Studies On Synthesis Of LaF₃: Ce, Tb/DPA-LaF₃:Tb Nanoparticles And Their Interactions With Bovine Serum Albumin

Duo to the special optical properties, many people pay attention to rare earthdoped luminescent nanoparticles. When rare earth nanoparticles as fluorescent probeare applied in the biomedical field, they could interact with protein and affect thestructure and function of protein and DNA. These may cause unknown physiologicaleffect. So the research of interactions between rare earth nanoparticles and proteinwill be very important on the development of biomedical and rare earthnanoparticles using security evaluation. In this paper, we sysnthesize two kinds ofrare earth doped nanoparticles and investigate their interactions with bovine serumalbumin with a variety of spectroscopy. The main contents as follows:1) LaF3:Ce,Tb nanoparticles which surface was coated by sodium citrate wassynthesized by hydrothermal method. The size was calculated to be about9.2nm.Fluorescence quantum yield was about3.3%. The spectroscopic properties ofprepared nanoparticles were studied by fluorescence spectra, ultraviolet absorptionspectrum, and the structures and morphology of them were characterized by FT-IRspectrascopy, X-ray diffraction and transmission electronic microscopy. Exploredthe influence of fluorescence spectroscopy by temperature and pH.Under the simulative physiology conditions, The interactions of LaF3:Ce,Tbnanoparticles with BSA had been detailedly studied by a variety of spectroscopictechnique such as fluorescence spectrum. The results that the fluorescence spectrumof BSA–LaF3:Ce,Tb system at290,300and310K showed that the quenchingmechanism of BSA fluorescence by LaF3:Ce,Tb nanoparticles was dynamicquenching. The binding sites n were about equal to1and the binding constants were1.411×104、4.606×103、1.497×103L·mol-1, respectively. According to the Van’t Hoffequation, the thermodynamic parameters were estimated, which indicated thatnanoparticles interacted with BSA mainly through hydrophobic forces and thiscombining process is a spontaneous procedure. According to the theory of F rster’snon-radiation energy transfer, the binding distance was3.0nm. The displacementexperiments showed that LaF3:Ce,Tb nanoparticles could bind to the SiteⅠof BSA. The synchronous fluorescence spectroscopy, CD spectroscopy, tree-dimensionalfluorescence spectroscopy and FT-IR spectroscopy indicated that the stereostructureof BSA was not altered by LaF3:Ce,Tb nanoparticles. It also showed that theLaF3:Ce,Tb nanoparticles had no certain toxic injury effect on BSA2) DPA-LaF3:Tb nanoparticles which surface was coated by sodium citrate and2,6-pyridine dicarboxylic acid was synthesized by hydrothermal method. The sizewas calculated to be about9.0nm. Fluorescence quantum yield was about4.3%. Thespectroscopic properties of prepared nanoparticles were studied by fluorescencespectrum and ultraviolet absorption spectrum, and the structures and morphology ofthem were characterized by IR spectrascopy, X-ray diffraction and transmissionelectronic microscopy. Explored the influence of fluorescence spectroscopy bytemperature and pH.Under the simulative physiology conditions, The interactions of DPA-LaF3:Tbnanoparticles with BSA had been detailedly studied by a variety of spectroscopy.The results indicated that the fluorescence quenching of BSA by DPA-LaF3:Tbnanoparticles was due to the formation of molar ratio of1:1complex through staticquenching. At290,300and310K, the binding constants were calculated to be3.741×104、5.757×104、1.911×104L·mol-1, respectively. According to the Van’t Hoffequation, the thermodynamic parameters indicated that DPA-LaF3:Tb nanoparticlesinteracted with BSA mainly through hydrophobic forces interactions and hydrogenbond forces. The combining process is a spontaneous procedure. According to thetheory of F rster’s non-radiation energy transfer, the binding distance was1.9nm.The displacement experiments showed that DPA-LaF3:Tb nanoparticles could bindto the SiteⅠof BSA. The synchronous fluorescence spectroscopy, CD spectroscopy,tree-dimensional fluorescence spectroscopy and FT-IR spectroscopy indicated thatthe stereostructure of BSA was altered by DPA-LaF3:Tb nanoparticles. It shows thatthe DPA-LaF3:Tb nanoparticles had certain toxic injury effect on BSA.