Gold and Silver Nanowires for Fluorescence Enhancement

摘要: One-dimensional (1-D) noble metallic nanoscale materials, particularly silver or gold have been attracting wide interest due to their unique optical, electronic, catalytic and mechanical properties. Recently significant has devoted ultrasensitive detection of trace analytes down a single molecule level. Various strategies lower the limit for fluorescence-based sensors include increasing signal from fluorescent dyes that indicate presence specific analyte. Metals such as with nanometer scale dimensions (in 1-100 nm range) exhibit remarkable optical effect known localised surface plasmon resonance (Hutter Fendler 2001, Lakowicz et all 2002 2003, Geddes 2003a, 2003b,Liebermann Knoll 2000, Tarcha 1998, 1999, Sokolov Kummerlen 1993, Felidi Jensen at 2000), which is resonant photons inducing coherent oscillations conduction band electrons. The confinement nanoparticle can increase amplitude electromagnetic wave by much orders magnitude. This strong field decays exponentially over distance comparable nanostructures size. Correspondingly, light intensity near (proportional square wave’s amplitude) also significantly increased. In way metal particles through plasmonic confinement, effectively focus resonantly coupled light. As result, radiative properties molecules in proximity nanoparticles, absorption, fluorescence, Rayleigh scattering Raman be enhanced magnitude, when certain conditions are met. particular, nanoparticles modify close fluorophores. nearby not only enhance fluorophore quantum yield but stabilize adjacent fluorophores against photobleaching, further enhancing utility fluorescence sensing imaging. However, very surface, quenching competes these favorable effects2 it dominates within 5 particles. At larger distances, enhancement starts override reaches its maximum about 10 (Kerker 1982, Gersten Nitzan 1985). metalfluorophore separation, progressively decreases. Early studies using colloidal fractals deposited electrochemically on glass substrates showed substantial visible range (Geddes 2003b, 1993). Larger enhancements were created more