Mesoporous silica-coated NaYF4 nanocrystals: facile synthesis, in vitro bioimaging and photodynamic therapy of cancer cells

Up-conversion nanoparticles (UCNPs) that emit high-energy photons upon excitation by low-energy near-infrared (NIR) radiation are emerging as new optical nanoprobes useful in biomedicine. Herein, the one pot facile synthesis of mesoporous silica-coated NaYF4:Yb/Er nanoparticles has been achieved successfully. The as-prepared product was characterized by X-ray power diffraction (XRD), transmission electron microscopy (TEM) and Brunauer-Emmet-Teller (BET) surface area analyses, respectively. The resulting nanoparticles with a BET area of 800 m(2) g(-1) and an average pore size of 2.6 nm were spherical, highly monodispersed and stable in an aqueous system. Furthermore, the NaYF4:Yb/Er@mesoporous silica nanoparticles also displayed good biocompatibility and could be used for bio-labeling or bio-imaging. Additionally, the results of preliminary photodynamic therapy (PDT) of cancer cells indicated the NaYF4:Yb/Er@mesoporous silica nanoparticles could be used as important photosensitizer carriers for tumor therapy.