| Autor: |
Huang NH; Guangdong Provincial Key Laboratory of New Drug Screening, School of Pharmaceutical Sciences, Southern Medical University, Guangzhou 510515, China. jxchen@smu.edu.cn., Liu Y, Li RT, Chen J, Hu PP, Young DJ, Chen JX, Zhang WH |
| Abstrakt: |
Zwitterionic metal-organic frameworks (MOFs) of {[Cu(Cbdcp)(Dps)(H 2 O) 3 ]·6H 2 O} n (MOF 1) and [Cu 4 (Dcbb) 4 (Dps) 2 (H 2 O) 2 ] n (MOF 2) (H 3 CbdcpBr = N-(4-carboxybenzyl)-(3,5-dicarboxyl)pyridinium bromide; H 2 DcbbBr = 1-(3,5-dicarboxybenzyl)-4,4'-bipyridinium bromide; Dps = 4,4'-dipyridyl sulfide) quench the fluorescence of cytosine-rich DNA tagged with 5-carboxytetramethylrhodamine (TAMRA, emission at 582 nm, denoted as C-rich P-DNA-1) and yield the corresponding P-DNA-1@MOF hybrids. Exposure of these hybrids to Ag + results in the release of the P-DNA-1 strands from the MOF surfaces as double-stranded, hairpin-like C-Ag I -C (ds-DNA-1@Ag + ) with the restoration of TAMRA fluorescence. The ds-DNA-1@Ag + formed on the surface of 1 can subsequently sense biothiols cysteine (Cys), glutathione (GSH), and homocysteine (Hcy) due to the stronger affinity of mercapto groups for Ag + that serves to unfold the ds-DNA-1@Ag + duplex, reforming P-DNA-1, which is re-adsorbed by MOF 1 accompanied by quenching of TAMRA emission. Meanwhile, MOF 2 is also capable of co-loading a thymine-rich probe DNA tagged with 5-carboxyfluorescein (FAM, emission at 518 nm, denoted as T-rich P-DNA-2) to achieve synchronous sensing of Ag + and Hg 2+ , resulting from the simultaneous yet specific ds-DNA-1@Ag + and T-Hg II -T duplex (ds-DNA-2@Hg 2+ ) formation, as well as the distinctive emission wavelengths of TAMRA and FAM. Detection limits are as low as 5.3 nM (Ag + ), 14.2 nM (Cys), 13.5 nM (GSH), and 9.1 nM (Hcy) for MOF 1, and 7.5 nM (Ag + ) and 2.6 nM (Hg 2+ ) for MOF 2, respectively. The sequential sensing of Ag + and biothiols by MOF 1, and the synchronous sensing of Ag + and Hg 2+ by MOF 2 are rapid and specific, even in the presence of other mono- and divalent metal cations or other biothiols at much higher concentrations. Molecular simulation studies provide insights regarding the molecular interactions that underpin these sensing processes. |
