Fluorescent sensors for the detection of glucosamine and thiaminase

Abstract

[ACCESS RESTRICTED TO THE UNIVERSITY OF MISSOURI AT AUTHOR'S REQUEST.] Fluorescence chemical sensing is a highly important tool in science and industry with many applications in pharmaceutical screening, cell respiration, biological process control as well as biological isolation. Discussed herein is a brief introduction to bioanalyte detection using novel fluorescent chemical sensors for important biomolecules. First, a new fluorescent chemical sensor for glucosamine is reported. The sensor is based on a boronic acid-containing coumarin aldehyde and shows excellent selectivity for glucosamine by forming a boronic ester with the sugar diol as well as an iminium ion with the amine group of glucosamine. The sensor successfully discriminates glucosamine over other similar biomolecules in terms of both fluorescence intensity and binding affinity. This method provides a new concept for the design and synthesis of very selective turn-on optical sensors for selective detection of multi-functional biomolecules. Second, two new fluorescent molecules have been developed for thiaminase: one used to measure thiaminase activity and the other one used to inactivate this interesting enzyme. The thiaminase sensor was designed based on a PET mechanism. The internal quenching of the fluorophore (6Hex) by the attachment of a pyrimidine group makes it non-emissive. Under the action of thiaminase (representative by bisulfite), the free pyridine is released, which results in an increase in fluorescence. In addition to the thiaminase sensor, a red fluorescent, selective, irreversible inhibitor has also been synthesized. The inactivation of this interesting molecule has been confirmed by both plate assays and fluorescent experiences. Inactivation was found to go to completion if given sufficiently long incubation, and to be irreversible.