Experimental and computational investigation of a DNA-shielded 3D metal–organic framework for the prompt dual sensing of Ag+ and S2−

We herein report an efficient Ag+ and S2− dual sensing scenario by a three-dimensional (3D) Cu-based metal–organic framework [Cu(Cdcbp)(bpea)]n (MOF 1, H3CdcbpBr = 3-carboxyl-(3,5-dicarboxybenzyl)-pyridinium bromide, bpea = 1,2-di(4-pyridinyl)ethane) shielded with a 5-carboxytetramethylrhodamine (TAMRA)-labeled C-rich single-stranded DNA (ss-probe DNA, P-DNA) as a fluorescent probe. The formed MOF-DNA probe, denoted as P-DNA@1, is able to sequentially detect Ag+ and S2− in one pot, with detection limits of 3.8 nM (for Ag+) and 5.5 nM (for S2−), which are much more lower than the allowable Ag+ (0.5 μM) and S2− (0.6 μM) concentration in drinking water as regulated by World Health Organization (WHO). The detection method has been successfully applied to sense Ag+ and S2− in domestic, lake, and mineral water with satisfactory recoveries ranging from 98.2 to 107.3%. The detection mechanism was further confirmed by molecular simulation studies.