Research On The Dual-signal Ratio Probe Based On The Novel Nanocomposite And Its Fluorescence Color Difference Visualization And Quantitative Detection

As one type of the most widely studied and applied fluorescent materials,fluorescent nanomaterials have various preparation methods,facile conditions,superior luminescence properties and low toxicity.Since its first discovery,carbon quantum dots or carbon dots have been widely used in medical imaging,biochemical sensing,environmental monitoring,energy development and other important fields.Silver nanoclusters have many advantages,such as good water-solubility,small particle sizes,high biocompatibility,easy of conjugation with biomolecules and so on,which show numerous applications in the fields of biosensors,cell imaging,nano-medicine and so on.In this paper,two novel nanocomposite fluorescent materials were designed and constructed towards dual-signal ratiometric fluorescent probe systems,which can be used for quantitative detection of biological or drug molecules based on fluorescence spectra and fluorescence chromatism.Typically,the main research contents are available as follows:One:Based on the use of dual-emissive CDs and citric acid-stablized AgNPs,a dual-signal ratiometric nanoprobe was prepared for the detection of cymoxanil?CYM?.Under excitation at 350 nm,CDs showed blue-green fluorescence with emission centers at 435 nm and 520nm,respectively.When CDs and AgNPs were mixed in water dispersion,the blue fluorescence intensity of CDs decreased due to fluorescence internal filtration effect?IFE?.When CYM was added into the mixture,the agglomerations of AgNPs were initiated.The agglomerated AgNPs were orange.The maximum absorption wavelength of the agglomerated AgNPs was shifted to 510 nm,and the absorption spectrum overlapped with the emission spectrum of CDs at 520 nm.The green fluorescence of CDs was quenched by IFE,and blue fluorescence of CDs was recovered gradually.Based on the nanocomposites constructed by CDs and AgNPs,a dual-signal ratiometric probe was constructed and was then applied to ratiometric colorimetry of CYM,ratiometric fluorescence spectrum and fluorescence color-difference visual quantitative detection of CYM in aqueous solution and on filter paper.Two:By means of BPQDs-doped MOF and AgNCs,a functionalized enzyme-catalyzed bioprobe was designed.Under excitation at 440 nm,AgNCs/BPQDs/MOF nanocomposites exhibited red-blue dual-emissive fluorescence at 630 nm and 535 nm.Baicalin can enhance the bioactivity of catalase and promote the decomposition of H₂O₂.In the mixed solution of nanocomposites,catalase and H₂O₂,with the increased concentration of baicalin,the activity of catalase increased,which led to the acceleration of H₂O₂ decomposition and the consumption of more H₂O₂.The red fluorescence of AgNCs on MOF surface was gradually enhanced,which served as a response signal.The blue fluorescence of BPQDs doped into the microstructure of MOF was much weak,which served as a reference signal.Based on AgNCs/BPQDs/MOF nanocomposites,thus an enzyme-catalyzed dual-signal ratiometric probe was constructed.The probe showed high sensitivity,selectivity and stability for the determination of Baicalin in practical samples.The probe was used for fluorescence chromatism visual quantitative detection of Baicalin in aqueous solutions,on filter strips and flexible films.