Fluorescence detection of Pb(2+) based on the DNA sequence functionalized CdS quantum dots.

In this paper, we have developed a simple and rapid method for the detection of Pb(2+) based on the DNA sequence capped CdS quantum dots (QDs). We utilized the designed guanine (G)-rich DNA sequence (PS2.M) as a coating reagent to synthesize the DNA-capped CdS QDs. The designed G-rich DNA sequence PS2.M can bind with hemin to form G-quadruplex/hemin complex with K(+), accompanied by the fluorescence quenching of CdS QDs via the photoinduced electron transfer. Pb(2+) can induce conformational changes in the G-quadruplex/hemin complex to release the hemin molecules, so the quenched fluorescence of CdS QDs could be recovered. Therefore, the new fluorescent analysis system could be applied for the detection of Pb(2+) based on the label-free DNA sequence capped CdS QDs.