cm500592j_si_001.pdf (525.26 kB)
Energy Transfer from a Cationic Conjugated Polyelectrolyte to a DNA Photonic Wire: Toward Label-Free, Sequence-Specific DNA Sensing
journal contribution
posted on 2014-05-13, 00:00 authored by Zhongwei Liu, Hsing-Lin Wang, Mircea CotletWe demonstrate a label-free, sequence
specific DNA sensor based
on fluorescence resonant energy transfer (FRET) occurring between
a cationic conjugated polyelectrolyte and a small intercalating dye,
malachite green chloride. The sensor combines (1) conjugated polymer
chain conformation changes induced by the binding with DNA, with the
conjugated polymer wrapping/twisting around the DNA helical duplex
and experiencing a 3-fold increase in its photoluminescence quantum
yield and (2) FRET from the conjugated polymer to the intercalated
DNA. Owing to its small size, the dye intercalates at maximal, one-to-one
dye-to-base pair load, making the intercalated DNA a molecular photonic
wire with dyes excitonically coupled and chiroptically active. Any
sequence mismatch between probe and target DNA degrades the intercalated
DNA photonic wire by decreasing its brightness, excitonic coupling,
and chiroptical properties, and this provides a signal transduction
method for the DNA sensor. Coupling of intercalated DNA with the conjugated
polymer via FRET provides target signal amplification and increased
sensitivity toward sequence mismatch, with the FRET efficiency decreasing
with added DNA sequence mismatch.