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Reversible Encapsulation

Final Activity Report Summary - RevEncap (Reversible Encapsulation)

This project was the first step towards a reversible drugs’ encapsulation approach, whereby stable capsules were assembled by dynamic combinatorial chemistry (DCC) based on disulfide or hydrazone exchange. Our aim was to develop an original and promising drug delivery method to assemble specific capsules that would release their guest molecules, i.e. drugs, under the influence of a physiologically relevant trigger.

The first step was to make mixtures of building blocks to generate different cage-like structures under equilibrium, held together by reversible covalent bounds such as disulfide or hydrazone bonds (dynamic combinatorial libraries). The available building blocks were very limited. Therefore, I synthesised new trithiol building blocks to produce a capsular structure as well as new building blocks based on hydrazone reversible covalent chemistry. Such building blocks required diverse functionalities e.g. aromatic or hydrophobic surfaces for guest recognition and water solubilising moieties. The combination of all these functionalities made the building blocks’ syntheses a real challenge.

I also explored the use of the different obtained building blocks in order to produce with success a capsular structure in solution. Some of them led to the formation of capsules, which was an important achievement. Then I studied the introduction of a guest molecule into these building blocks mixtures that could lead to the stabilisation and amplification of a selective capsule that could accommodate this guest. No amplification was observed for the capsules based on disulfide exchange. These studies were still in progress, by the time of the project completion, in the host research group for the capsules formation based on hydrazone exchange.