Abstract:Numerous approaches have been proposed to mimic natural photosynthesis using artificial antenna systems, such as conjugated polymers (CPs), dendrimers, and J-aggregates. As a result, there is a need to characterize and compare the excitation energy transfer (EET) properties of various natural and artificial antennas. Here we experimentally show that EET in single antennas can be characterized by 2D polarization imaging using the single funnel approximation. This methodology addresses the ability of an individu… Show more
“…Throughout this work we implement a new FRET efficiency parameter called energy funneling efficiency— ε . Due to the novelty of our approach, we refer readers interested in the exact definition of ε to the Method’s section, Supplementary Note 1 and previously published papers 40 , 41 . The main idea behind ε is illustrated by a scheme in Fig.…”
Section: Resultsmentioning
confidence: 99%
“…Modulation depths are dimensionless quantities with values between 0 (isotropically distributed dipoles) and 1 (uniaxially aligned dipoles). Modulation depths and phases have been widely used in single-molecule/single-particle spectroscopy for assessing structural organization and FRET in individual conjugated polymers chains, molecular aggregates, etc 37 , 39 – 41 . Fig.…”
Section: Resultsmentioning
confidence: 99%
“…In order to quantify the FRET efficiency of the sample, we analyze the full polarization portrait via the so-called single funnel approximation 40 , 41 . In this approximation, the polarization portrait is fitted by a model comprised of the linear combination of two components with coefficients (1 − ε ) and ε .…”
A hallmark of Parkinson’s disease is the formation of large protein-rich aggregates in neurons, where α-synuclein is the most abundant protein. A standard approach to visualize aggregation is to fluorescently label the proteins of interest. Then, highly fluorescent regions are assumed to contain aggregated proteins. However, fluorescence brightness alone cannot discriminate micrometer-sized regions with high expression of non-aggregated proteins from regions where the proteins are aggregated on the molecular scale. Here, we demonstrate that 2-dimensional polarization imaging can discriminate between preformed non-aggregated and aggregated forms of α-synuclein, and detect increased aggregation in brain tissues of transgenic mice. This imaging method assesses homo-FRET between labels by measuring fluorescence polarization in excitation and emission simultaneously, which translates into higher contrast than fluorescence anisotropy imaging. Exploring earlier aggregation states of α-synuclein using such technically simple imaging method could lead to crucial improvements in our understanding of α-synuclein-mediated pathology in Parkinson’s Disease.
“…Throughout this work we implement a new FRET efficiency parameter called energy funneling efficiency— ε . Due to the novelty of our approach, we refer readers interested in the exact definition of ε to the Method’s section, Supplementary Note 1 and previously published papers 40 , 41 . The main idea behind ε is illustrated by a scheme in Fig.…”
Section: Resultsmentioning
confidence: 99%
“…Modulation depths are dimensionless quantities with values between 0 (isotropically distributed dipoles) and 1 (uniaxially aligned dipoles). Modulation depths and phases have been widely used in single-molecule/single-particle spectroscopy for assessing structural organization and FRET in individual conjugated polymers chains, molecular aggregates, etc 37 , 39 – 41 . Fig.…”
Section: Resultsmentioning
confidence: 99%
“…In order to quantify the FRET efficiency of the sample, we analyze the full polarization portrait via the so-called single funnel approximation 40 , 41 . In this approximation, the polarization portrait is fitted by a model comprised of the linear combination of two components with coefficients (1 − ε ) and ε .…”
A hallmark of Parkinson’s disease is the formation of large protein-rich aggregates in neurons, where α-synuclein is the most abundant protein. A standard approach to visualize aggregation is to fluorescently label the proteins of interest. Then, highly fluorescent regions are assumed to contain aggregated proteins. However, fluorescence brightness alone cannot discriminate micrometer-sized regions with high expression of non-aggregated proteins from regions where the proteins are aggregated on the molecular scale. Here, we demonstrate that 2-dimensional polarization imaging can discriminate between preformed non-aggregated and aggregated forms of α-synuclein, and detect increased aggregation in brain tissues of transgenic mice. This imaging method assesses homo-FRET between labels by measuring fluorescence polarization in excitation and emission simultaneously, which translates into higher contrast than fluorescence anisotropy imaging. Exploring earlier aggregation states of α-synuclein using such technically simple imaging method could lead to crucial improvements in our understanding of α-synuclein-mediated pathology in Parkinson’s Disease.
“…The authors speculated that the APC protein facilitates super ET from QDs to MoSe 2 via a funnel effect, similar to that previously seen in both artificial and man-made lightharvesting systems, and that this effect relates to the perfect alignment of the dipoles of the chromophores constituting the protein with the in-plane dipole of the 2D material. 98,99 Interfacial Charge Transfer in 2D-vDW Hybrids and Heterostructures. Atomically thin 2D-vDW materials can be combined with appropriately chosen semiconducting materials to obtain donor−acceptor hybrids with type I or type II heterojunctions ( Figure 5) where interfacial CT processes can be initiated.…”
Section: Energy Transfer In 2d-vdw Hybrids and Heterostructuresmentioning
Atomically thin 2D van der Waals (2D-vDW) materials have attracted significant attention for optoelectronic applications in photodetectors, photovoltaics, and quantum information science. Their atomically thin thickness, however, renders them poor absorbers. Hybrid structures of 2D-vDW materials assembled with other semiconducting materials, such as quantum dots, nanowires, polymers, other 2D-vDW materials, or 3D bulk materials, have provided an elegant way to increase light harvesting and carrier generation via interfacial charge and energy transfer interactions.Here we present recent examples focused on the characterization of interfacial charge transfer and energy transfer in 2D-vDW hybrids and heterostructures and methods to modulate and control these processes through band gap engineering, morphology engineering, and external factors. Finally, we discuss potential future directions of research, including scalability from micron-sized flake-based devices to wafer size for commercial deployment, issues with long-term stability and performance, and the ability to extend the spectral range of these 2D hybrids.
“…Circular dichroism [27] and polarization-resolved fluorescence excitation [28] SMS were used to elucidate the pigment ordering in single chlorosomes. Also, the correlation of excitation and emission polarization was used to investigate energy funneling in single LH2 antennas of purple bacteria [29].…”
Abstract:The conversion of solar radiation to chemical energy in plants and green algae takes place in the thylakoid membrane. This amphiphilic environment hosts a complex arrangement of light-harvesting pigment-protein complexes that absorb light and transfer the excitation energy to photochemically active reaction centers. This efficient light-harvesting capacity is moreover tightly regulated by a photoprotective mechanism called nonphotochemical quenching to avoid the stress-induced destruction of the catalytic reaction center. In this review we provide an overview of single-molecule fluorescence measurements on plant light-harvesting complexes (LHCs) of varying sizes with the aim of bridging the gap between the smallest isolated complexes, which have been well-characterized, and the native photosystem. The smallest complexes contain only a small number (10-20) of interacting chlorophylls, while the native photosystem contains dozens of protein subunits and many hundreds of connected pigments. We discuss the functional significance of conformational dynamics, the lipid environment, and the structural arrangement of this fascinating nanomachinery. The described experimental results can be utilized to build mathematical-physical models in a bottom-up approach, which can then be tested on larger in vivo systems. The results also clearly showcase the general property of biological systems to utilize the same system properties for different purposes. In this case it is the regulated conformational flexibility that allows LHCs to switch between efficient light-harvesting and a photoprotective function.
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