Construction Of Fluorescence Sensor P-DNA@MOF For The Sequential Detection Of Ag⁺ And S^2-

Silver ion?Ag? is ubiquitous and widely applied in various fields including biomedicine,antibacterial manufacturing,and etc.However,the biological accumulation of Ag⁺ raises serious concerns as a result of its relevance to multiple organ dysfunction syndrome,cytotoxicity,argyria and weakness of mitochondrial ability.On the other hand,sulfur ion?S2-?with rich biological functions,is widely used in various industries.High concentrations of S2-increase the risk of diabetes,cirrhosis,alzheimer's and down syndrome in our bodies.H2S formed by S2-and H+ is closely related to human atherosclerosis,hypertension,liver cirrhosis and heart failure.Moreover,S2-can combine with Ag⁺ to form Ag2S,which can stimulate the human skin and the mucous membrane of digestive system,respiratory system,excretory system and reproductive system.Therefore,the construction of an efficient and sensitive sensing platform for the specific detection of Ag⁺ and S2-has important significance for the protection of the ecological environment and detection of related diseases.Metal Organic Framework?MOF?,is a new type of organic-inorganic hybrid materials formed by organic ligand and metal ion through self-coordination which is powerful as fluorescent sensors for the detection of mental ions and small biomolecules.However,the employ of MOF for detecting heavy metal ions based on metal ion specific DNA?Probe DNA,P-DNA?is still in its infancy.Up to now,it has not been reported that MOF hybridized with P-DNA to establish a fluorescence sensor for the detection of Ag⁺ or the sequential detection of Ag⁺ and S2-.Based on the above research background,we have constructed a three-dimensional?3D?Cu-based MOF[Cu?Cdcbp??bpea?]n?MOF 1,H3CdcbpBr =3-carboxyl-?3,5-dicarboxybenzyl?-pyridinium bromide,bpea= l,2-di?4-pyridinyl?ethane?from the reaction of Cu???with a quaternized tricarboxylic acid ligand.In MOF 1,the Cdcbp and bpea ligands contain conjugated ?-electron system,Cu²⁺,and quaternary ammonium groups,all facilitate its binding with a single-stranded,carboxytetramethylrhodamine?TAMRA?-labeled C-rich P-DNA to form P-DNA@1 system through ?-? interactions and hydrogen bonding,and ultimately led to fluorescence quenching with quenching efficiency of 89.3%.Then Ag⁺ was added,the fluorescence of P-DNA@1 probe recovered with the recovery efficiency being 4.9 forming ds-DNA@Ag⁺ systerm for S2-detection.The fluorescence sensing system is not affected by physiological pH and other metal ions and small anions in solution.The detection limits of Ag⁺ and S2-were 3.8 nm and 5.5 nm respectively and the fluorescence intensity of the system had a good linear relationship with the concentrations of Ag⁺ and S2-the correlation coefficient R2= 0.9995 and 0.9978,respectively.It also obtained satisfactory recovery rate?98.20?107.30%?in the detection of Ag⁺ and S2-in environmental water samples.The detection mechanism was also described by circular dichroism,fluorescence anisotropy experiment and computer simulation.