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Super-resolution Mapping of Enhanced Emission by Collective Plasmonic Resonances
摘要： Plasmonic particle arrays have remarkable optical properties originating from their collective behavior, which results in resonances with narrow line widths and enhanced electric fields extending far into the surrounding medium. Such resonances can be exploited for applications in strong light?matter coupling, sensing, lasing, and light harvesting, nonlinear nanophotonics, solid-state lighting. However, as the lattice constants associated with plasmonic particle arrays are on the order of their resonance wavelengths, mapping the interaction between point dipoles and plasmonic particle arrays cannot be done with diffraction-limited methods. Here, we map the enhanced emission of single fluorescent molecules coupled to a plasmonic particle array with ～20 nm in-plane resolution by using stochastic super-resolution microscopy. We find that extended lattice resonances have minimal influence on the spontaneous decay rate of an emitter but instead can be exploited to enhance the outcoupling and directivity of the emission. Our results can guide the rational design of future optical devices based on plasmonic particle arrays.
关键词： light?matter interaction,nanophotonics,single molecule localization,collective resonances,plasmonics,super-resolution microscopy
更新于2025-11-25 10:30:42
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A Speckle-Free Angular Interrogation SPR Imaging Sensor Based on Galvanometer Scan and Laser Excitation
摘要： A speckle-free fast angular interrogation surface plasmon resonance imaging (SPRi) sensor based on a diode-pumped all-solid-state laser and galvanometer is reported in this work. A bidirectional scan using a galvanometer realizes the fast scanning of the incidence angle. The experimental results showed that the time needed for completing an SPR dip measurement was decreased to 0.5 s. And through cascading an immovable diffuser and two diffusers rotating in opposite directions, laser speckle was eliminated. The dynamic detection range and the sensitivity reached 4.6 × 10?2 and 1.52 × 10?6 refractive index unit (RIU), respectively, in a 2D array sensor when the angle scanning range was set as 7.5°. More importantly, the results demonstrated that the angular interrogation SPR imaging sensor scheme had the capability to perform fast and high-throughput detection of biomolecular interactions at 2D sensor arrays.
关键词： Speckle-free,Biomolecule interaction,Angular interrogation,Surface plasmon resonance imaging sensor
更新于2025-11-25 10:30:42
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Endowing Light-Inert Aqueous Surfactant Two-Phase System with Photo Responsiveness by Introducing a Trojan Horse
摘要： The ability to modulate the phase behavior of aqueous surfactant two-phase (ASTP) system reversibly with light is of great importance in both fundamental and applied science. Thus far, most of the light-responsive ASTP systems are based on covalent-modification of the component molecules. In this article, we for the first time achieve photo-responsiveness in a light-inert ASTP system by physically introducing a photo-trigger with the aid of an Trojan Horse. The ATPS system formed with sodium laurate (SL) and dodecyl tributyl amomium (DBAB) doesn’t show light responsiveness by physically mixing a light responsive azobenzene compound, 2-(4-(phenyldiazenyl)phenoxy)actate sodium (Azo). However, in the presence of the host-guest complex SL@β-CD formed with β-CD and sodium laurate (SL), the ASTP turns quickly into a homogenous suspension under visible light, which recovers to the original ASTP state again under 365 nm UV irradiation. Because the SL@β-CD complex exists harmonically with the ASTP, it can be viewed as a “Trojan horse” that becomes fatal only when the encapsulated SL is triggered to release. In the presence of the Trojan horse, the photo-responsiveness of the ASTP can be manipulated reversibly by alternatively exerting UV and visible light. Using this strategy, we are able to collect trace amount of oily components from water. The current strategy points out that it is possible to achieve light-responsiveness in light-inert systems with physical method, which may have profound impact both on the fundamental and applied science.
关键词： Cyclodextrin,Azobenzene,Trojan horse,Host-Guest Interaction,Aqueous surfactant two-phase system,Photo-Responsive
更新于2025-11-25 10:30:42
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Measuring the interaction of transcription factor Nrf2 with its negative regulator Keap1 in single live cells by an improved FRET/FLIM analysis
摘要： Transcription factor NF-E2 p45-related factor 2 (Nrf2) and its principal negative regulator, Kelch-like ECH-associated protein 1 (Keap1), comprise a molecular effector and sensor system that robustly responds to perturbations of the cellular redox homeostasis by orchestrating a comprehensive cytoprotective program. Under homeostatic conditions, Nrf2 is a short-lived protein, which is targeted for ubiquitination and proteasomal degradation. Upon encounter of electrophiles, oxidants or pro-inflammatory stimuli, the cysteine sensors in Keap1 are chemically modified, rendering Keap1 unable to target Nrf2 for degradation, and consequently leading to accumulation of the transcription factor and enhanced transcription of cytoprotective genes. Detailed understanding of the protein-protein interactions between Nrf2 and Keap1 has been achieved by use of various in vitro systems, but few assays are available to assess these interactions in the context of the living cell. We previously developed an imaging-based FLIM/FRET methodology to visualise and measure the interaction between Nrf2 and Keap1 in single cells. Here, our goal was to improve this methodology in order to increase throughput and precision, and decrease cell-to-cell variability. To eliminate the possibility of orientation bias, we incorporated a flexible linker between Keap1 and the FRET acceptor fluorescent protein tag. To ensure the correct image capture of Nrf2 fused to the FRET donor fluorescent protein tag, we matched the maturation time of the fluorescent tag to the half-life of the endogenous Nrf2, by using sfGFP as the FRET donor. Using a global binning approach increased the assay throughput, whereas including the measured Instrument Response Function in the analysis improved precision. The application of this methodology revealed a strong covariation of the results with the expression level of the acceptor. Taking the acceptor level into account circumvented cell-to-cell variability and enhanced sensitivity of the measurements of the Keap1-Nrf2 interaction in live cells.
关键词： FRET,live cell imaging,fluorescence lifetime,FLIM,sfGFP,protein-protein interaction,global binning,Keap1,Instrument Response Function,Nrf2
更新于2025-11-21 11:08:12
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[Methods in Molecular Biology] Plant Long Non-Coding RNAs Volume 1933 (Methods and Protocols) || Trimolecular Fluorescence Complementation (TriFC) Assay for Visualization of RNA-Protein Interaction in Plants
摘要： RNA-protein interactions play important roles in various eukaryotic biological processes. Molecular imaging of subcellular localization of RNA-protein complexes in plants is critical for understanding these interactions. However, methods to image RNA-protein interactions in living plants have not yet been developed until now. Recently, we have developed a trimolecular fluorescence complementation (TriFC) system for in vivo visualization of RNA-protein interaction by transient expression in tobacco leaves. In this method, we combined conventional bimolecular fluorescence complementation (BiFC) system with the MS2 system (phage MS2 coat protein [MCP] and its binding RNA sequence [MS2 sequence]) to tag lncRNA. Target RNA is tagged with 6xMS2, and MCP and RNA-binding protein are fused with YFP fragments. DNA constructs encoding such fusion RNA and proteins are infiltrated into tobacco leaves with Agrobacterium suspensions. RNA-protein interaction in vivo is observed by confocal microscopy.
关键词： RNA-protein interaction,Long noncoding RNA,TriFC,Tobacco transient expression,In vivo visualization
更新于2025-11-21 11:08:12
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Facile Construction of Defect-rich Rhenium Disulfide/Graphite Carbon Nitride Heterojunction via Electrostatic Assembly for fast Charge Separation and Photoactivity Enhancement
摘要： Graphite carbon nitride (CN) is one of the most researched visible light photocatalysts, but it still cannot be used practically because of its low photoactivity resulting mainly from rapid photogenerated charge recombination. To accelerate charge separation, CN was herein electrostatically assembled with ReS2, a two-dimensional semiconductor to construct heterojunction for the first time. The electrostatic and coordination interactions between CN and defect-rich ReS2 make them close contact to form heterojunctions. The ReS2/CN heterojunction exhibits higher photocatalytic performance in pollutant degradation owing to faster generation of reactive oxygen species than CN, as well as increased visible and near-infrared light absorption because of strong photoabsorption of defect-rich ReS2. The accelerated reactive oxygen species generation for the heterojunction arises from accelerated charge separation, especially fast transfer of holes from CN to ReS2 in assistance of interfacial electric field and great valance-band edge difference. This work provides a novel CN-based heterojunction for photoactivity improvement and illustrates significance of electrostatic attraction in fabricating heterojunctions.
关键词： electrostatic interaction,photocatalytic,rhenium disulfide,graphite carbon nitride,charge separation
更新于2025-11-21 11:03:13
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Influence of pretreatment on surface interaction between Cu and anatase-TiO2 in the simultaneous photoremediation of nitrate and oxalic acid
摘要： Copper-promoted anatase-type TiO2 photocatalysts (2.5 wt% Cu) were prepared by wet impregnation onto TiO2 which was pre-calcined at 600°C and the other not subjected to any thermal pre-treatment. In the latter case, the material was inactive for the photo-reduction of nitrate whereas 600°C pre-calcined TiO2 yielded a material which was active for the same reaction. The surface properties of the materials were determined by BET Surface area, SEM TEM, XRD, XPS, TPR, UV-Visible diffuse reflectance, DTA, N2O pulsed chemisorption and FTIR studies. The BET and XRD and DTA showed that pre-calcination of TiO2 stabilised the support, but coalescence of particles was observed in TiO2 that was not subjected to any thermal pre-treatment as evidenced by crystallite growth. Similarly, XPS, FTIR and TPR proved the formation of Cu2O particles on the surface of pre-calcined TiO2. On the other hand, the absence of pre-calcination step resulted in interring of Cu species within the grown anatase crystallites that hindered their proper distribution over TiO2, helped in its inactiveness in the photoreduction of nitrate. However, the prepared material using pre-calcined TiO2 showed the overall nitrate and oxalic acid removal efficiency of 31 and 70% with N2 and NH4+ selectivity of 44.9 and 55.1 %, respectively. The results provide insight into the significance of activity-structure relation, inferring that the two surfaces were chemically not similar. Thus, as even supported by adsorption experiment, difference in photocatalytic behaviour amongst the prepared materials was a function of crystallinity, particle size, absence of surface defect and high energy sites.
关键词： Nitrate,photocatalyst,photoremediation,metal oxide-support interaction,oxalic acid
更新于2025-11-19 16:56:35
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Directed Nanoscale Self-assembly of Natural Photosystems on Nitrogen-doped Carbon Nanotubes for Solar Energy Harvesting
摘要： Natural photosystems (PSs) have received much attention as a biological solar energy harvester because of their high quantum efficiency for energy transfer. However, the PSs hybridized with solid electrodes exhibit low light-harvesting efficiencies because of poor interface properties and random orientations of PSs, all of which interfere with efficient charge extraction and transfer. Herein, we report the linker-free, oriented self-assembly of natural PSs with nitrogen-doped carbon nanotubes (NCNTs) via electrostatic interaction. Protonated nitrogen-doped sites on the NCNTs facilitate spontaneous immobilization of the negatively charged stroma side of PSs, which provides a favorable orientation for electron transfer without electrically insulating polymer linkers. The resulting PS/NCNT hybrids exhibit a photocurrent density of 1.25 ± 0.08 μA cm-2, which is much higher than that of PS/CNT hybrids stabilized with polyethylenimine (0.60 ± 0.01 μA cm-2) and sodium dodecyl sulfate (0.14 ± 0.01 μA cm-2), respectively. This work emphasizes the importance of the linker-free assembly of PSs into well-oriented hybrid structures to construct an efficient light-harvesting electrode.
关键词： Light-harvesting,Electrostatic interaction,Photosystems,Nitrogen-doped carbon nanotubes,Self-assembly
更新于2025-11-14 15:29:11
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Dendritic PAMAM polymers for strong perovskite intergranular interaction enhancing power conversion efficiency and stability of perovskite solar cells
摘要： The modification of perovskite intergranular perovskite/perovskite interface plays a critical role for power conversion efficiency (PCE) and stability of perovskite solar cells (PSCs). In this work, polyamidoamine (PAMAM) dendrimers are utilized as the dendritic crystallization framework templating the perovskite-crystallizing process. The interactions at the perovskite intergranular interface are considerably strengthened at an ambient environment with dendritic PAMAMs crosslinking the perovskite grains. Consequently, the perovskite morphology is remarkably improved by suppressing the grain/grain-aggregate boundaries for the pinhole removal, which produces a compact, uniform and non-pinhole perovskite film. Finally, the strengthened interfacial interactions dramatically enhance the PCE value of unencapsulated PSCs about 42.6% at an ambient condition. Besides, the unencapsulated PAMAM-modified device can keep 73% of initial PCE value in 400 h while the control device decays to 5% of initial PCE value in 50 h. These results reveal that dendritic polymers might remarkably improve the PCE value and the stability of PSCs. This work provides a new molecular design guideline to effectively regulate the perovskite intergranular interfacial interactions.
关键词： Grain boundary,Interfacial interaction,Intergranular interface,Dendrimer,Perovskite solar cell
更新于2025-11-14 15:27:09
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Silicon Corrosion in Neutral Media: The Influence of Confined Geometries and Crevice Corrosion in Simulated Physiological Solutions
摘要： Silicon (Si) based implantable components are widely used to restore functionalities in the human body. However, there have been reported instances of Si corroding after only a few years of implantation. A key parameter often overlooked when assessing Si stability in-vitro, is the added constricting geometries introduced through in-vivo implantation. The influence of crevices and confined solutions on the stability of Si is presented in this study, considering two simulated physiological solutions: 0.01 M phosphate buffered saline (PBS) and HyClone Wear Test Fluid (WTF). It was found that Si is highly vulnerable to corrosion in confined/crevice conditions. High pitting corrosion susceptibility is found in a crevice, whereas a dissolution rate of ca. 3.6 nm/h at body temperature occurred due to local alkalization within a confined cathodic area. The corrosion rates could be increased by elevating the temperature and yielded linear Arrhenius relations, with activation energies of 106 KJ/mol in 0.01 M PBS and 109 KJ/mol in HyClone WTF, corresponding to a phosphorous-silicon interaction mechanism. Phosphorous species favored corrosion and contributed to enhanced Si dissolution, while chlorides were not so influential, and applied anodic potential induced pseudo-passivation. These results highlight the importance geometrical configurations can have on a material’s surface stability.
关键词： Silicon,Confined geometries,Corrosion,Physiological solutions,Implantable devices,Phosphorous-silicon interaction,Crevice
更新于2025-11-14 15:19:41