Average enhancement factor of molecules-doped coreshell (Ag@SiO2) on fluorescence.

Average enhancement factor (AEF) of a coreshell (Ag@SiO(2)) on the fluorescence of molecules doped within the silica shell is proposed and studied to estimate the overall performance of a large number of coreshells. Using Mie theory and dyadic Green's functions, the enhancement factor (EF) of a coreshell is first calculated for any arbitrarily oriented and located electric dipole embedded in the shell. AEF is then obtained by averaging the individual EF over all possible orientations and positions of the electric dipoles. AEF of a FITC-doped coreshell (radius of Ag core: 25 nm, thickness of shell: 15 nm) irradiated by a laser of 488 nm for FITC's emission at 518 nm is 2.406. It is much smaller than the maximum EF (30.114) of a coreshell containing a single molecule with a radial orientation at its optimal position. For Alexa 430-doped coreshell excited at 428 nm, AEF is 12.34 at the emission of 538 nm.

[1]  L. Novotný,et al.  Enhancement and quenching of single-molecule fluorescence. , 2006, Physical review letters.

[2]  Glenn P. Goodrich,et al.  Plasmonic enhancement of molecular fluorescence. , 2007, Nano letters.

[3]  Qing-Hua Xu,et al.  Separation distance dependent fluorescence enhancement of fluorescein isothiocyanate by silver nanoparticles. , 2007, Chemical communications.

[4]  Xiaohu Gao,et al.  Plasmonic fluorescent quantum dots. , 2009, Nature nanotechnology.

[5]  R. W. Christy,et al.  Optical Constants of the Noble Metals , 1972 .

[6]  H. Y. Chung,et al.  Plasmonic enhancement of Forster energy transfer between two molecules in the vicinity of a metallic nanoparticle: nonlocal optical effects , 2009 .

[7]  V. Shalaev,et al.  Demonstration of a spaser-based nanolaser , 2009, Nature.

[8]  A. Bouhelier,et al.  Fluorescence relaxation in the near-field of a mesoscopic metallic particle: distance dependence and role of plasmon modes. , 2008, Optics express.

[9]  B. MacCraith,et al.  Optimization of Nanoparticle Size for Plasmonic Enhancement of Fluorescence , 2007 .

[10]  L. Eng,et al.  Near-field coupling of a single fluorescent molecule and a spherical gold nanoparticle. , 2007, Optics express.

[11]  J. Liaw,et al.  Enhancement or quenching effect of metallic nanodimer on spontaneous emission , 2010 .

[12]  J. Liaw,et al.  Purcell effect of nanoshell dimer on single molecule's fluorescence. , 2009, Optics express.

[13]  J. Lakowicz,et al.  Metal Enhanced Fluorescence Solution-based Sensing Platform 2: Fluorescent Core-Shell Ag@SiO2 Nanoballs , 2007, Journal of Fluorescence.

[14]  Luis M Liz-Marzán,et al.  Highly controlled silica coating of PEG-capped metal nanoparticles and preparation of SERS-encoded particles. , 2009, Langmuir : the ACS journal of surfaces and colloids.

[15]  Hans C. Gerritsen,et al.  Fluorescence Enhancement by Metal‐Core/Silica‐Shell Nanoparticles , 2006 .

[16]  Hongxing Xu,et al.  Ag@SiO2 core-shell nanoparticles for probing spatial distribution of electromagnetic field enhancement via surface-enhanced Raman scattering. , 2009, ACS nano.

[17]  D. Reinhoudt,et al.  Fluorescence quenching of dye molecules near gold nanoparticles: radiative and nonradiative effects. , 2002, Physical review letters.

[18]  P. C. Chui,et al.  Highly efficient fluorescence of a fluorescing nanoparticle with a silver shell. , 2007, Optics express.

[19]  Denis Boudreau,et al.  FRET enhancement in multilayer core-shell nanoparticles. , 2009, Nano letters.

[20]  Kadir Aslan,et al.  Computational study of fluorescence scattering by silver nanoparticles. , 2007, Journal of the Optical Society of America. B, Optical physics.

[21]  Naomi J Halas,et al.  Fluorescence enhancement by Au nanostructures: nanoshells and nanorods. , 2009, ACS nano.

[22]  Joseph R Lakowicz,et al.  Radiative decay engineering 5: metal-enhanced fluorescence and plasmon emission. , 2005, Analytical biochemistry.

[23]  Vahid Sandoghdar,et al.  Enhancement of single-molecule fluorescence using a gold nanoparticle as an optical nanoantenna. , 2006, Physical review letters.

[24]  Kadir Aslan,et al.  Fluorescent core-shell Ag@SiO2 nanocomposites for metal-enhanced fluorescence and single nanoparticle sensing platforms. , 2007, Journal of the American Chemical Society.