A novel upconversion luminescence turn-on nanosensor for ratiometric detection of organophosphorus pesticides

In this paper, an upconversion luminescence (UCL) “turn-on” nanosensor based on Tween-20 modified blue-emissive upconversion nanoparticles (UCNPs) has been fabricated for the ratiometric detection of organophosphorus (OP) pesticides. Due to the existence of a luminescence resonance energy transfer (LRET) effect between UCNPs and the pesticide probe (abbreviated as HODN), blue emission at 475 nm of UCNPs was quenched. Interestingly, upon the addition of the pesticide mimic diethyl chlorophosphate (DCP) or the OP pesticide dimethoate, UV absorption of HODN at 475 nm gradually vanished, and the LRET effect was suspended. Consequently, the blue UCL of UCNPs can be recovered well within a very short interval. Since the UCL emission at 803 nm was impervious to the interaction between HODN and pesticides, it can act as an internal standard for the accurate detection of pesticides. Additionally, it was demonstrated that HODN could quantitatively detect dimethoate in the range of 0–80 μM. Importantly, this nanosensor is qualified for the detection of pesticides in pure aqueous solution. Compared with enzymatic and electrochemical based detection methods for OP pesticides, this strategy was much more convenient and economical.