A new ratiometric fluorescence nanosensor based on NaYF4:3%Er@NaYF4 upconversion nanoparticles for sensitive determination of Rose Bengal in water.

Rose Bengal (RB) is used as a sensitizer in ambient water due to its property of catalyzing the production of singlet oxygen (1O2). However, this property also brings phototoxicity and carcinogenicity. The NaYF4:3%Er@NaYF4 core-shell upconversion nanoparticles (UCNPs) with higher upconversion efficiency was synthesized to detect RB in ambient water. Due to fluorescence resonance energy transfer (FRET) between RB and UCNPs, the upconversion fluorescence at 538 nm emitted by UCNPs was quenched by the RB, while the emission at 566 nm of RB raised. In the best conditions, the ratiometric emission intensity F566/F538 was positively proportional to RB concentration and the linear range was 0.04-15.0 μg·mL-1 (R2 = 0.996). The detection limit (S/N = 3) of RB was 2.46 ng·mL-1. The recoveries ranged from 99.0% to 105.6% (relative standard deviation 0.97-3.24%, n = 3) in tap water and 100.3%-104.9% (relative standard deviation 0.66-1.94%, n = 3) in lake water. This proposed method exhibits lower detection limit and larger linear, which possesses practical application value to the detection of RB in water.