Selective turn-on and modulation of resonant energy transfer in single plasmonic hybrid nanostructures

Abstract

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.

Near-Infrared-Fluorescent Probe for Turn-On Lipopolysaccharide Analysis Based on PEG-Modified Gold Nanorods with Plasmon-Enhanced Fluorescence

“…The fluorescence enhancement of the probe cannot be due to the fluorescence resonant energy transfer because of the no fluorescence emission of LPS. Therefore, the donor emission of LPS can be transferred to the acceptor absorption of Cy7. , The fluorescence enhancement may be due to the change of energy transfer between Cy7 and the Au NRs. Before the LPS was added to the probe solution, the hydrophilic chain of PEG on the probe could freely move.…”

“…Therefore, the donor emission of LPS can be transferred to the acceptor absorption of Cy7. 40,41 The fluorescence enhancement may be due to the change of energy transfer between Cy7 and the Au NRs. Before the LPS was added to the probe solution, the hydrophilic chain of PEG on the probe could freely move.…”

Plasmon–Exciton Interactions: Spontaneous Emission and Strong Coupling

“…The energy transfer rate, efficiency, and Förster radius can be modified because of the coupling of the fluorophores with SPs. The energy transfer for donor-acceptor pairs coupled with various metal nanostructures have been investigated, for example, metal NPs, [202][203][204][205] nanorods, [206,207] NP dimers, [208,209] multilayer core-shell NPs, [210] metal film, [211] nanoapertures, [212] and NPs over metal film. [213] The energy transfer efficiency can be expressed as E = γ ET /(γ D + γ ET ), where γ ET is the energy transfer rate between donor and acceptor, and γ D is the sum of the radiative and nonradiative decay rate of the donor.…”

All-optical manipulation of singlet exciton transport in individual supramolecular nanostructures by triplet gating

“…Manipulating the flow of excitation energy (excitons) within supramolecular assemblies of functional organic materials is a key feature to expand their applicability in various fields including sustainable energy conversion [1][2][3] and (quantum) information technology. 4,5 While important design principles for long-range energy transport 2,[6][7][8][9][10][11][12] and the manipulation of energy transport between nanoparticles and molecules 13 are emerging, there is a lack of approaches to manipulate the transport of excitation energy within supramolecular structures in a reliable and reversible manner. In this context, the photosynthetic apparatus in nature provides an intriguing example: 3,14,15 sophisticated pigment-protein complexes direct excitation energy towards a reaction centre via a built-in energy funnel using only one or two species of pigment molecules.…”