Synthesis Of NaYF₄:Yb,Tm Nanoparticles Emitting Near-Infrared Luminescence And Their Application In Biological Analysis

Upconversion (UC) luminescent materials are the material that can emit high energetic short wavelength under the low energetic wavelength. Because of their unique optical properties, Rare-earth doped UCNPs have got much attention in the field of biological analysis. Rare-earth doped UCNPs are usually excited by the 980 nm, and the light in the visible area emitted from the particles is used in biological analysis. According to the current research, Rare-earth doped UCNPs can emit the near-infrared 800 nm light with excitation, due to the infrared light area belonging to biological tissue optical window, and the near infrared light have the characteristics of high transmittance and high singal-to-noise. Therefore, in this work, the near infrared emitted NaYF4:Yb,Tm UCNPs were synthesized by solvothermal method, then, the UCNPs are used to the tumor cell imaging.We studied some the aspects that affected the properties of the particles, such as the pH of POCA and the volume of POCA, the reaction temperature, the raction time, the mole ratio of NH4F to rareearth ion, the mole ratio of Na to rareearth ion, the reaction medium, and the rare-earth content. The NaYF4:Yb,Tm nanoparticles syntheied under different conditions were charactered by luminescent spectra, XRD, TEM. The results showed that NaYF4:Yb,Tm nanoparticles syntheied had good water-solubility which was the hexagonal phase and the high crystallinity,which had high intensity and the main emission wavelength was 800 nm.the TEM image indicated that the prepared NaYF4:Yb,Tm nanoparticles which was syntheied with the volume 625 μL of pH POCA, the mole ratio of NH4F to rare-earth ion 7:1, the mole ratio of Na to rare-earth ion 4:1, the content of Yb 60%, the Tm content 1.5%, and reacted at 200℃ for 5 h, were spherical and well dispersed.These UCNPs were coated with a thin layer of SiO2 to form core-shell NPs and further modified with amino groups via a typical Stober method. Then, the rabbit anti-CEA antibodiy (Ab) were covalently coupled with the UCNPs to form the UCNPs-Ab conjugates. Finally, the UCNPs-Ab conjugates were used as the biolabels for the immunolabelling and imaging of live Hela cells. The result showed that the areas around Hela cells gave out light under the dark filed with the irradiation of 980 nm, the NaYF4:Yb,Tm nanoparticles synthed can be used for cell labeling and imaging.