A Eu(III) doped metal-organic framework conjugated with fluorescein-labeled single-stranded DNA for detection of Cu(II) and sulfide.

In this paper, Bio-MOF-1 is prepared as reported and then Eu3+ is introduced into it via cation exchange method. A FAM-labeled ssDNA is chosen to fabricate with the obtained Eu3+@Bio-MOF-1. A luminescent hybrid material is assembled, which can exhibit the fluorescence of Eu3+ and FAM simultaneously by adjusting the ratio of FAM-ssDNA and Eu3+@Bio-MOF-1. The sample is then used for the detecting of metal ions, results shows which has good selectively for Cu2+ (LOD = 0.14 μM, 0-250 μM). The introduction of Cu2+ can quench the fluorescence of FAM while the luminescent intensity of Eu3+ enhancing. After the detection of Cu2+, the Cu2+ involved hybrid system can then be further employed for the detection of S2- (LOD = 1.3 μM, 0-50 μM). Low concentration of S2- can make the luminescent intensity of Eu3+ decrease gradually while high concentration of S2- can further recover the luminescent of FAM, which is quenched by Cu2+.