FRET acceptor suppressed single-particle photobleaching in semiconductor polymer dots

Brightness and photostability are key parameters for fluorescent probes in optical imaging. This Letter describes Förster resonance energy transfer (FRET) as a useful strategy to enhance the photostability of fluorescent nanoparticles. Small molecules as FRET acceptors were doped into semiconductor polymer dots (Pdots), yielding apparent suppression of their rapid photobleaching in single-particle imaging. For 20 nm-diameter particles, the photobleaching percentage decreased from 71.8% to 47.2% after dye doping, while the single-particle brightness remained unchanged. The photostability of large Pdots was also enhanced by FRET at the expense of a moderate decrease in per-particle brightness as compared to the pure Pdots. This study indicates that FRET is a facile, yet effective, approach to mediate the brightness and photostability of fluorescent nanoparticles. Considering the combined factors of brightness and photostability, the dye-doped Pdots of ∼20  nm diameter are the most suitable for long-term imaging and tracking applications.