Time-Resolved Analysis of a Highly Sensitive Förster Resonance Energy Transfer Immunoassay Using Terbium Complexes as Donors and Quantum Dots as Acceptors

[摘要] CdSe/ZnS core/shell quantum dots (QDs) are used as efficient Förster Resonance Energy Transfer (FRET) acceptors in a time-resolved immunoassays with Tb complexesas donors providing a long-lived luminescence decay. A detailed decay time analysis ofthe FRET process is presented. QD FRET sensitization is evidenced by a more than 1000-foldincrease of the QD luminescence decay time reaching ca. 0.5 milliseconds, the same value to which the Tb donor decay time is quenched due to FRET to the QD acceptors. The FRET system has an extremely large Förster radius of approx. 100 Å and more than 70% FRETefficiency with a mean donor-acceptor distance of ca. 84 Å, confirming the appliedbiotin-streptavidin binding system. Time-resolved measurement allows for suppression ofshort-lived emission due to background fluorescence and directly excited QDs. By this meansa detection limit of 18 attomol QDs within the immunoassay is accomplished, an improvement of more than two orders of magnitude compared to commercial systems.

[学科分类] 基础医学