended in 10 ml of physiological saline in a screw-capped vial. In cylindrical polypropylene mesh cages (mesh size 105u the mesh was obtained from Fisher Scientific, cut into 2x2.5 inch rectangles, sewn up the side with nylon thread, and sealed at the bottom with a wax plug). Release was at 37°C on a rotary shaker. The encapsulated liposomes were frequently transferred to vials containing fresh buffer in order to mimic the infinite sink conditions of the body.

In the area of controlled release, the preparation of indomethacin sustained-release microparticles from alginic acid (alginate)-gelatin hydrocolloid coacervate systems has been investigated. In addition, as controlled-release systems for liposome-associated macromolecules, microspheres have been produced encapsulating liposomes coated with alginic... 

Potential of alginate-loaded liposomes as a vehicle for the oral delivery of bioactive proteins. The vesicles were prepared from the phospholipid dipalmatoyl phosphatidylcholine using a simple dry film hydration technique. Alkaline phosphatase (ALP) was used as a model bioactive protein. ALP activity following 2 h of exposure to simulated gastric pH was maintained at a significantly higher level (80%) when encapsulated in the alginate-loaded liposomes as compared to ALP loaded in conventional liposomes (55%)... 

Smith AM, Jaime-fonseca MR, Grover LM, Bakalis S (2010) Alginate-Loaded liposomes can protect encapsulated alkaline phosphatase functionality when exposed to gastric ph. J Agric Food Chem 58 4719 724... 

In the dual liposome-microcapsule system, two factors control the release of the active substance escape from lipsomes into the microcapsule interior, and diffusion across a rate limiting capsule wall into the external environment. This system can take advantage of the inherent instability of some lipsomes while over-coming many of the problems associated with their use by protecting them from the environment by the capsule. At the same time, a new measure of control over the time at which a microcapsule will commence delivery of the enclosed agent is introduced by careful choice of the liposome composition. By changing the nature of the liposomes or of the encapsulant (e.g. alginate) different release times and patterns can be obtained. 

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