TY - JOUR
T1 - Monolayers of silver nanoparticles decrease photobleaching
T2 - Application to muscle myofibrils
AU - Muthu, P.
AU - Calander, N.
AU - Gryczynski, I.
AU - Gryczynski, Z.
AU - Talent, J. M.
AU - Shtoyko, T.
AU - Akopova, I.
AU - Borejdo, Julian
N1 - Funding Information:
We thank Ewa Goldys for SEM measurements. This publication was made possible by grant RO1 AR048622 from the National Institutes of Health and by a Texas Emerging Technology Fund grant to the University of North Texas Health Science Center's Center for Commercialization of Fluorescence Technologies.
PY - 2008/10/1
Y1 - 2008/10/1
N2 - Studying single molecules in a cell has the essential advantage that kinetic information is not averaged out. However, since fluorescence is faint, such studies require that the sample be illuminated with the intense light beam. This causes photodamage of labeled proteins and rapid photobleaching of the fluorophores. Here, we show that a substantial reduction of these types of photodamage can be achieved by imaging samples on coverslips coated with monolayers of silver nanoparticles. The mechanism responsible for this effect is the interaction of localized surface plasmon polaritons excited in the metallic nanoparticles with the transition dipoles of fluorophores of a sample. This leads to a significant enhancement of fluorescence and a decrease of fluorescence lifetime of a fluorophore. Enhancement of fluorescence leads to the reduction of photodamage, because the sample can be illuminated with a dim light, and decrease of fluorescence lifetime leads to reduction of photobleaching because the fluorophore spends less time in the excited state, where it is susceptible to oxygen attack. Fluorescence enhancement and reduction of photobleaching on rough metallic surfaces are usually accompanied by a loss of optical resolution due to refraction of light by particles. In the case of monolayers of silver nanoparticles, however, the surface is smooth and glossy. The fluorescence enhancement and the reduction of photobleaching are achieved without sacrificing the optical resolution of a microscope. Skeletal muscle myofibrils were used as an example, because they contain submicron structures conveniently used to define optical resolution. Small nanoparticles (diameter ∼60 nm) did not cause loss of optical resolution, and they enhanced fluorescence ∼500-fold and caused the appearance of a major picosecond component of lifetime decay. As a result, the sample photobleached ∼20-fold more slowly than the sample on glass coverslips.
AB - Studying single molecules in a cell has the essential advantage that kinetic information is not averaged out. However, since fluorescence is faint, such studies require that the sample be illuminated with the intense light beam. This causes photodamage of labeled proteins and rapid photobleaching of the fluorophores. Here, we show that a substantial reduction of these types of photodamage can be achieved by imaging samples on coverslips coated with monolayers of silver nanoparticles. The mechanism responsible for this effect is the interaction of localized surface plasmon polaritons excited in the metallic nanoparticles with the transition dipoles of fluorophores of a sample. This leads to a significant enhancement of fluorescence and a decrease of fluorescence lifetime of a fluorophore. Enhancement of fluorescence leads to the reduction of photodamage, because the sample can be illuminated with a dim light, and decrease of fluorescence lifetime leads to reduction of photobleaching because the fluorophore spends less time in the excited state, where it is susceptible to oxygen attack. Fluorescence enhancement and reduction of photobleaching on rough metallic surfaces are usually accompanied by a loss of optical resolution due to refraction of light by particles. In the case of monolayers of silver nanoparticles, however, the surface is smooth and glossy. The fluorescence enhancement and the reduction of photobleaching are achieved without sacrificing the optical resolution of a microscope. Skeletal muscle myofibrils were used as an example, because they contain submicron structures conveniently used to define optical resolution. Small nanoparticles (diameter ∼60 nm) did not cause loss of optical resolution, and they enhanced fluorescence ∼500-fold and caused the appearance of a major picosecond component of lifetime decay. As a result, the sample photobleached ∼20-fold more slowly than the sample on glass coverslips.
UR - http://www.scopus.com/inward/record.url?scp=55949107932&partnerID=8YFLogxK
U2 - 10.1529/biophysj.108.130799
DO - 10.1529/biophysj.108.130799
M3 - Article
C2 - 18556759
AN - SCOPUS:55949107932
SN - 0006-3495
VL - 95
SP - 3429
EP - 3438
JO - Biophysical Journal
JF - Biophysical Journal
IS - 7
ER -