title: Labeling TiO2 nanoparticles with dyes for optical fluorescence microscopy and determination of TiO2-DNA nanoconjugate stability.
abstract: Visualization of nanoparticles without intrinsic optical fluorescence properties is a significant problem when performing intracellular studies. Such is the case with titanium dioxide (TiO2) nanoparticles. These nanoparticles, when electronically linked to single-stranded DNA oligonucleotides, have been proposed to be used both as gene knockout devices and as possible tumor imaging agents. By interacting with complementary target sequences in living cells, these photoinducible TiO2-DNA nanoconjugates have the potential to cleave intracellular genomic DNA in a sequence specific and inducible manner. The nanoconjugates also become detectable by magnetic resonance imaging with the addition of gadolinium Gd(III) contrast agents. Herein two approaches for labeling TiO2 nanoparticles and TiO2-DNA nanoconjugates with optically fluorescent agents are described. This permits direct quantification of fluorescently labeled TiO2 nanoparticle uptake in a large population of living cells (>10(4) cells). X-ray fluorescence microscopy (XFM) is combined with fluorescent microscopy to determine the relative intracellular stability of the nanoconjugates and used to quantify intracellular nanoparticles. Imaging the DNA component of the TiO2-DNA nanoconjugate by fluorescent confocal microscopy within the same cell shows an overlap with the titanium signal as mapped by XFM. This strongly implies the intracellular integrity of the TiO2-DNA nanoconjugates in malignant cells.
authors.affiliation: Department of Radiation Oncology Northwestern University Feinberg School of Medicine Chicago, IL 60611, USA.
authors.forename: Kenneth T
authors.initials: KT
authors.lastname: Thurn
authors.forename: Tatjana
authors.initials: T
authors.lastname: Paunesku
authors.forename: Aiguo
authors.initials: A
authors.lastname: Wu
authors.forename: Eric M B
authors.initials: EM
authors.lastname: Brown
authors.forename: Barry
authors.initials: B
authors.lastname: Lai
authors.forename: Stefan
authors.initials: S
authors.lastname: Vogt
authors.forename: Jörg
authors.initials: J
authors.lastname: Maser
authors.forename: Mohammed
authors.initials: M
authors.lastname: Aslam
authors.forename: Vinayak
authors.initials: V
authors.lastname: Dravid
authors.forename: Raymond
authors.initials: R
authors.lastname: Bergan
authors.forename: Gayle E
authors.initials: GE
authors.lastname: Woloschak
mesh_terms: D004247:DNA / Q000737:chemistry*; D005456:Fluorescent Dyes / Q000737:chemistry*; D008856:Microscopy, Fluorescence / Q000379:methods*; D053758:Nanoparticles / Q000737:chemistry*; D036103:Nanotechnology / Q000379:methods*; D014025:Titanium / Q000737:chemistry*; D014965:X-Rays
chemical_list: D005456:Fluorescent Dyes; C009495:titanium dioxide; D004247:DNA; D014025:Titanium