Research On Ratio Fluorescence Probe Based On Copper Clusters And Carbon Dots And Its Visual Detection Application

Metal nanoclusters?MNCs?consist of several to tens of atoms and have caused considerable research enthusiasm due to their unique electrical,physical and optical properties.When compared with the extensive studies of gold nanoclusters and silver nanoclusters,the application of copper clusters is relatively limited.So far,the research progress of copper clusters is still in the early stage.Carbon dots?CDs?are receiving an increasing attention due to their significant advantages,such as low toxicity,chemical inertness,phototunability,good water solubility and physicochemical properties.Due to these excellent properties of carbon dots,they have been used in many fields,including chemical and biological sensing,fluorescence imaging,drug delivery,etc.According to the excellent physicochemical properties of copper clusters and carbon dots,this dissertation designed two novel ratiometric fluorescent probe detection systems based on copper clusters and carbon dots,and applied them to the study of biomolecules,as follows:?1?Based on the hydrothermal method,copper clusters?CuNCs?were prepared by using N₂H₄·H₂O as a reducing agent and lysozyme as a stabilizer.The prepared CuNCs exhibited blue-light emission with a peak of 440 nm in the center of luminescence.In a mixture system consisting of CuNCs,choline oxidase,horseradish peroxidase?HRP?and o-phenylenediamine?OPD?,the added choline was catalyzed by choline oxidase to produce H₂O₂.OPD was oxidized by H₂O₂ and HRP to produce 2,3-diaminophenazine?DAP?.As an oxidation product of OPD,the fluorescence emitted by DAP peaks at 550nm,and the fluorescence exhibited a regular increase as the concentration of choline increased.At the same time,the fluorescence of CuNCs was attenuated by DAP absorption due to fluorescence quenching induced by internal filtration effects.?2?A dual-emitting fluorescent probe was designed based on carbon dots and copper nanoclusters.Firstly,carbon dots were prepared by hydrothermal method,and then copper nanoclusters with red fluorescence were prepared based on DNA template method,using single-stranded DNA as template.The carbon dots combined with copper nanoclusters by electrostatic bonding to form a dual-emitting fluorescent probe.Static quenching of fluorescence carbon dots was due to the combination of arginine and carbon dots.Acetaminophen was added to the composite system containing arginine-carbon dot/DNA-copper nanocluster?Arg-CDs/DNA-CuNCs?.Due to the interactions between arginine and acetaminophen,the combination of arginine and acetaminophen made the fluorescence of carbon dots restored.In this system,the copper nanocluster provided a reference signal to detect changes of the concentration of acetaminophen in the system,based on the ratio of fluorescence intensities of carbon dots and copper clusters.A ratiometric fluorescence detection platform was fabricated for acetaminophen detection.According to the experimental results,the CDs/DNA-CuNCs dual-emission ratiometric fluorescence platform had high sensitivity and accuracy for acetaminophen detection.