One system with two fluorescence resonance energy transfer (FRET) assembles among quantum dots, gold nanoparticles and enzyme

Two fluorescence resonance energy transfer (FRET) assembles between luminescent quantum dots (QDs) and chymotrypsin, QDs and gold nanoparticles (NPs) in one system were firstly studied in this work. With chymotrypsin as the bridge, QDs donors transferred energy to gold NPs with a significant quenching of the emission intensity of CdTe QDs. At the same time, CdTe QDs could also serve as an acceptor in QDs–chymotrypsin assemble, which was confirmed by an obvious decrease of chymotrypsin fluorescence intensity at 350 nm and the enhancement of emission of CdTe QDs. Results from the two FRET assembles showed a clear dependence of the transferring efficiency on the spectrum overlap between donor and acceptor and these data exhibited a great potential of FRET system for the development of new homogeneous binding assays.