Fluorescence Analysis Method Based On Lead Halide Perovskite Nanoparticles

Lead halide perovskite nanoparticles(ABX3,A=MA,FA,Cs,B=Pb,X=Cl,Br,I,Cl/Br,Br/I)are a type of nanomaterials with a cubic structure,which have many excellent photophysical properties such as wide absorption spectrum,high photoluminescence quantum yield,narrow half-peak width and adjustable emission spectrum.Lead halide perovskite nanoparticles have been used to develop fluorescence methods to detection of Cu2+ in edible oil,organophosphorus pesticides in vegetables and soil samples.Most of these methods were based on direct inhibition of fluorescence of lead halide perovskite nanoparticles by the targets and performed in organic phase.It is necessary to develop a new sensing mode that can be used to detect analytes in the aqueous solution for expanding the application of lead halide perovskite nanoparticles in the field of analytical chemistry.In this thesis,lead halide perovskite nanoparticles with good-water solubility were successfully synthesized.A fluorescence analytical method was established by their well fluorescence properties with inner filter effect of gold nanoparticles(AuNPs)and manganese dioxide nanosheets(MnO2)of strong light absorption properties.The detailed contents are as follows.Part one.Perovskite nanoparticles fluorescence nanosensor for ultrasensitive detection of trace melamine in dairy products by the manipulation of gold nanoparticlesBarium sulfate-coated lead halide perovskite nanoparticles(CsPbBr3 NPs@BaSO4)was successfully synthesized that exhibited stable and intense fluorescence property in aqueous buffer.It was found that the citrate-stabilized gold nanoparticles have an absorption peak at 520 nm,meanwhile the CsPbBr3 NPs@BaSO4 have an emission at 520 nm.The fluorescence of the CsPbBr3 NPs@BaSO4 was obviously inhibited by the AuNPs due to inner filter effect.AuNPs were aggregated by the addition of melamine and the absorption spectrum of the agglomerated AuNPs did not overlap with the fluorescence emission spectrum of CsPbBr3 NPs@BaSO4,which caused a recovery in the fluorescence of the CsPbBr3 NPs@BaSO4.The recovery ratio of the CsPbBr3 NPs@BaSO4 fluorescence signal was proportional to the concentration of melamine in the range of-5.0-500.0 nmol/L.The limit of detection was 0.42 nmol/L and the relative standard deviation was 4.0%for the repetitive determination of 500.0 nmol/L melamine solution(n=11).The nanosensor was successfully applied to analysis of melamine in dairy product samples.Part two.Inhibitory fluorescence of lead halite perovskite nanoparticles for determination of sulfide ionsA fluorescence method was developed for the determination of sulfide ion with lead halide perovskite nanoparticles(CsPbBr3 NPs)as fluorescent probes.With the simple mixing of CsPbBr3 NPs and sulfide ion sulfide ion can intensely quench the fluorescence of CsPbBr3 NPs due to generating more stable precipitation of PbS perhaps.The fluorescence intensity of the CsPbBr3 NPs was gradually decreased with the increase of the concentration of sulfide ion.Based on these observations,a fluorescence method was developed for the detection of sulfide ions in water samples.The linear range for sulfide ions was 0.05-1.00 ?mol/L and the detection limit was 19.5 nmol/L.The method has good selectivity to sulfide ions and has been successfully used for determination of sulfide ion in water samples.Part three.Lead halide perovskite nanoparticles-based fluorescence detection of glutathione with inner filter effect of manganese dioxide nanosheetsIn this work,a fluorescence method for the detection of glutathione was established by using lead halide perovskite nanoparticles(CsPbCl3 NPs)as fluorescent signal units and MnO2 nanosheets as fluorescence quenchers.Lead halide perovskite nanoparticles were positively charged and MnO2 nanosheets were negatively charged.When they were mixed,CsPbCl3 NPs was adsorbed on the surface of MnO2 nanosheets by electrostatic interaction,the fluorescence of CsPbCl3 NPs was quenched by MnO2 nanosheets due to the inner filter effect.The fluorescence of CsPbCl3 NPs can be restored in the presense of glutathione,in which MnO2 nanosheets was reduced to Mn2+by glutathione and the inner filter effect of MnO2 decreased.The linear range for glutathione was 0.2-20.0 ?mol/L and the detection limit was 0.07 ?mol/L.The relative standard deviation was 3.5%for the 5.0 ?mol/L glutathione solution(n=11).In summary,fluorescence methods were constructed for the determination of small biomolecules by using the good optical properties of lead halide perovskite nanoparticles.The methods have the advantages of simple operation,low cost and high sensitivity,which has been successfully used for the determination of melamine and sulfide ion in actual samples.This work provides an idea for the application of lead halide perovskite nanoparticles in analytical chemistry and expands application range of lead halide perovskite nanoparticles in analytical chemistry.