Cyclodextrins

Cyclodextrins are crystalline, water soluble, cyclic, non-reducing, oligosaccharides built up from six, seven, or eight glucopyranose units. Cyclodextrins have long been known as products which are able to form inclusion complexes. They have, however, been no more than scientific curiosities due to their limited availability and high price. As a result of intensive research and advances in enzyme technology, cyclodextrins and their chemically modified derivatives are now available commercially, generating a new technology: the packaging on molecular level.

Molecules, or functional groups of molecules being less hydrophilic than water, can be included in the cyclodextrin cavity in the presence of water, if their molecular dimensions correspond to those of the cyclodextrin cavity. The formed inclusion complexes are relatively stable, and rapidly separate from the solution in crystalline form. One two or three CD molecules contain one or more entrapped guest molecules, this is the essence of molecular encapsulation.

Almost all applications of cyclodextrins involve complexation. In many case complexes are separated in more or less pure form and utilized as crystalline substances (drug and flavour complexes) while in other cases the complexation process is only a transient state, and becomes apparent through the final result (CD-catalysis, separation of mixtures, environmental application)

Up to quite recently cyclodextrins were considered exclusively as “empty” capsules of molecular size. Recent studies revealed such a broad versatility in their application, that they can be considered as a new group of industrial basic materials. CDs are besides being “molecular capsules”, reagents in analytical chemistry and diagnostics, basic materials for the production of derivatives and polymers, biologically active substances, etc. For more details see www.cyclolab.hu.