Nanometal Surface Energy Transfer in Optical Rulers, Breaking the FRET Barrier

• Published in: Journal of the American Chemical Society 2005-03, Vol.127 (9), p.3115-3119
• Main Authors: Yun, C. S, Javier, A, Jennings, T, Fisher, M, Hira, S, Peterson, S, Hopkins, B, Reich, N. O, Strouse, G. F
• Format: Article
• Language: English
• Subjects: Base Sequence; Biological and medical sciences; Deoxyribonuclease EcoRI - chemistry; Deoxyribonuclease EcoRI - metabolism; DNA - chemistry; DNA - metabolism; Fluorescein - chemistry; Fluorescence Resonance Energy Transfer - methods; Fluorescent Dyes - chemistry; Fundamental and applied biological sciences. Psychology; Gold - chemistry; Models, Molecular; Molecular biophysics; Molecular Sequence Data; Nanotechnology - methods; Photochemistry. Photosynthesis. Bioluminescence; Radiation-biomolecule interaction; Surface Properties
• ISSN: 0002-7863; 1520-5126
• DOI: 10.1021/ja043940i

Optical-based distance measurements are essential for tracking biomolecular conformational changes, drug discovery, and cell biology. Traditional Förster resonance energy transfer (FRET) is efficient for separation distances up to 100 Å. We report the first successful application of a dipole-surface type energy transfer from a molecular dipole to a nanometal surface that more than doubles the traditional Förster range (220 Å) and follows a 1/R 4 distance dependence. We appended a 1.4 nm Au cluster to the 5‘ end of one DNA strand as the energy acceptor and a fluorescein (FAM) to the 5‘ end of the complementary strand as the energy donor. Analysis of the energy transfer on DNA lengths (15, 20, 30, 60bp), complemented by protein-induced DNA bending, provides the basis for fully mapping the extent of this dipole surface type mechanism over its entire usable range (50−250 Å). Further, protein function is fully compatible with these nanometal−DNA constructs. Significantly extending the range of optical based methods in molecular rulers is an important leap forward for biophysics.