Complexation by CDs and Release

The lipophilic bucket of CDs allows physical binding of encapsulants primarily through hydrogen bonding. On the other hand, it has active primary and secondary hydroxyl groups which allow chemical modification or ionic interaction (only pH 12) for preparation of conjugates or crosslinked products [3,10,11]. Furthermore, some smaller compoxmds can be solubilized in fraction in the lipophilic bucket, and larger compounds are solubilized by complexation with two CD molecules as well. But this complexation is concentration dependent because this is an affinity-dependent dynamic process. In addition, steric and ionic compatibility is an important criterion for encapsulation, rather than phase of CD and encapsulant. 

Significant research has been carried out to illustrate the thermodynamics and forces that drive encapsulation. However, classical principles of thermodynamics fail to explain the inconsistency in results. To better understand the forces that drive the encapsulation process and evaluate the role of hydrophobic interaction in the process of encapsulation, Taulier et al. studied alteration in volume, expansibility or adiabatic compressibility obtained due to encapsulation of AD and p-CD. They reported that upon encapsulation, 20-25 water molecules were displaced from the hydrophobic regions of both AD and P-CD, which was further evidenced by the number of water molecules in the bulk. These 

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