Encapsulated model

Fig. 12.1 Main structural models of graphene-metal oxide hybrids, (a) Anchored model oxide particles are anchored to the graphene surface, (b) Encapsulated model oxide particles are encapsulated by graphene, (c) Sandwich-like model graphene is sandwiched between the metal oxide layers, (d) Layered model a structure composed of alternating layers of oxide nanoparticles and graphene, (e) Mixed model graphene and oxide particles are mechanically mixed and graphene sheets form a conductive network among the oxide particles. Red metal oxide Blue graphene. Reprinted with permission from [41]. Copyright 2012, Elsevier B.V.

Debenedetti and coworkers (88,89) provided one of the first examples of microencapsulation of a drug in the polymeric matrix. Richard and coworkers (90) provided a recent example of the microencapsulation process when they produced microparticles with the encapsulated model protein that showed sustained release. Foster and coworkers (87) also reported precipitation of copper-indomethacin by PVP with a 96-fold enhancement in the dissolution rate of indomethacin. These examples clearly demonstrated the advantages of using supercritical fluid processing for the preparation of polymer-drug formulations with potentially improved therapeutic properties. 

The amount of encapsulated model drug (retinyl acetate or progesterone) per mg of dried LS was determined through solubilization of LS in ethyl acetate at 60°C. Following filtration, the solution was analyzed by reverse-phase high-performance liquid chromatography (HPLC) to find the drug content. 

Fig. 7.11 Typical drug release profile of gas- and drug-filled microcapsule formulations. Percent release of an encapsulated model drug in physiological buffer media as a function of time. Storage under stirring for about 100 min at 37°C shows that just a baseline concentration of free drug is...

PHB microcapsules with encapsulated model drug - methylene green have already been reported. The prospects for development and investigation of systems with biological activity based on microcapsules from polyhydroxyal-kanoates look bright. 

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