Preparation And Application Of Ratiometric Fluorescent Probe Based On Fluorescent Nanomaterials And Molecular Imprinting Technology

The ratiometric fluorescent probe is generally prepared by combining two fluorescent materials with different emission wavelengths,and then the ratio of the fluorescence intensity of the two emission peaks is measured under the same wavelength excitation as the signal parameter to realize the analysis and detection of the target.The preparation of ratiometric fluorescent probes with superior performance is one of the current research hotspots in the analytical field.It is difficult to prepare a ratiometric fluorescent probe with high selectivity if the two fluorescent materials are simply combined.However,the combination of fluorescent materials and molecularly imprinted technique can enhance the selective recognition ability of the probe and obtain a molecularly imprinted ratiometric fluorescent probe with excellent performance.In this paper,the four kinds of molecularly imprinted ratiometric fluorescent probes were constructed based on the fluorescence properties of Schiff-base fluorescent compounds,quantum dots,luminescent metal organic frameworks,and the selective recognition ability of molecularly imprinted technique for fluorescent analysis and visual detection of impurities in traditional Chinese medicine and environmental samples.The main content of the paper is as follows:(1)A novel molecularly imprinted ratiometric fluorescent probe(MIRF probe)for the visual detection of aristolochic acid I(AA?)was constructed.The probe was prepared by using the Schiff-base fluorescent compound N,N'-bis(o-carboxybenzylidene)-p-4,4'-diaminobiphenyl(BDDB),which could emit blue fluorescence,as the reference signal material,and the carbon quantum dots carbon dots(y-CDs),which could emit yellow fluorescence,as the response signal material,combined with molecularly imprinted technology.The probe emits two independent fluorescence peaks at 440 nm and 530 nm under?_ex=365 nm.After adding AA?,the fluorescence intensity at 530 nm will be quenched,while the fluorescence intensity at 440 nm remains constant.Under the optimal experimental conditions,the linear range of this method is1.0?120.0?M,the limit of detection is 0.45?M(3?/s),and the fluorescent color of MIRF probe changes gradually from yellow to green to blue.The probe had been successfully applied to the detection of toxic impurity AA? in Asarum.The results show that this method has good selectivity,high sensitivity and significant visual detection effect for AA?,which provides a new method for the detection of AA?.(2)A molecularly imprinted ratiometric fluorescent test strip for the visual detection of pesticide residue pentachloronitrobenzene(PCNB)was prepared.A reference signal material emitting green fluorescence and a response signal material emitting orange fluorescence were synthesized by using a multicolor emission Schiff-base fluorescent compound1,1'-{4,4'-Biphenyldiylbis[nitrilo(E)methylylidene]}di(2-naphthol)(BPDN)as fluorescence material,respectively.Then the molecularly imprinted ratiometric fluorescent probe was prepared by combining with molecularly imprinted technology,and the probe was adsorbed on the filter paper to obtain a molecularly imprinted ratiometric fluorescent test strip.The probe emits two independent fluorescence peaks at 440 nm and 516 nm under?_ex=365 nm.After PCNB is added,the fluorescence intensity at 516 nm will be quenched,while the fluorescence intensity at 440 nm remains constant.Under the optimal experimental conditions,the linear range is 50.0?600.0?M,the limit of detection is 14.7?M(3?/s),and the fluorescent color of the probe changes gradually from orange to yellow to green.The results show that this method has good selectivity,high sensitivity and remarkable visual detection effect.The probe had been successfully applied to the detection of PCNB in tap water,soil and Arillus Longanae samples,and the prepared test strip had also been successfully used for the visual detection of PCNB.(3)A molecularly imprinted ratiometric fluorescent probe for the visual detection of pesticide residue chlorpropham(CIPC)was constructed.Blue fluorescent carbon quantum dots were synthesized by a solvothermal method using sodium citrate as carbon source.On this basis,a molecularly imprinted polymer for recognizing CIPC was prepared by a precipitation polymerization method with carbon quantum dots emitting blue fluorescence as fluorescence response signal material,and then the internal standard silica(BPDN@SiO₂)emitting orange fluorescence was added to construct the molecularly imprinted ratiometric fluorescent probe.The probe emits two independent fluorescence emission peaks at 470 nm and 560 nm under?_ex=365 nm.After CIPC is added,the fluorescence intensity at 470 nm will be quenched,while the fluorescence intensity at 560 nm remains constant.Under the optimal experimental conditions,the linear range of this method is 10.0?70.0?M,the limit of detection is 2.89?M(3?/s),and the fluorescent color of the probe changes gradually from blue to green and then to yellow and finally becomes Orange.Furthermore,the probe had been successfully applied to the detection of CIPC in tap water,soil and Arillus Longanae samples with satisfactory results.(4)A molecularly imprinted ratiometric fluorescent probe for the visual detection of pesticide residue dinotefuran was constructed.Firstly,a calcium based luminescent metal organic framework was synthesized by a solvothermal method.In order to enhance its selectivity,a molecularly imprinted polymer for recognizing dinotefuran was prepared by a precipitation polymerization method using dinotefuran as template molecule,methacrylic acid and acrylamide as bifunctional monomers,and then the internal standard silica(CdTe@SiO₂)emitting red fluorescence was added to construct the molecularly imprinted ratiometric fluorescent probe.The probe emits two independent fluorescence emission peaks at 500 nm and 560 nm under?_ex=400 nm.After dinotefuran is added,the fluorescence intensity at 500 nm will be quenched,while the fluorescence intensity at 560 nm remains constant.Under the optimal experimental conditions,the linear range is 12.0?84.0?M,the limit of detection is 3.36?M(3?/s),and the fluorescent color of the probe changes gradually from green to yellow and finally turns to red.Furthermore,the probe had been successfully applied to the detection of dinotefuran in tap water,soil and Arillus Longanae samples with satisfactory results.