Successive and Specific Detection of Hg²⁺ and I^– by a DNA@MOF Biosensor: Experimental and Simulation Studies

Abstract

A 2D metal-organic framework (MOF) of {[Cu(Dcbb)(Bpe)]·Cl} (1, HDcbbBr = 1-(3,5-dicarboxybenzyl)-4,4'-bipyridinium bromide, Bpe = trans-1,2-bis(4-pyridyl)ethylene)) has been prepared. MOF 1 associates with the thymine-rich (T-rich), single-stranded probe DNA (ss-DNA, denoted as P-DNA) labeled with fluorophore FAM (FAM = carboxyfluorescein) and quenches the FAM emission to give a nonemissive P-DNA@1 hybrid (off state). The P-DNA in the hybrid subsequently captures the Hg to give a rigid double-stranded DNA featuring T-Hg-T motif (ds-DNA@Hg) and detach from MOF 1, triggering the recovery of the FAM fluorescence (on state). Upon subsequent addition of I, Hg was further sequestrated from the ds-DNA@Hg duplex, driven by the stronger Hg-I coordination. The released P-DNA is resorbed by MOF 1 to regain the initial P-DNA@1 hybrid (off state). The P-DNA@1 sensor thus detects Hg and I sequentially via a fluorescence "off-on-off" mechanism. The sensor is highly selective and sensitive, yielding detection limits of 3.2 and 3.3 nM, respectively. The detection process was conformed by circular dichroism (CD) and the detection mechanism was verified by fluorescence anisotropy, binding constant, and simulation of the binding free energy at each stage.

HRP@ZIF-8/DNA Hybrids: Functionality Integration of ZIF-8 via Biomineralization and Surface Absorption

“…Monitoring Hg 2+ and phenol level in wastewaters is crucial for human health. Encouraged by the excellent fluorescence quenching ability of ZIF-8 (reported by Hu et al 37 ) and the high activity and stability of HRP@ZIF-8, a fluorescent and colorimetric sensing platform for Hg 2+ ion and phenol detection was prepared by a HRP@ZIF-8/DNA hybrid system. The fluorescent detection of Hg 2+ was designed as shown in Figure 6.…”

Recent advances in fluorescence sensors based on DNA–MOF hybrids

“…Schematic illustration of (a) Hg 2+ detection (reproduced from ref. with permission from Wiley), and (b) Hg 2+ and biological thiols detection (reproduced from ref. with permission from Elsevier) based on a DNA and MOF hybrid as fluorescence sensors…”

“…In 2019, the same group utilized a hybrid composed of 1D Cu‐based MOFs [Cu (Cdcbp)(H 2 O) 2 . 2H 2 O] and FAM‐labelled probe DNA to detect Hg 2+ and biological thiols (biothiols) . Biothiols, including cysteine (Cys), homocysteine (Hcy) and glutathione (GSH), all own a mercapto group, and have a strong affinity toward Hg 2+ .…”

Water-Stable Silver-Based Metal–Organic Frameworks of Quaternized Carboxylates and Their Antimicrobial Activity

“…In the past few years, we have developed an intense interest in MOFs constructed from quaternized carboxylate ligands due to their good water-dispersity and water-stability. These MOFs have shown promising properties in magnetic resonance imaging, and as probes for nucleic acids, − metal ion, , and other biologically relevant species . Herein, we extended our focus on the antibacterial activity of MOFs of quaternized carboxylate ligands by their assembly with Ag + ion.…”