Detection of low quantum yield fluorophores and improved imaging times using metallic nanoparticles

L. C. ESTRADA; J. ROBERTI; S. SIMONELLI; V. LEVI; P. ARAMENDÍA; O.E. MARTÍNEZ

JOURNAL OF PHYSICAL CHEMISTRY B

ACS PUB.

Año: 2012 vol. 116 p. 2306 - 2313

1089-5647

The behavior of a fluorophore near a gold nanoparticle is rationalized by a theoretical description of the parameters that modify the fluorescence emission: nanoparticle-fluorophore distance, fluorescence quantum yield (0), and fluorophore absorption and emission spectra, to find optimum conditions for designing fluorophore-nanoparticle probes. The theoretical maximum gain in brightness of the nanoparticle-fluorophore system with respect to the isolated molecule increases almost inversely proportional to 0. The brightness enhancement in imaging experiments in vitro was assessed by using Au-SiO2 core-shell nanoparticles deposited on glass. A ~13-fold emission brightness enhancement for weakly fluorescent molecules was observed. A significant increase in fluorophore photostability, rendering longer imaging times, was obtained for fluorophores interacting with gold nanoparticles incorporated by endocytosis in cells. Our results illustrate a way to increase imaging times and to study molecules in the vicinity of a metallic nanoparticle after photobleaching of background fluorescence.