Fluorescence quenching of quantum dots by gold nanoparticles: a potential long range spectroscopic ruler.

The dependence of quantum dot (QD) fluorescence emission on the proximity of 30 nm gold nanoparticles (AuNPs) was studied with controlled interparticle distances ranging from 15 to 70 nm. This was achieved by coassembling DNA-conjugated QDs and AuNPs in a 1:1 ratio at precise positions on a triangular-shaped DNA origami platform. A profound, long-range quenching of the photoluminescence intensity of the QDs was observed. A combination of static and time-resolved fluorescence measurements suggests that the quenching is due to an increase in the nonradiative decay rate of QD emission. Unlike FRET, the energy transfer is inversely proportional to the 2.7th power of the distance between nanoparticles with half quenching at ∼28 nm. This long-range quenching phenomena may be useful for developing extended spectroscopic rulers in the future.