Usefulness of cyclodextrins for detection in molecular fluorescence. Application to xenobiotics and drugs

Cyclodextrins (CDs) present the unique ability to entrap molecules. In analytical chemistry, they have been mainly used for separation purpose. The present review deals with their potential interest towards the detection by molecular fluorescence of the included compounds mainly xenobiotics and drugs. As some of the included molecules exhibit native fluorescence due to their aromaticity, the addition to their aqueous solution of CDs entails, in some cases, a large enhancement of their emission of fluorescence. This feature appears of particular interest from an analytical point of view, either for direct detection of the guest molecule or as a detection mode after separations techniques (i.e.: chromatography or electrophoresis). Decrease in rotation motion of entrapped molecule and (or) decrease in solvent relaxation appear as the main causes of the enhancing emission effect. Some example picked up from pharmaceutical and bioanalytical literature are presented in order to demonstrate the interest of CDs in the field of the fluorescence techniques.