LIFETIME-BASED SENSING OF GLUCOSE USING ENERGY-TRANSFER WITH A LONG LIFETIME DONOR

We describe an optical assay for glucose based on the luminescence dec ay time of a long lifetime metal-ligand complex. Concanavalin A was co valently labeled with Ruthenium metal-ligand complex (RuCon A) which s erved as the donor. The acceptor was malachite green which was covalen tly linked to insulin. The malachite green insulin was also covalently labeled with maltose (MIMG) to provide binding affinity to RuCon A. B inding of RuCon A to MIMG resulted in a decreased intensity and decay time of RuCon A. Glucose was detected by competitive displacement of M IMG from RuCon A, resulting in increased intensity and decay time. Thi s glucose assay has several favorable features. The long lifetime of R uCon A allows phase-modulation decay time measurements using an amplit ude-modulated blue-light-emitting diode as the light source, Reversibi lity of the assay can be controlled by the extent of sugar labeling of the insulin. Finally, the glucose-sensitive range can be adjusted by selection of the sugar structure and extent of labeling of the insulin . (C) 1997 Academic Press.