The Construction Of Nano-luminescent Material YPO₄:Sm³⁺@YPO₄@PEG And Its Interaction With Protein

Proteins,nucleic acids and carbohydrates are the main components in biological systems,and exploring the interaction between proteins and fluorescent molecules is an indispensable direction in the field of biomedicine.Therefore,the research and development of nano-fluorescent materials with potential application value.In order to change the hydrophobicity and fluorescence properties of rare earth luminescent materials,a bilayer fluorescent nanomaterial:YPO₄:Sm³⁺@YPO₄@PEG was constructed by hydrothermal and microwave methods in this work.Firstly,the core/shell nanoluminescent materials YPO₄:Sm³⁺@YPO₄with different"core diameter:shell thickness"were prepared by adjusting different core/shell molar ratios,and the optimal molar ratio that could enhance the fluorescence properties of the host nanomaterials was selected.Then,0.2 g of PEG was selected for coating to obtain a double-layer fluorescent nanomaterial YPO₄:Sm³⁺@YPO₄@PEG.The structure,morphology and fluorescence properties of the products were characterized by XRD,SEM,TEM,IR and FL.The results show that nano-spherical,with a radius of 60-100 nm and a coating thickness of 10-20 nm.The fluorescence intensity of double-layer core/shell structure YPO₄:Sm³⁺@YPO₄@PEG is more than 6 times enhanced than that of nano-phosphor YPO₄:Sm³⁺.It can be seen that the double-layer fluorescent nanomaterial is not only hydrophilic and biocompatible,but also enhances the fluorescence intensity of YPO₄:Sm³⁺.At room temperature,the calibration of bovine serum albumin（BSA）and human serum albumin（HSA）by YPO₄:Sm³⁺@YPO₄@PEG was investigated by fluorescence spectroscopy,and the corresponding fluorescence spectra and linear fitting formula were obtained.The in vitro interactions of YPO₄:Sm³⁺@YPO₄@PEG with BSA and HSA were studied by fluorescence and absorption spectroscopy.The fluorescence of both bovine and human serum albumin was quenched by YPO₄:Sm³⁺@YPO₄@PEG at different measurement temperatures.The mechanism of fluorescence quenching is static quenching of complex formation.The binding distances of BSA—YPO₄:Sm³⁺@YPO₄@PEG and HSA—YPO₄:Sm³⁺@YPO₄@PEG were both less than 8 nm,indicating that energy transferred from serum albumin to the nano-fluorescent material YPO₄:Sm³⁺@YPO₄@PEG have occurred.Judging from the study of thermodynamic parameters and forces,the reaction type of the fluorescent complex is a spontaneous exothermic reaction,and the enthalpy change（ΔH）and entropy change（ΔS）of the interaction of YPO₄:Sm³⁺@YPO₄@PEG with BSA and HSA at different temperatures are all less than 0,indicating that the interaction of YPO₄:Sm³⁺@YPO₄@PEG with BSA and HSA is mainly driven by van der Waals forces and hydrogen bonding.Finally,the effect of YPO₄:Sm³⁺@YPO₄@PEG on protein conformation was investigated by synchronous fluorescence spectroscopy and three-dimensional fluorescence spectroscopy.YPO₄:Sm³⁺@YPO₄@PEG binds to bovine and human serum albumin near the tyrosine residue,and the hydrophobicity of the environment in which the tyrosine amino acid is located increases,causing its structure to change.The results show that the binding of YPO₄:Sm³⁺@YPO₄@PEG to the protein can cause the conformational changes of bovine and human serum albumin.