Energy transfer from terbium complexes to quantum dots: the advantage of independent donor and acceptor decay time analysis for investigations on FRET distance dependence

Abstract

The efficient use of luminescent semiconductor quantum dots (QDs) as Forster Resonance Energy Transfer (FRET) acceptors can be accomplished with terbium complexes (TCs) as donors. TCs exhibit long excited state lifetimes (in the millisecond range) up to 105 times longer than typical QD lifetimes. When FRET occurs from TCs to QDs the measured TC luminescence decay times decrease (FRET quenching), whereas the QD decay times increase (FRET sensitization). Due to the large difference between the TC and QD excited state lifetimes the FRET formalism can be applied to both the TC donors as well as the QD acceptors. This is a big advantage because the FRET information from one experiment can be received from both sides of the FRET pair allowing for the use of different detection channels and wavelengths for donor and acceptor. Thus, a multiplexing format becomes possible with one single donor (TC) and several different acceptors (different QDs). In this contribution we show the theoretical background for simultaneously applying FRET to donor and acceptor and give an example with a commercially available TC-QD donor-acceptor pair.