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. Author manuscript; available in PMC: 2010 Apr 1.
Published in final edited form as: Nano Today. 2009 Apr 1;4(2):125–134. doi: 10.1016/j.nantod.2009.02.008

Figure 1.

Figure 1

(a) Schematic of two-step QD-FRET. Excitation of the QD donor drives stepwise energy transfer (E12) through the nuclear dye (ND) which serves as the first acceptor/donor (or relay) for energy transfer to the second acceptor Cy5 (E23). (b) Plasmid DNA is double-labeled with QD and nuclear dyes before complexation with a Cy5-labeled cationic polymer to form nanocomplexes by self-assembly. Three distinct states of plasmid DNA (pDNA): (I) condensed within a nanocomplex, (II) released and intact, and (III) degraded, are distinguished by relative ND and Cy5 emission and calculated E12 and E23 efficiencies.