Preparation Of Ternary Quantum Dots And Application In Fluorescent Biosensing Technology

The application based on ternary quantum dots?QDs?in biosensor has attracted wide interest due to their unique optical properties.Therefore,in this work,ternary quantum dots have been prepared as fluorophores and used in fluorescence biosensing technology and bioimaging for the detection of biomolecules.?1?Colloidal chemistry method is used to prepare a highly luminous water-soluble CdSexTe1-x quantum dots,where mercaptopropionic acid works as a stabilizer and dispersant.The effects of ratio of selenium and tellurium substances,ratio of Cd/MPA,and reaction time on the spectral properties of the ternary quantum dots are investigated.The results show that UV-visible absorption peak and fluorescence emission peak of the CdSe_xTe_1-x ternary quantum dot are changed with different proportions of Se and Te components.CdSe_0.5Te_0.5?CdSeTe?has the longest fluorescence emission wavelength,which can reach 662 nm and its fluorescence lifetime is 151.1 ns.The prepared ternary quantum dots have good dispersibility,narrow particle size distribution,and an average particle size of about3 nm.?2?A novel hierarchical AuNR@CdSeTe quantum dots core/shell structure has been fabricated using silicon isolation layer for biological application.AuNRs are coated with a dense layer of silica and mediated by an initial mesoporous silica layer,and then CdSeTe ternary quantum dot are directly assembled on the surface.The dense silica layer can reduce the potential fluorescence resonance energy transfer?FRET?between QDs and AuNRs.The molecular beacon?MB?-conjugated AuNR@CdSeTe fluorescent biosensors are prepared by nucleic acid hybridization technology in order to overcome the limitations of conventional bioprobes for Norovirus?NV?.The MB-conjugated AuNR@CdSeTe bioprobes have a good performance in the linearity,and the linear range of this assay is from 2 to 20copies/mL with a limit of detection?LOD?of 1.6 copies/mL.In addition,PEGylated AuNR@CdSeTe-SiO₂ nanoparticles have implemented in a dual-modal imaging with high contrasting fluorescence and dark field signals in cell imaging,which has a great potential in cancer diagnosis.?3?Because CdSeTe ternary quantum dots have high toxicity,the low toxicity CuInS₂/ZnS ternary quantum dots,which can have better application in the biological field,have been synthesized by the aqueous phase method.The effects of reaction temperature,pH value,reaction time,Cu/In ratio and other conditions on the optical properties of CuInS₂/ZnS ternary quantum dot are discussed,and the structure of the synthesized QDs is characterized.The CuInS₂/ZnS core/shell QDs with high luminescence,low toxicity,and good biocompatibility are used as a fluorophore and bound to dopamine?DA?through an amide bond.The dopamine-functionalized CuInS₂/ZnS ternary quantum dots have been utilized to detect Tau protein by tyrosinase?TYR?-induced fluorescence immunosensor technology.Tyrosinase?TYR?is conjugated with antiTau,and the CuInS₂/ZnS QDs-DA is added to the Tau aptamer-Tau-antiTau sandwich system where DA is catalyzed by TYR to cause fluorescence quenching in the presence of an analyte.And the fluorescence intensity of CuInS₂/ZnS-DA is related to the concentration of Tau protein.The detection concentration of Tau protein by this fluorescent immunosensor technology is from 10 pM to 200 nM with LOD of 9.3 pM.This work firstly supplies a fluorescence immunoassay by Tyrosinase-induced for the rapid detection of Tau protein,paving a new pathway for the detection of disease biomarkers.