Cascaded FRET in Conjugated Polymer/ Quantum Dot/Dye-Labeled DNA Complexes for DNA Hybridization Detection

G. JIANG; A. S. SUSHA; A. A. LUTICH; F. D. STEFANI; J. FELDMANN; A. L. ROGACH

ACS NANO

AMER CHEMICAL SOC

Año: 2009 vol. 3 p. 4127 - 4131

1936-0851

Electrostatic complexes of a water-soluble fluorescent conjugated polymer, poly[9,9-bis(3=-((N,N- dimethyl)-N-ethylammonium)propyl)-2,7-fluorene-alt-1,4-phenylene]dibromide (PDFD), and water-soluble CdTe quantum dots (QDs) are designed to provide a cascaded FRET for DNA hybridization detection. PDFD has two functions in the detection scheme: as a light-harvesting antenna, it enhances the emission of QDs by the first level FRET and inverts the sign of the surface charge of QDs, thus providing a positively charged surface to allow negatively charged dye-labeled DNA to interact with the resulting complex. This interaction causes the second level FRET to infrared-emitting dye labeled on the probe DNA, providing a reliable signal-on sensing platform discriminating between complementary and non-complementary DNA. A detailed spectroscopic study offers a clear description of photophysical processes in the designed polymer/QD/DNA complex, providing ample potential for further sensitivity and selectivity improvements.