Preparation Of Metal Organic Framework-coated Noble Metal Clusters And The Applications In Heavy Metal Ions Detection

As a new type of fluorescent nanoparticles,noble metal nanoclusters have the following advantages:unique electronic energy level structure,high fluorescence efficiency,excellent biocompatibility and large Stokes displacement.Because of the excellent properties of noble metal nanoclusters,they can be used as the fluorescent probes for biosensing and imaging.The metal-organic framework?MOF?has an infinite three-dimensional?3D?framework structure,inherent microporosity and high surface area,which facilitates the interaction between MOF and Au nanoclusters.Therefore,based on the special optical properties of AuNCs and the advantages of MOF,the ratio fluorescence nanosensor constructed by MOF-coated AuNCs and its detection of Hg²⁺were studied.The ECL behavior of MOF on AuNCs was also explored.The major contents of this paper are as follows:1.Preparation and Characterization of dual-emission fluorescent nano-composites AuNCs/MOF/Cys.MIL-68?In?-NH₂ with blue fluorescence was combined glutathione-stabilized Au clusters?GSH-AuNCs?with red fluorescence to form the dual-emission fluorescent composite that produced light pink fluorescent emission.At the same time,the fluorescence intensity of GSH-AuNCs was significantly doubled.Cysteine?Cys?further enhanced the fluorescence emission of GSH-AuNCs at 668 nm and showed bright pink fluorescence.Meanwhile,the fluorescence intensity of GSH-AuNCs was significantly enhanced by 2.6 times.In addition,the prepared AuNCs/MIL-68?In?-NH₂/Cys nanocomposites still maintain the willow-like structure,and AuNCs still have good dispersibility.2.AuNCs/MOF/Cys fluorescence nanosensor for the detection of Hg²⁺.The ratiometric fluorescence nanosensor was constructed by nanocomposites,named as AuNCs/MIL-68?In?-NH₂/Cys.MOF has excellent surface area,porous structure and fluorescence characteristics.MOF was used as an internal standard and AuNCs were used as a response signal.In the presence of Hg²⁺,the red fluorescent peak at 668 nm was quenched,while the blue fluorescent peak at 438 nm unchanged.The sensor showed two linear ranges,20 pM?0.2?M and 0.2?M?60?M,with the detection limit of 6.7 pM and high selectivity for other ions.In addition,the microfluidic paper-based analysis device??PAD?was successfully fabricated as the simple and fast detection platform for the visual detection of Hg²⁺ranged from 5 nM to 50?M.3.Enhanced electrochemiluminescence of AuNCs/TPrA system by MOF.Using polyvinylpyrrolidone?PVP?as the stabilizer,the zeolitic imidazole ester framework material?ZIF-8?combined lipoic acid modulated Au nanoclusters?LA-AuNCs?to form AuNCs@ZIF-8.The structure of ZIF-8 could be changed by water.But the change does not affect its load AuNCs,LA-AuNCs still maintained its structure on ZIF-8,and had good dispersion.The ECL signal of the LA-AuNCs at the anode was effectively enhanced 3 fold in the tripropylamine?TPrA?solution,and the onset potential of the ECL was also advanced by0.06 V,and showed good stability.