title: Synthesis of luminescent nanoporous silica spheres functionalized with folic acid for targeting to cancer cells.
abstract: Luminescent europium(III)-doped nanoporous silica nanospheres (Eu:NPS) were successfully synthesized, and a folate N-hydroxysuccinimidyl ester (FA-NHS) molecule as a targeting ligand for cancer cells was immobilized on the nanosphere surfaces through mediation of the 3-aminopropyltriethoxysilane (APTES) adlayer. The ordered nanopores were preserved by the immobilization, and the specific surface area decreased only with the APTES immobilization, suggesting that the FA-NHS was predominantly immobilized on the outer surface of the nanopores. The photoluminescence of the nanospheres functionalized with folic acid (FA) exhibited a characteristic peak due to the interactions (e.g., energy transfer) between FA and Eu(3+), and further the orange luminescence could be clearly detected by fluorescence microscopy in air and water. Furthermore, the nanospheres highly dispersed in cell culture medium exhibited nontoxicity in the cellular proliferation stages of the Hela cancer cells and NIH3T3 fibroblasts and specifically bind to the Hela cells. The nanospheres after the binding and uptake also showed intense luminescence from the outer/inner cell surfaces for the culture time of 4 days. Therefore, the luminescent FA-functionalized Eu:NPS nanospheres could be used for specific targeting and imaging abilities for cancer cells.
authors.affiliation: Department of Materials Science and Technology, Nagaoka University of Technology , 1603-1 Kamitomioka, Nagaoka, Niigata 940-2188, Japan.
authors.forename: Motohiro
authors.initials: M
authors.lastname: Tagaya
authors.forename: Toshiyuki
authors.initials: T
authors.lastname: Ikoma
authors.forename: Zhefeng
authors.initials: Z
authors.lastname: Xu
authors.forename: Junzo
authors.initials: J
authors.lastname: Tanaka
mesh_terms: D000818:Animals; D005492:Folic Acid / Q000737:chemistry*; D006367:HeLa Cells; D006801:Humans; D049449:Luminescence; D051379:Mice; D041681:NIH 3T3 Cells; D054118:Nanospheres / Q000737:chemistry*; D009369:Neoplasms / Q000175:diagnosis*; D016062:Porosity; D012822:Silicon Dioxide / Q000737:chemistry*; D014961:X-Ray Diffraction
chemical_list: D012822:Silicon Dioxide; D005492:Folic Acid