Distance-dependent interactions between gold nanoparticles and fluorescent molecules with DNA as tunable spacers.
Using stoichiometrically controlled 1:1 functionalization of gold nanoparticles with fluorescent dye molecules in which the dye molecule is held away from the particle surface by a rigid DNA spacer allows precise determination of the distance-dependent effect of the metal nanoparticles on fluorescence intensity. Two dyes were studied, Cy3 and Cy5, with two sizes of nanoparticles, 5 and 10 nm. The larger the particle, the more quenching of the photoluminescence (PL) intensity, due to increased overlap of the dye's emission spectrum with the Au surface plasmon resonance. Fluorescence is quenched significantly for distances somewhat larger than the particle diameter, in good agreement with the predictions of an electrodynamics model based on interacting dipoles. The distance dependence of surface energy transfer behavior, i.e. quenching efficiency, is proportional to 1/d(4), which involves no consideration of the size of the particle and the spectral overlap of the dye and AuNp. This surface energy transfer model is found qualitatively and agrees with the electrodynamic model, though the exponent is greater than 4 for the smaller nanoparticles (5 nm), and smaller than 4 for the larger nanoparticles (10 nm).
Chhabra
Rahul
R
The Biodesign Institute, Arizona State University, Tempe, AZ 85287, USA. Department of Chemistry and Biochemistry, Arizona State University, Tempe, AZ 85287, USA.
Sharma
Jaswinder
J
Wang
Haining
H
Zou
Shengli
S
Lin
Su
S
Yan
Hao
H
Lindsay
Stuart
S
Liu
Yan
Y
D002232:Carbocyanines / Q000737:chemistry; D003198:Computer Simulation; D004247:DNA / Q000737:chemistry*; D005456:Fluorescent Dyes / Q000737:chemistry*; D006046:Gold / Q000737:chemistry*; D053768:Metal Nanoparticles / Q000737:chemistry*; D009693:Nucleic Acid Hybridization; D013056:Spectrophotometry, Ultraviolet
D002232:Carbocyanines; D005456:Fluorescent Dyes; C089187:cyanine dye 3; C085321:cyanine dye 5; D006046:Gold; D004247:DNA