TY - JOUR
T1 - Radiative decay engineering
T2 - 2. Effects of silver island films on fluorescence intensity, lifetimes, and resonance energy transfer
AU - Lakowicz, Joseph R.
AU - Shen, Yibing
AU - D'Auria, Sabato
AU - Malicka, Joanna
AU - Fang, Jiyu
AU - Gryczynski, Zygmunt
AU - Gryczynski, Ignacy
N1 - Funding Information:
This work was supported by the NIH National Center for Research Resources, RR-08119, with additional support from the Juvenile Diabetes Foundation International, 1-2000-546, and the American Diabetes Foundation. The authors thank the referees for the detailed comments and suggestions which improved the manuscript.
PY - 2002/2/15
Y1 - 2002/2/15
N2 - Metallic surfaces can have unusual effects on fluorophores such as increasing or decreasing the rates of radiative decay and the rates of resonance energy transfer (RET). In the present article we describe the effects of metallic silver island films on the emission spectra, lifetimes, and energy transfer for several fluorophores. The fluorophores are not covalently coupled to the silver islands so that there are a range of fluorophore-to-metal distances. We show that proximity of fluorophores to the silver islands results in increased fluorescence intensity, with the largest enhancement for the lowest-quantum-yield fluorophores. Importantly, the metal-induced increases in intensity are accompanied by decreased lifetimes and increased photostability. These effects demonstrate that the silver islands have increased the radiative decay rates of the fluorophore. For solvent-sensitive fluorophores the emission spectra shifted to shorted wavelengths in the presence of the silver islands, which is consistent with a decrease of the apparent lifetime for fluorophores near the metal islands. We also observed an increased intensity and blue spectral shift for the protein human glyoxalase, which displays a low quantum yield for its intrinsic tryptophan emission. In this case the blue shift is thought to be due to increased emission from a buried low-quantum-yield tryptophan residue. Increased intensities were also observed for the intrinsic emission of the nucleic acid bases adenine and thymine and for single-stranded 15-mers poly(T) and poly(C). And finally, we observed increased RET for donors and acceptors in solution and when bound to double-helical DNA. These results demonstrate that metallic particles can be used to modify the emission from intrinsic and extrinsic fluorophores in biochemical systems.
AB - Metallic surfaces can have unusual effects on fluorophores such as increasing or decreasing the rates of radiative decay and the rates of resonance energy transfer (RET). In the present article we describe the effects of metallic silver island films on the emission spectra, lifetimes, and energy transfer for several fluorophores. The fluorophores are not covalently coupled to the silver islands so that there are a range of fluorophore-to-metal distances. We show that proximity of fluorophores to the silver islands results in increased fluorescence intensity, with the largest enhancement for the lowest-quantum-yield fluorophores. Importantly, the metal-induced increases in intensity are accompanied by decreased lifetimes and increased photostability. These effects demonstrate that the silver islands have increased the radiative decay rates of the fluorophore. For solvent-sensitive fluorophores the emission spectra shifted to shorted wavelengths in the presence of the silver islands, which is consistent with a decrease of the apparent lifetime for fluorophores near the metal islands. We also observed an increased intensity and blue spectral shift for the protein human glyoxalase, which displays a low quantum yield for its intrinsic tryptophan emission. In this case the blue shift is thought to be due to increased emission from a buried low-quantum-yield tryptophan residue. Increased intensities were also observed for the intrinsic emission of the nucleic acid bases adenine and thymine and for single-stranded 15-mers poly(T) and poly(C). And finally, we observed increased RET for donors and acceptors in solution and when bound to double-helical DNA. These results demonstrate that metallic particles can be used to modify the emission from intrinsic and extrinsic fluorophores in biochemical systems.
UR - http://www.scopus.com/inward/record.url?scp=0037083537&partnerID=8YFLogxK
U2 - 10.1006/abio.2001.5503
DO - 10.1006/abio.2001.5503
M3 - Article
C2 - 11814297
AN - SCOPUS:0037083537
SN - 0003-2697
VL - 301
SP - 261
EP - 277
JO - Analytical Biochemistry
JF - Analytical Biochemistry
IS - 2
ER -