Design and Synthesis of a β-Diketonate-Europium(Ⅲ)Complex-based Ratiometric Fluorescent Probe for Singlet Oxygen and Its Application in Cell Imaging
A ratiometric fluorescent probe([Eu(Hpfdap)3(CTMR-Phen-N)])was designed and synthesized for detection of singlet oxygen(1O2)with dimethyl anthracyl-containing β-diketone compound 1,1,1,2-pentafluoro-5-(9',10'-dimethyl-2'-anthracene)-3,5-pentanedione(Hpfdap)as recognition ligand and 5-amino-1,10-phenanthroline conjugated with Rhodamine as auxiliary ligand(CTMR-Phen-N).The results of spectral analysis showed that the europium(Ⅲ)complex had almost no fluorescence due to the presence of anthracene ring in the probe.After reaction with 1O2,the anthracene ring was oxidized to endoperoxide,and the fluorescence of the europium(Ⅲ)complex at 614 nm was restored,followed by the increase of quantum yield from 1.60%to 25.16%.The fluorescence intensity of Rhodamine at 575 nm remained unchanged before and after the reaction with 1O2.Therefore,the ratio of fluorescence intensity at 614 nm and 575 nm could be used to measure 1O2 by the developed rationmetric fluorescence method.The probe showed good selectivity for 1O2,and the detection limit(S/N=3)was as low as 3 μmol/L.The fluorescence imaging results demonstrated that the probe had low cytotoxicity and good membrane permeability,and could be applied to fluorescence imaging of 1O2 in Hela cells.