Investigation of a Fluorescence Signal Amplification Mechanism Used for the Direct Molecular Detection of Nucleic Acids
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A fluorescence signal amplification mechanism allowing detection limits for DNA in the zeptomolar range was investigated. Photophysical properties of the molecular system were studied in order to better explain the signal amplification that is observed. We show that the confinement of a fluorescent DNA hybridization transducer in aggregates improves its quantum yield and photostability. Furthermore, we show that the combination of the resonance energy transfer occurring within the aggregates with the use of a conjugated polymer as the hybridization transducer and donor allows ultrafast and efficient energy coupling to the aggregates and can lead to the excitation of a large number of acceptors by only one donor.
KeywordsFluorescence signal amplification Fluorescence resonance energy transfer Ultrasensitive DNA detection Orientation and confinement in aggregates Ultrafast energy transfer
The authors would like to thank Drs. B. Simard and S. Denommée at the Steacie Institute for Molecular Sciences, NRC, Ottawa, Canada, for the lifetime measurements and Dr. H.A. Ho (U. Laval) for the gift of the polymeric transducer and fruitful discussions. K.D. also acknowledges the Natural Sciences and Engineering Council of Canada for a scholarship.