by PhilipJ on 10 November 2005
In the most recent issue of Nature Materials, a Letter describing a new quantum dot(QD)-based DNA nanosensor is presented, a technique that is entirely different from traditional microarray chips.
Due to the unique properties of QDs (see this wikipedia entry), a group from Johns Hopkins has found a way to label individual quantum dots with many copies of a short probe strand of DNA. Upon binding a dye-labelled reporter strand of DNA, the quantum dot and dyed reporter strand act as an acceptor-donor pair for fluorescence resonsance energy transfer—FRET—based detection.
Without bound reporter strands, background noise is near-zero, while a detectable signal is seen for as few as 50 bound reporter molecules to a single QD. As a proof-of-concept, they also report on detection of a reporter molecule with a single point mutations, typical of some ovarian tumors.