Department of Materials Science and Engineering, Tokyo Institute of Technology, Ookayama 2-12-1-S8-44, Meguro-ku, Tokyo 152-8552, Japan.
Nanoscale. 2017 Jan 26;9(4):1511-1519. doi: 10.1039/c6nr08740j.
Förster resonant energy transfer (FRET) is a nonradiative process by which the energy of light absorbed by a donor molecule is transferred to an acceptor molecule over a distance of several nanometers. FRET plays a crucial role in photosynthesis and nature-inspired artificial light-harvesting systems that are being explored for use in energy conversion applications. Localized plasmons of metal nanoparticles can potentially lead to a significant increase of FRET efficiency and effective donor-acceptor distance. Here, we prepare hybrid nanostructures composed of a gold nanorod and donor and acceptor molecules covalently attached to its surface, and study them on the level of a single nanoparticle by simultaneous dark-field scattering, fluorescence imaging and spectroscopy. The single-particle approach enables selective excitation of the longitudinal plasmon of the gold nanorod by polarization of the excitation light. The emission intensity of the acceptor molecules can be controllably and reversibly modulated over a wide range by the polarization angle, thus enabling a selective turn-on of the FRET process and control over the emission color of the hybrid nanostructure. Numerical simulations show that the interactions of the donor and acceptor molecules with the plasmon lead to an increase of the energy transfer efficiency by a factor of ∼65. These findings represent the concept of a novel colour switching approach and could pave the way for innovative applications in optoelectronics and nanophotonics.
Förster 共振能量转移（FRET）是一种非辐射过程，其中光被供体分子吸收的能量通过几个纳米的距离转移到受体分子。FRET 在光合作用和受自然启发的人工光捕获系统中起着至关重要的作用，这些系统正在探索用于能量转换应用。金属纳米粒子的局域等离子体有可能导致 FRET 效率和有效供体-受体距离的显著增加。在这里，我们制备了由金纳米棒和共价连接到其表面的供体和受体分子组成的杂化纳米结构，并通过同时暗场散射、荧光成像和光谱学在单个纳米颗粒水平上对其进行研究。单颗粒方法通过将激发光的偏振选择性地激发金纳米棒的纵向等离子体。通过调节偏振角，可以在很宽的范围内对受体分子的发射强度进行可控且可逆的调制，从而可以选择性地开启 FRET 过程并控制杂化纳米结构的发射颜色。数值模拟表明，供体和受体分子与等离子体的相互作用导致能量转移效率增加了约 65 倍。这些发现代表了一种新型颜色切换方法的概念，并为光电学和纳米光子学的创新应用铺平了道路。
