%0 Journal Article
%T A Method to Improve the Up-Conversion Fluorescence of Polymer Modified NaYF<sub>4</sub>:Yb,Er(Tm) Nanocomposites
%A Weina Cui
%A Siyu Ni
%A Shunan Shan
%A Xingping Zhou
%J World Journal of Nano Science and Engineering
%P 41-46
%@ 2161-4962
%D 2012
%I Scientific Research Publishing
%R 10.4236/wjnse.2012.22007
%X The modification of NaYF<sub>4</sub>:Yb,Er(Tm) nanoparticles synthesized in the presence of an ionic surfactant is critical to their application in biological fields for better solubility and biocompatibility. In this work, NaYF<sub>4</sub>:Yb,Er(Tm) was transformed from insoluble, inactive to hydrophilic, biocompatible via ligand exchange modification with polyacrylic acid (PAA). Ligand exchange was carried out at room temperature when a colloidal solution of NaYF<sub>4</sub>:Yb,Er(Tm) in tetrahydrofuran (THF) was treated with excess PAA. The PAA modified NaYF<sub>4</sub>:Yb,Er(Tm) nanoparticles got better surface properties but with declined inner up-conversion fluorescence. Generally, coating an analogous layer of material outside the core nanoparticles can improve the optical properties of the core. Accordingly, NaYF<sub>4</sub>:Yb,Er(Tm)/NaYF<sub>4</sub> nanoparticles were synthesized before PAA modification to avoid the optical intensity decaying. The result of fluorescence test proved that the water soluble NaYF<sub>4</sub>:Yb,Er(Tm)/NaYF<sub>4</sub>/PAA nanocomposites had a sound up-conversion property compared with that of NaYF<sub>4</sub>:Yb,Er(Tm)/PAA. Furthermore, the up-conversion fluorescence property of the nanocomposite varied with the doping ratio of Er(Tm) to Yb and the possible mechanism for this change was also discussed.
%K Doping Ratio
%K Fluorescence
%K Ligand Exchange
%K Polyacrylic Acid
%K Sodium Yttrium Fluoride
%K Surface Modification
%U http://www.scirp.org/journal/PaperInformation.aspx?PaperID=20155