Département de chimie moléculaire

We describe herein a novel approach for the fluorescent detection of small mols. using a sandwich-type aptamer strategy based on a signaling macrocyclic host-dye system. One split adenosine aptamer fragment was 5'-conjugated to a $\beta$-cyclodextrin (CD) mol. while the other nucleic acid fragment was labeled at the 3'-end by a dansyl mol. prone to be included into the macrocycle. The presence of the small target analyte governed the assembly of the two fragments, bringing the dye mol. and its specific receptor in close proximity and promoting the inclusion interaction. Upon the inclusion complex formation, the microenvironment of dansyl was modified in such a way that the fluorescent intensity increased. Concomitantly, this supplementary interaction at the aptamer extremities induced stabilizing effects on the ternary complex. We next proposed a bivalent signaling design where the two extremities of one split aptamer fragment were conjugated to the $\beta$-CD mol. while those of the other fragment were tagged by the dansyl dye. The dual reporting dye inclusion promoted an improvement of both the signal-to-background change and the assay sensitivity. Owing to the vast diversity of responsive host-macrocycle systems available, this aptasensor strategy has potential to be extended to the multiplexed anal. and to other kinds of transducers (such as electrochem.). [on SciFinder(R)]