Dye-sensitized upconversion nanoprobes with ultra-high signal-to-background ratio for visual and sensitive detection of nerve agent mimics.

An exciting upconversion nanoprobe conditioning strategy is proposed to improve the signal-to-background ratio (SBR) through a dye-sensitized strategy, in which the dye functions both as a recognition unit of the detection target and as a sensitizer to amplify the visible luminescence of the lanthanide-doped upconversion nanoparticles (UCNPs), instead of a quencher. The application of this dye-sensitized upconversion nanoprobe to the visual detection of nerve agent mimics diethoxy phosphatidylcholine (DCP) showed excellent detection performance, with up to 110-fold enhancement of the luminescence response of the probe in DCP solution and a detection limit as low as 2 nM. Finally, we performed visual detection of DCP solution and vapor by using test strips containing the probe. It is promising to apply the probe to monitor the leakage of DCP in the real environment.