| Because of its unique fluorescence characteristics,rare earth doped nanoparticles have wide application prospects in biomedicine and other fields.When rare earth materials are used as fluorescent probes,they interact with proteins and DNA and other macromolecules,which may affect the structure and function of these macromolecules and affect physiological functions.Therefore,it is important to study the interaction between rare earth nanocrystals and protein to evaluate the safety of rare-earth nanocrystals.In addition,the printing and dyeing wastewater contains some carcinogenic aromatic compounds such as acid fuchsin,which may pollute human drinking water.Therefore,it is of certain practical significance to develop a high sensitive,simple and rapid acid fuchsin detection method for environmental protection and human health.The main contents of this paper are as follows:1)hydrothermal synthesis of LaPO4:Eu fluorescent nanocrystals with a diameter of10nm on the surface.In the experiment,Fu Liye transform infrared spectroscopy?FT-IR?,X ray diffraction?XRD?and transmission electron microscopy?TEM?were used to characterize the morphology and structure.At the same time,the optical properties were analyzed by fluorescence spectra and UV-vis absorption spectroscopy,and the effects of temperature,pH value and doping ratio on the luminescence properties of nanocrystalline were also examined.The physiological conditions were simulated and the interactions between LaPO4:Eu nanocrystals and HSA were analyzed using fluorescence?FL?and Raman spectroscopy methods.The spectral data of HSA-LaPO4:Eu system measured at 294,302and 310 K temperatures are deduced to be that the fluorescence quenching mechanism of HSA is dynamic quenching.At the same time,the number of binding sites of the system at three temperatures is equal to about 1,and the apparent binding constant Ka is5.944×103,3.041×103 and 2.890×103 L/mol.The thermodynamic parameters calculated from the Van't Hoff equation indicate that the binding reaction between nanocrystalline and protein is spontaneous,and the interaction force are mainly van der Waals forces or hydrogen bonds.The binding distance between them is 4.2 nm.The substitution results indicate that nanocrystals are mainly combined with Site I site of HSA molecules.The analysis of synchronous fluorescence,circular dichroism,three-dimensional fluorescence and FT-IR spectra showed that the addition of LaPO4:Eu did not induce the conformation changes of HSA molecules.2)Hydrothermal synthesis of spherical NaYF4:Yb,Er coated with oleic acid with a particle size of about 10 nm,and Er up conversion fluorescence nanocrystals.In the experiment,the morphology and structure of NaYF4:Yb,Er were characterized by FT-IR,XRD and TEM,and the optical properties of the nanocrystalline were analyzed by state steady fluorescence and UV-vis absorption spectroscopy.Based on the synthesized upconversion nanocrystals as probes,a new method for quantitative analysis of acid fuchsin is established based on the internal filtration effect.The incubation time and pH of rare earth nanocrystals were optimized.Under the optimum conditions,the concentration of acid fuchsin in the range of 13.3×10-566.7×10-55 mol/L has a good linear relationship with the descrease in the fluorescence intensity of NaYF4:Yb,Er.The corresponding linear fitting equation is?F=2.75C+5.33,the relative standard deviation are 1.6×10-5mol/L?S/N=3?and 3.6%.The established method is applied to the determination of real samples with the recovery rate ranging from 96%to 104%.Besides,the interference experiments indicated that common substances have no significant effects on the detection of acid fuchsin,which shows that this method has good selectivity. |
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