Synthesis Of Aminoisophthalic Acid Sensitized LaF₃:Tb Luminescent Nanoparticles And Application Of Cellular Imaging

Cell-labeling is one of the most important technologies in biological research, which growing trends are to strengthen the bio-compatibility, to enhance the ability for trace and to achieve living body and cellular imaging. Therefore, it is still one of the important steps to develop biomarkers materials with good biocompatibility and excellent labeling performance. Rare earth luminescent nanomaterials showed obvious superiority in biocompatibility comparing to traditional flourescent materials due to their unique optical and chemical properties, Currently, the maximum excitation wavelengths of most synthesized rare earth down-conversion nanoparticlesmostly located in the far ultraviolet region (< 300 nm), and far ultraviolet light of have certain killing effect on biological molecules and cells; this greatly limits the applications of rare earth down-conversion nanoparticles in the field of biological markers and Cellular imaging. This study attempts to synthesize rare earth down-conversion nanoparticles that the excitation wavelength was located in the near ultraviolet region, with strong luminous intensity and good biocompatibility.With sodium citrate as ligand and APA as sensitizer, the APA-LaF3:Tb luminescent nanoparticles were firstly one step synthesized by hydrothermal method. And the synthesis conditions were optimized based on the luminescence intensity and water-solubility of APA-LaF3:Tb nanoparticles solution. The results showed that the best conditions to synthesize APA-LaF3:Tb nanoparticles were as followed:the pH value of the reaction solution was 8.0; the reaction time was 1.0h; the reaction temperature was 130?; the more ration of APA to Tb3+ ion was 5:1; the mole ration of sodium citrate to rare earth ion was 0.6:1; the mole ration of ammonium fluoride to rare earth ion was 3:1. The fluorescence spectra demonstrated that the excitation and emission peak were at 348nm and 544nm, respectively; its lifetime was 2.55 ms and it was good solubility in water.APA-LaF3:Tb nanoparticles were characterized by many methods. The XRD pattern showed that the as-prepared DPA-LaF3:Tb particles were hexagon. The TEM image indicated that the nanoparticles were two kinds of shapes, one is spherical with the average size of about 10 nm, the other is rodlike, The length isabout 20 nm and width is about 5 nm. Via measuring the lightlife of as-prepared APA-LaF3:Tb nanoparticles, it showed that APA is coated on the surface of the particles.Compared with LaF3:Tb nanoparticles, the excitation wavelength of APA-LaF3:Tb is redshift 109 nm, luminescence intensity increased by 25 times.On the basis of synthesis, APA-LaF3:Tb nanoparticles were Amino modified. Amino modified APA-LaF3:Tb nanoparticles were characterized by transmission electron microscope (TEM) and Infrared spectrum (IR) The TEM image indicated that the nanoparticles were spherical with the average size of about 30 nm. The result of IR showed that APA-LaF3:Tb nanoparticles have been successfully Amino modified.After surface modification, the rabbit anti-CEA8 antibodiy were covalently coupled with the APA-LaF3:Tb to form the APA-LaF3:Tb-Ab conjugates, and then used as the biolabels for the immunolabelling and imaging of live HeLa cells, which was achieved by the specific recognization between the rabbit anti-CEA8 antibodiy and the carcinoembryonic (CEA) antigen, a cancer biomarker expressed on the surface of HeLa cells. This method for the immunolabelling of HeLa cells was found to be well specific, effective, time efficient, and free of autofluorescence.