Impregnation of drugs in biocompatible polymers for slow release

The work involves doing a thorough literature survey on loading biocompatible polymers with drugs for their slow or sustained release.  Loading is done through supercritical carbon dioxide medium; first, the drug dissolves in the medium; then, the medium diffuses through the polymer; the medium and the polymer are kept in contact for a sufficiently long time during which the drug adsorbs in the polymer; finally, the system is depressurized to remove carbon dioxide from the polymer.  One of the goals of this work is to check if any mechanism has been proposed for such loading.  If yes, understand it clearly and carefully.  If not, think about possible mechanisms and ways to establish them.  If time permits, a model could be proposed or a few experiments could be conducted