In this paper

a fluorescent probe for the dectection of cimetidine was fabricated based on fluorescence resonance energy transfer effect(FRET) between carambola carbon quantum dots(CB-CQDs) and silver nanoparticles(AgNPs).The CB-CQDs with high fluorescence intensity and good luminescence performance were synthesized by hydrothermal method using natural fruit carambola as the only raw material

which morphology and properties were characterized by ultraviolet-visible spectroscopy(UV-Vis)

infrared spectroscopy(FTIR)

transmission electron microscopy(TEM) and fluorescence spectrometry(FL)

respectively.It was found that

when AgNPs was added into a pH 6.0 Britton-Robinson buffer solution containing CB-CQDs，the fluorescence signal of CB-CQDs at λex/λem=319 nm/397 nm was gradually quenched through the FRET effect

in which CB-CQDs and AgNPs acted as fluorescence donor and fluorescence acceptor

respectively.While in the presence of cimetidine

the fluorescence signal of CB-CQDs was restored and fluorescence signal “turned on” again

forming an “off-on” cimetidine sensor

and the basic mechanism was further discussed.Under the optimized conditions

there was a good linear relationship between fluorescence recovery value(ΔIF) and cimetidine concentration in the range of 9.0×10-8-1.0×10-6 mol/L

with a correlation coefficient(r) of 0.998 6.The detection limit was calculated to be 1.9×10-8 mol/L based on the 3σ/k principle.This method was successfully applied to the detection of cimetidine in real samples with satisfactory results.