Energy Transfer Pathways Research Articles

Structural insights into a unique PSI-LHCI-LHCII-Lhcb9 supercomplex from moss Physcomitrium patens.

Photosystem I (PSI) possesses a variable supramolecular organization among different photosynthetic organisms to adapt to different light environments. Mosses are evolutionary intermediates that diverged from aquatic green algae and evolved into land plants. The moss Physcomitrium patens (P. patens) has a light-harvesting complex (LHC) superfamily more diverse than those of green algae and higher plants. Here, we solved the structure of a PSI-LHCI-LHCII-Lhcb9 supercomplex from P. patens at 2.68 Å resolution using cryo-electron microscopy. This supercomplex contains one PSI-LHCI, one phosphorylated LHCII trimer, one moss-specific LHC protein, Lhcb9, and one additional LHCI belt with four Lhca subunits. The complete structure of PsaO was observed in the PSI core. One Lhcbm2 in the LHCII trimer interacts with PSI core through its phosphorylated N terminus, and Lhcb9 mediates assembly of the whole supercomplex. The complicated pigment arrangement provided important information for possible energy-transfer pathways from the peripheral antennae to the PSI core.

Logic Control of Directional Long-Range Resonance Energy Transfer On 2D DNA Nanosheet.

By arranging fluorophores in a directional way on a 2D DNA nanosheet that transfers energy from the initial donor to the acceptor through homogeneous Förster resonance energy transfer (homo-FRET), it is found that the photonic wires (PWs) based on cascade long-range resonance energy transfer (LrRET) up to 15.6nm can be effectively achieved through the rational selection of the fluorophores and the adjustment of their position with different distance. Then, logic control of directional energy transfer is achieved with the blocking of the energy transfer pathway, making two tumor-associated microRNA (miRNA) inputs produce an obvious output with the association of tumor diagnosis only when they present simultaneously. This research provides a new thought for development of PWs on 2D DNA nanosheets and a smart application of LrRET-based DNA AND logic control of intracellular miRNA imaging and tumor cells recognition.

Momentum-dependent sum-frequency vibrational spectroscopy of bonded interface layer at charged water interfaces.

Interface-specific hydrogen (H)-bonding network of water directly controls the energy transfer and chemical reaction pathway at many charged aqueous interfaces, yet to characterize these bonded water layer structures remains a challenge. We now develop a sum-frequency spectroscopic scheme with varying photon momenta as an all-optic solution for retrieving the vibrational spectra of the bonded water layer and the ion diffuse layer and, hence, microscopic structural and charging information about an interface. Application of the method to a model surfactant-water interface reveals a hidden weakly donor H-bonded water species, suggesting an asymmetric hydration-shell structure of fully solvated surfactant headgroups. In another application to a zwitterionic phosphatidylcholine lipid monolayer-water interface, we find a highly polarized bonded water layer structure associating to the phosphatidylcholine headgroup, while the diffuse layer contribution is experimentally proven to be negligible. Our all-optic method offers an in situ microscopic probe of electrochemical and biological interfaces and the route toward future imaging and ultrafast dynamics studies.

The benthic food web connects the estuarine habitat mosaic to adjacent ecosystems

Energy flows from land to sea and between pelagic and benthic environments have the potential to increase the connectivity between estuaries and adjacent ecosystems as well as among estuarine habitats. To identify such energy flows and the main trophic pathways of energy transfer in the Minho River estuary, we investigated the spatial and temporal fluctuations of carbon and nitrogen stable isotope ratios in benthic (and their potential food sources) and epibenthic consumers. Sampling was conducted along the estuarine salinity gradient from winter to summer of 2011. We found that the carbon (δ13C = 13C/12C) and nitrogen (δ15N = 15N/14N) stable isotope ratios of the most abundant benthic and epibenthic consumers varied along the salinity gradient. The δ13C values increased seaward, whereas the opposite pattern was found for the δ15N, especially during the summer. The stable isotope ratios revealed two trophic pathways in the Minho estuary food web. The first pathway is supported by phytoplankton and represented by filter feeders such as zooplankton and some deposit feeders, particularly amphipods and polychaetes. The second pathway is supported by detritus and composed essentially of deposit feeders, which by being consumed, allow detritus to be incorporated into higher trophic levels. Spatial and temporal feeding variations in the estuarine benthic food web are driven by hydrology and proximity to adjacent ecosystems (terrestrial, marine). During high river discharge periods, the δ13CPOC (ca. -28‰) and C:NPOM (>10) values suggested an increase of terrestrial-derived OM to the particulate OM pool, which was then used by suspension feeders. During low river discharge periods, marine intrusion increased upriver, which was reflected in benthic consumers' 13C-enriched stable isotope values. No relationship was found between food quality (phytoplankton vs. detritus) and food chain length because the lowest and highest values were associated with freshwater and saltmarsh areas, respectively, both dominated by the detrital pathway. This study demonstrates that benthic consumers enhance the connectivity between estuaries and its adjacent ecosystems by utilizing subsidies of terrestrial and marine origin and that benthic-pelagic coupling is an important energy transfer mechanism to the benthic food web.

Significantly boosted photoelectrochemical water splitting performance by plasmonic enhanced Hematite@MOF composite photoelectrodes

Hematite as a catalyst for photoelectrochemical water splitting offers huge potential, due to its high chemical stability, great abundance, and low cost. However, the low water oxidation kinetics and poor charge transportation have hindered progress towards the manufacture of practical water splitting devices. To tackle these problems, a visible light responsive metal-organic framework (MOF) polyhedral zeolitic imidazolate (ZIF-67), and optimised plasmonic Ag nanorods were incorporated into hematite nanostructures to form a three-component heterojunction photoelectrode. The designed photoanode showed dramatically improved light harvesting in the visible range and enhanced charge transport. A mechanistic investigation allowed the deconvolution of the enhanced performance pathways. First, the Hematite@ZIF-67 core-shell p-n junction enables facile charge carrier transfer between ZIF-67 and hematite. In addition, ZIF-67 also provides active sites for water oxidation and boosts surface oxygen evolution reaction (OER) kinetics. Guided by finite-difference time-domain (FDTD) modelling, Ag nanorods with optimised aspect ratio were incorporated between ZIF-67 and hematite. The Ag nanorods facilitate broadband light absorption and surface charge injection, induced by near-field excitation enhancement and plasmonic resonance energy transfer (PRET) pathways. The design and addition of ZIF-67 and Ag nanorods result in superior performance for a hematite-based photoanode for photoelectrochemical (PEC) water oxidation.

In situ structure of the red algal phycobilisome-PSII-PSI-LHC megacomplex.

In oxygenic photosynthetic organisms, light energy is captured by antenna systems and transferred to photosystem II (PSII) and photosystem I (PSI) to drive photosynthesis1,2. The antenna systems of red algae consist of soluble phycobilisomes (PBSs) and transmembrane light-harvesting complexes (LHCs)3. Excitation energy transfer pathways from PBS to photosystems remain unclear owing to the lack of structural information. Here we present in situ structures of PBS-PSII-PSI-LHC megacomplexes from the red alga Porphyridium purpureum at near-atomic resolution using cryogenicelectron tomography and in situ single-particle analysis4, providing interaction details between PBS, PSII and PSI. The structures reveal several unidentified and incomplete proteins and their roles in the assembly of the megacomplex, as well as a huge and sophisticated pigment network. This work provides a solid structural basis for unravelling the mechanisms of PBS-PSII-PSI-LHC megacomplex assembly, efficient energy transfer from PBS to the two photosystems, and regulation of energy distribution between PSII and PSI.

Mechanism study on gliding arc (GA) plasma reforming: Reaction and energy pathways for H2 production from methanol steam reforming

Aiming on deeply understanding the gliding arc methanol steam reforming (GA-MSR), its reaction mechanism was studied in terms of reaction and energy transfer pathways by combining experiment and plasma kinetics simulation in CH3OH concentration (CME) range of 5%-100%. Via monitoring the consumption and production rates of each species, the roles of species play during GA-MSR are revealed. The important reactive species are identified as H, OH and CH3, which induce the main dehydrogenation pathway of CH3OH→(CH2OH + CH3O) → CH2O → HCO → CO for CH3OH converting to syngas. With the increase of CME, the concentrations of H and CH3 are enhanced, but OH concentration is weakened. The concentration variation trends of the important reactive species regulate that CO2 by-produces at low CME and hydrocarbons do at high CME. In addition, the energy pathways, which are very important but always ignored for plasma reforming, are disclosed advancedly for the energy-strongly coupling GA-MSR. The positive effect of CME on the energy transfer from plasma to chemical energy and the major energy loss pathway of heat loss are uncovered. The energy pathways studies also show why a very high energy efficiency (>80%) could be achieved in GA-MSR, which could be further improved by avoid energy loss from the system.

Metatranscriptomic insights into the microbial electrosynthesis of acetate by Fe2+/Ni2+ addition.

As important components of enzymes and coenzymes involved in energy transfer and Wood-Ljungdahl (WL) pathways, Fe2+ and Ni2+ supplementation may promote the acetate synthesis through CO2 reduction by the microbial electrosynthesis (MES). However, the effect of Fe2+ and Ni2+ addition on acetate production in MES and corresponding microbial mechanisms have not been fully studied. Therefore, this study investigated the effect of Fe2+ and Ni2+ addition on acetate production in MES, and explored the underlying microbial mechanism from the metatranscriptomic perspective. Both Fe2+ and Ni2+ addition enhanced acetate production of the MES, which was 76.9% and 110.9% higher than that of control, respectively. Little effect on phylum level and small changes in genus-level microbial composition was caused by Fe2+ and Ni2+ addition. Gene expression of 'Energy metabolism', especially in 'Carbon fixation pathways in prokaryotes' was up-regulated by Fe2+ and Ni2+ addition. Hydrogenase was found as an important energy transfer mediator for CO2 reduction and acetate synthesis. Fe2+ addition and Ni2+ addition respectively enhanced the expression of methyl branch and carboxyl branch of the WL pathway, and thus promoted acetate production. The study provided a metatranscriptomic insight into the effect of Fe2+ and Ni2+ on acetate production by CO2 reduction in MES.

Dynamic Regulation of the Light-Harvesting System through State Transitions in Land Plants and Green Algae.

Photosynthesis constitutes the only known natural process that captures the solar energy to convert carbon dioxide and water into biomass. The primary reactions of photosynthesis are catalyzed by the photosystem II (PSII) and photosystem I (PSI) complexes. Both photosystems associate with antennae complexes whose main function is to increase the light-harvesting capability of the core. In order to maintain optimal photosynthetic activity under a constantly changing natural light environment, plants and green algae regulate the absorbed photo-excitation energy between PSI and PSII through processes known as state transitions. State transitions represent a short-term light adaptation mechanism for balancing the energy distribution between the two photosystems by relocating light-harvesting complex II (LHCII) proteins. The preferential excitation of PSII (state 2) results in the activation of a chloroplast kinase which in turn phosphorylates LHCII, a process followed by the release of phosphorylated LHCII from PSII and its migration to PSI, thus forming the PSI-LHCI-LHCII supercomplex. The process is reversible, as LHCII is dephosphorylated and returns to PSII under the preferential excitation of PSI. In recent years, high-resolution structures of the PSI-LHCI-LHCII supercomplex from plants and green algae were reported. These structural data provide detailed information on the interacting patterns of phosphorylated LHCII with PSI and on the pigment arrangement in the supercomplex, which is critical for constructing the excitation energy transfer pathways and for a deeper understanding of the molecular mechanism of state transitions progress. In this review, we focus on the structural data of the state 2 supercomplex from plants and green algae and discuss the current state of knowledge concerning the interactions between antenna and the PSI core and the potential energy transfer pathways in these supercomplexes.

Optimizing Upconversion Nanoparticles for FRET Biosensing.

Upconversion nanoparticles (UCNPs) are some of the most promising nanomaterials for bioanalytical and biomedical applications. One important challenge to be still solved is how UCNPs can be optimally implemented into Förster resonance energy transfer (FRET) biosensing and bioimaging for highly sensitive, wash-free, multiplexed, accurate, and precise quantitative analysis of biomolecules and biomolecular interactions. The many possible UCNP architectures composed of a core and multiple shells doped with different lanthanoid ions at different ratios, the interaction with FRET acceptors at different possible distances and orientations via biomolecular interaction, and the many and long-lasting energy transfer pathways from the initial UCNP excitation to the final FRET process and acceptor emission make the experimental determination of the ideal UCNP-FRET configuration for optimal analytical performance a real challenge. To overcome this issue, we have developed a fully analytical model that requires only a few experimental configurations to determine the ideal UCNP-FRET system within a few minutes. We verified our model via experiments using nine different Nd-, Yb-, and Er-doped core-shell-shell UCNP architectures within a prototypical DNA hybridization assay using Cy3.5 as an acceptor dye. Using the selected experimental input, the model determined the optimal UCNP out of all theoretically possible combinatorial configurations. An extreme economy of time, effort, and material was accompanied by a significant sensitivity increase, which demonstrated the powerful feat of combining a few selected experiments with sophisticated but rapid modeling to accomplish an ideal FRET biosensor.

Selective Triplet–Singlet Förster‐Resonance Energy Transfer for Bright Red Afterglow Emission (Adv. Funct. Mater. 11/2023)

Selective Förster-Resonance Energy Transfer In article number 2211604, Shuzo Hirata and co-workers demonstrate the efficient triplet-singlet Förster-resonance energy transfer from the N-fused chromophore to an acceptor leads to the bright red afterglow emission. The selective triplet-singlet energy transfer is due to the high radiation rate from the lowest triplet state facilitated by the out-of-plane molecular vibrations in the N-fused chromophore and near-zero fluorescence suppressing the singlet-singlet energy transfer pathways.

Suppressing the Undesirable Energy Loss in Solution‐Processed Hyperfluorescent OLEDs Employing BODIPY‐Based Hybridized Local and Charge‐Transfer Emitter

Hyperfluorescent organic light‐emitting diodes (HF‐OLEDs) approach has made it possible to achieve excellent device performance and color purity with low roll‐off using noble‐metal‐free pure organic emitter. Despite significant progress, the performance of HF‐OLEDs is still unsatisfactory due to the existence of a competitive dexter energy transfer (DET) pathway. In this contribution, two boron dipyrromethene (BODIPY)‐based donor‐acceptor emitters (BDP‐C‐Cz and BDP‐N‐Cz) with hybridized local and charge transfer characteristics (HLCT) are introduced in the HF‐OLED to suppress the exciton loss by dexter mechanism, and a breakthrough performance with low‐efficiency roll‐off (0.3%) even at high brightness (1000 cd m−2) is achieved. It is demonstrated that the energy loss via the DET channel can be suppressed in HF‐OLEDs utilizing the HLCT emitter, as the excitons from the dark triplet state of such emitters are funneled to its emissive singlet state following the hot‐exciton mechanism. The developed HF‐OLED device has realized a good maximum external quantum efficiency (EQE) of 19.25% at brightness of 1000 cd m−2 and maximum luminance over 60 000 cd m−2, with an emission peak at 602 nm and Commission International de L'Eclairage (CIE) coordinates (0.57, 0.41), which is among the best‐achieved results in solution‐processed HF‐OLEDs. This work presents a viable methodology to suppress energy loss and achieve high performance in the HF‐OLEDs.

Access to Azetidines via Gold Mediated Energy Transfer Photocatalysis.

The area of energy transfer photocatalysis to generate four-membered rings is experiencing an unprecedented level of activity. Here, we report an operationally simple method toward azetidines from 2-isoxasoline-3-carboxylates and alkenes, using [Au(cbz)(NHC)] complexes as photocatalysts. The procedure enables the reaction for a wide range of substrates. Mechanistic studies confirm the energy transfer pathway. This contribution adds to the earlier reported use of these gold catalysts as a potentially versatile tool in energy transfer chemistry and catalysis.

Ratiometric fluorescent nanoprobes based on coumarin dye-functionalized carbon dots for bisulfite detection in living cells and food samples

As an important food additive, extensive intake of bisulfite (HSO3−) often leads to serious related diseases. However, the reliability and accuracy of HSO3− detection remains an outstanding challenge because the majority of previously reported sensors for HSO3− have been evaluated by the single-channel signal output. Herein, we constructed a ratiometric fluorescent nanoprobe, Coum-CDs, by covalently coupling the coumarin dye (Coum) onto the surface of yellow emissive carbon dots (Y-CDs) via amide bonds. The Coum-CDs themselves showed peculiar dual fluorescence emission at 480 and 565 nm under single-wavelength excitation. However, upon treatment with HSO3−, the π-conjugation structure of Coum was destroyed due to the selectively nucleophilic reaction between the C-4 atom of Coum and HSO3−, which shut off the pathway of fluorescence resonance energy transfer from Coum to Y-CDs. As a result, the fluorescence emission of Coum-CDs at 565 nm decreased significantly, accompanied by a slight change in fluorescence intensity at 480 nm, allowing the ratiometric detection of HSO3−. In addition, the nanoprobe Coum-CDs displays a very low detection limit of 15 nM and excellent selectivity without interference from other relevant analytes, especially reactive sulfur-containing species. Importantly, preliminary experiments showed that the Coum-CDs have been successfully applied to ratiometric monitoring of exogenous and endogenous HSO3− in living cells, as well as the quantitative measurement of HSO3− in sugar and wine.

2D defect-engineered Ag-doped γ-Fe2O3/BiVO4: The effect of noble metal doping and oxygen vacancies on exciton-triggering photocatalysis production of singlet oxygen

The selectivity of singlet oxygen (1O2) holds promising applications in complex environmental systems due to its ability to preferentially oxidize target pollutants. Usually, 1O2 in photocatalytic systems is generated via the electron transfer pathway and •O2− plays an important role as an intermediate, while the exciton-based energy transfer pathway for 1O2 generation has been less studied. Here, a 2D Ag-γ-Fe2O3/BiVO4 with oxygen vacancies was designed which was capable of generating 1O2 by an exciton-based energy transfer-dominated approach, as strongly demonstrated by the results of steady-state fluorescence spectroscopy and phosphorescence spectroscopy. In the Z-type heterojunction photocatalyst system, Ag acted as an electron mediator to promote not only the generation of free carriers but also the generation of singlet excitons, while the appropriate concentration of oxygen vacancies further promotes the exciton-triggering photocatalysis production of 1O2. The Ag-γ-Fe2O3/BiVO4 could degrade 99.4% of sulfadiazine within 90 min, and 1O2 played an important role in the degradation of sulfadiazine, as shown by EPR and active species capture experiments. Ecotoxicity predictions indicated that the main byproducts of sulfadiazine degradation by Ag-γ-Fe2O3/BiVO4 were low in toxicity. The prepared photocatalysts provide a new idea for obtaining 1O2 and designing photocatalysts with selectivity.

Dy-incorporated organic-inorganic hybrid polyoxometalates with photoluminescence property

Two new organic-inorganic hybrid polyoxometalate [N(CH3)4]3K2[Dy(C7H5O2)(H2O)2(α-PW11O39)]·13H2O (1) and [N(CH3)4]3K2[Dy(C7H5O3)(H2O)2(α-PW11O39)]·13H2O (2) were prepared via the reaction of K14[P2W19O69(H2O)]·24H2O, DyCl3·6H2O and organic ligands, which were further characterized by IR spectrum, TG analysis, and X-ray single-crystal diffraction. Structural analysis reveals that 1 and 2 consist of polyanion [Dy(L)(H2O)2(α-PW11O39)]5– (L = C7H5O2 (1a), C7H6O3 (2a)), three [N(CH3)4]+ cations, two K+ cations for the charge balance, and thirteen water molecules. The excitation and emission spectra and decay time curves prove the existence of different potential energy transfer pathways, and the decay time curves indicate POM components can sensitize the emission of Dy3+ ion and lifetimes were prolonged.

Design of phase change composite with hierarchical energy-transfer pathway via laser-induced graphene for efficient energy storage, conversion, and utilization

To achieve efficient energy harvesting and utilization, phase change composites (PCCs) with high energy storage density, thermal conductivity, and photothermal conversion ability have always been a research focus. Herein, a three-dimensional (3D) porous laser-induced graphene supporting matrix with the plant leaf-mimetic network (PLMN) for loading phase change materials (PCMs) was fabricated by direct laser writing on polybenzoxazine resin (Poly(PH-ddm)). PLMN is designed to consist of laser-induced graphene (LIG) with both vein-like and mesophyll-like structures, the former one mainly responsible for efficient energy harvesting as well as fast heat flow transport and the latter one as the dominant part for high encapsulation of polyethylene glycol (PEG) PCM. The obtained plant leaf-mimetic composite (PLMC) exhibits a large latent heat of 162.3 J/g and high thermal conductivity of 1.18 W/m·K (391.67 % increment than pure PEG). PLMC also shows a high solar energy conversion efficiency of 84.1 %, which benefits from the well-designed PLMN structure as well as the thermal insulation effect of the resin layer. In addition, the resin layer provides mechanical support and flame-retardant function, ensuring the use safety of PLMC. The applications of PLMC for efficient utilization of solar energy and thermal management of electronics have been well-demonstrated. This work provides novel insights into the design and fabrication of PCCs with great potential in solar energy utilization and other thermal energy-related processes.

Vibrational Energy Redistribution and Polaritonic Fermi Resonances in the Strong Coupling Regime.

Intramolecular vibrational energy redistribution (IVR) plays a significant role in cavity-modified chemical reaction rates. As such, understanding the fundamental mechanisms by which the cavity modifies the IVR pathways is a fundamental step toward engineering the effect of the confined electromagnetic modes on the outcome of chemical processes. Here we consider an ensemble of M two-mode molecules with intramolecular anharmonic couplings interacting with an infrared cavity mode and consider their quantum dynamics and infrared spectra. Polaritonic Fermi resonances involving fundamental and overtone states of the polaritonic subsystem mediate efficient energy transfer pathways between otherwise off-resonant molecular states. These pathways are of collective nature, yet enabled by the intramolecular anharmonic couplings. Hence, through polaritonic Fermi resonances, cavity excitation can efficiently spread toward low-frequency modes while becoming delocalized over several molecules.

Development of surrogate models for evaluating energy transfer quality of high-speed railway pantograph-catenary system using physics-based model and machine learning

High-speed railway pantograph-catenary system is the only energy transfer pathway to drive a train operation. Energy transfer quality deteriorates with the increasing train speed and harsh service environment, thereby quickly and accurately evaluating the energy transfer quality is very important to guarantee the normal operation of a train. In this study, firstly, the physics-based model to simulate the dynamic interaction of pantograph-catenary system is established and validated. Eleven input parameters involve the essential line design and train operation parameters, and the output parameters that are crucially responsible for energy transfer quality are obtained by feature extraction. Secondly, a sampling strategy is employed to construct the input sampling points, based on which the outputs are computed via physics-based model, then combining them the dataset is obtained. Thirdly, five tree-based classification surrogate models are developed and compared to assess the level of energy transfer quality. Finally, eight regression surrogate models are developed in replacing physics-based model to evaluate the essential values of energy transfer quality. It is found that the gradient boosting decision tree (GBDT)-based surrogate model is the optimal classification model and the multi-layer feed-forward deep neural network (MLF-DNN)-based surrogate model for the optimal regression model. The two surrogate models are expected to quickly find the optimal design parameters and improve the operation control of trains of high-speed railway for the purpose of enhancing the energy transfer quality if coupled with optimization procedure.

Intermolecular resonance energy transfer between two lutein pigments in light-harvesting complex II studied by frenkel exciton models.

The energy transfer pathways in light-harvesting complex II are complicated and the discovery of the energy transfer between the two luteins revealed an unelucidated important role of carotenoids in the energy flow. This energy transfer between the two S2 states of luteins was for the first time investigated using Frenkel exciton models, using a hybrid scheme of molecular mechanics and quantum mechanics. The results show the energy flow between the two luteins under the Förster resonance energy transfer mechanism. The energy transfer caused by energy level resonance occurs in configurations with small energy gaps. This energy transfer pathway is particularly sensitive to conformation. Moreover, according to the statistical characteristics of the data of the energy gaps and coupling values between LUTs, we proposed stochastic exciton Hamiltonian models to facilitate clarification of the energy transfer among pigments in antenna complexes.