- 标题
- 摘要
- 关键词
- 实验方案
- 产品
-
Fluorescence resonance energy transfer (FRET) between acriflavine and CdTe quantum dot
摘要： In this report we have studied Fluorescence Resonance Energy Transfer between Acri?avine (Acf) and Cadmium Telluride (CdTe) quantum dot. CdTe quantum dots were synthesized by hydrothermal method. Spectroscopic characterizations revealed the formation of a FRET pair consisting of Acri?avine (AcF) as donor and CdTe quantum dot as acceptor having energy transfer ef?ciency 39.5%.
关键词： Quantum dot,XRD,CdTe,FRET
更新于2025-09-23 15:21:01
-
Global Folding of a Na+-Specific DNAzyme Studied by FRET
摘要： Recently a few RNA-cleaving DNAzymes have been isolated with excellent specificity for Na+, and some of them contain a Na+ binding aptamer. This metal recognition mechanism is different from most previously reported DNAzymes. Previous studies using 2-aminopurine (2AP) as a probe have indicated interesting local folding by Na+. In this work, fluorescence resonance energy transfer (FRET) was used to probe the global folding of the Ce13d DNAzyme, one of the Na+-specific DNAzymes. FRET pairs were at different locations yielding a total of five constructs to probe its three-way junction structure with a large loop. With end-labelled DNAzymes, the global structure appears quite rigid with little folding by adding up to 200 mM monovalent metal ions, although some minor differences were observed between Li+, Na+ and K+. This lack of large conformational change is also consistent with CD spectroscopy data. The loop was then labelled with an internal TMR fluorophore at the G14 position, and its cleavage activity was partially retained. A clear Na+-dependent folding was observed with spectral crossover. From a biosensing standpoint, global folding based sensors are unlikely to work due to the overall rigid structure of the DNAzyme. Therefore, the best way using this DNAzyme to discriminate Na+ from K+ is based on cleavage activity, followed by probing local folding, while global folding is the least effective for metal discrimination.
关键词： Na+,aptamer,FRET,global folding,DNAzyme
更新于2025-09-23 15:21:01
-
Build Your Own Microscope: Step-By-Step Guide for Building a Prism-Based TIRF Microscope
摘要： Prism-based total internal re?ection ?uorescence (pTIRF) microscopy is one of the most widely used techniques for the single molecule analysis of a vast range of samples including biomolecules, nanostructures, and cells, to name a few. It allows for excitation of surface bound molecules/particles/quantum dots via evanescent ?eld of a con?ned region of space, which is bene?cial not only for single molecule detection but also for analysis of single molecule dynamics and for acquiring kinetics data. However, there is neither a commercial microscope available for purchase nor a detailed guide dedicated for building this microscope. Thus far, pTIRF microscopes are custom-built with the use of a commercially available inverted microscope, which requires high level of expertise in selecting and handling sophisticated instrument-parts. To directly address this technology gap, here we describe a step-by-step guide on how to build and characterize a pTIRF microscope for in vitro single-molecule imaging, nanostructure analysis and other life sciences research.
关键词： single-molecule detection,single-molecule FRET,?uorescence microscope,pTIRF
更新于2025-09-23 15:21:01
-
Chlorin e6a??CdSe/ZnS Quantum Dots Nanocomposites as Efficient Singlet Oxygen Generator
摘要： A new approach to the formation of colloidal nanocomposites based on CdSe/ZnS quantum dots and monomeric form of Chlorin e6 is suggested. We demonstrate that FRET with efficiency close to theoretical prediction can be realized in the nanocomposites, and it leads to twofold enhancement of singlet oxygen generation in comparison with the same amount of free Chlorin e6.
关键词： quantum dots,Chlorin e6,FRET,nanocomposites,photosensitizers,singlet oxygen
更新于2025-09-23 15:19:57
-
Long Range Energy Transfer in Self-Assembled Stacks of Semiconducting Nanoplatelets
摘要： Fluorescent emitters like ions, dye molecules or semiconductor nanoparticles are widely used in opto-electronic devices, usually within densely-packed layers. Their luminescence properties can then be very different from when they are isolated, because of short-range interparticle interactions such as F?rster resonant energy transfer (FRET). Understanding these interactions is crucial to mitigate FRET-related losses and could also lead to new energy transfer strategies. Exciton migration by FRET hopping between consecutive neighbor fluorophores has been evidenced in various systems but was generally limited to distances of tens of nanometers and involved only a few emitters. Here we image self-assembled linear chains of CdSe nanoplatelets (colloidal quantum wells) and demonstrate exciton migration over 500-nm distances, corresponding to FRET hopping over 90 platelets. By comparing a diffusion-equation model to our experimental data, we measure a (1.5 ps)-1 FRET rate, much faster than all decay mechanisms, so that strong FRET-mediated collective photophysical effects can be expected.
关键词： nanoplatelets,exciton transfer,self-assembly,fluorescence microscopy,FRET
更新于2025-09-23 15:19:57
-
Off-Resonance Control and All-Optical Switching: Expanded Dimensions in Nonlinear Optics
摘要： The theory of non-resonant optical processes with intrinsic optical nonlinearity, such as harmonic generation, has been widely understood since the advent of the laser. In general, such effects involve multiphoton interactions that change the population of each input optical mode or modes. However, nonlinear effects can also arise through the input of an off-resonant laser beam that itself emerges unchanged. Many such effects have been largely overlooked. Using a quantum electrodynamical framework, this review provides detail on such optically nonlinear mechanisms that allow for a controlled increase or decrease in the intensity of linear absorption and fluorescence and in the efficiency of resonance energy transfer. The rate modifications responsible for these effects were achieved by the simultaneous application of an off-resonant beam with a moderate intensity, acting in a sense as an optical catalyst, conferring a new dimension of optical nonlinearity upon photoactive materials. It is shown that, in certain configurations, these mechanisms provide the basis for all-optical switching, i.e., the control of light-by-light, including an optical transistor scheme. The conclusion outlines other recently proposed all-optical switching systems.
关键词： absorption,nonlinear optics,all-optical switch,resonance energy transfer,fluorescence,FRET,optical transistor,multiphoton process,laser action,second harmonic generation
更新于2025-09-23 15:19:57
-
Long-Range Single-Molecule F??rster Resonance Energy Transfer between Alexa Dyes in Zero-Mode Waveguides
摘要： Zero-mode waveguide (ZMW) nano-apertures milled in metal films were proposed to improve the F?rster resonance energy transfer (FRET) efficiency and enable single-molecule FRET detection beyond the 10 nm barrier, overcoming the restrictions of diffraction-limited detection in a homogeneous medium. However, the earlier ZMW demonstrations were limited to the Atto 550?Atto 647N fluorophore pair, asking the question whether the FRET enhancement observation was an artifact related to this specific set of fluorescent dyes. Here, we use Alexa Fluor 546 and Alexa Fluor 647 to investigate single-molecule FRET at large donor?acceptor separations exceeding 10 nm inside ZMWs. These Alexa fluorescent dyes feature a markedly different chemical structure, surface charge, and hydrophobicity as compared to their Atto counterparts. Our single molecule data on Alexa 546?Alexa 647 demonstrate enhanced FRET efficiencies at large separations exceeding 10 nm, extending the spatial range available for FRET and confirming the earlier conclusions. By showing that the FRET enhancement inside a ZMW does not depend on the set of fluorescent dyes, this report is an important step to establish the relevance of ZMWs to extend the sensitivity and detection range of FRET, while preserving its ability to work on regular fluorescent dye pairs.
关键词： single-molecule,nanophotonics,FRET,Alexa Fluor,Zero-mode waveguide
更新于2025-09-23 15:19:57
-
How quantum dots aggregation enhances F??rster??Resonant Energy Transfer
摘要： As luminescent quantum dots (QDs) are known to aggregate themselves through their chemical activation by carbodiimide chemistry and their functionalization with biotin molecules, we investigate both effects on the fluorescence properties of CdTe QDs and their impact on F?rster Resonant Energy Transfer (FRET) occurring with fluorescent streptavidin molecules (FA). First, the QDs fluorescence spectrum undergoes significant changes during the activation step which are explained thanks to an original analytical model based on QDs intra-aggregate screening and inter-QDs FRET. We also highlight the strong influence of biotin in solution on FRET efficiency, and define the experimental conditions maximizing the FRET. Finally, a free-QD-based system and an aggregated-QD-based system are studied in order to compare their detection threshold. The results show a minimum concentration limit of 80 nM in FA for the former while it is equal to 5 nM for the latter, favouring monitored aggregation in the design of QDs-based biosensors.
关键词： fluorescence spectroscopy,biosensors,FRET,quantum dots,Biochemical functionalization
更新于2025-09-23 15:19:57
-
Automated <i>E-FRET</i> microscope for dynamical live-cell FRET imaging
摘要： Acceptor-sensitized 3-cube fluorescence resonance energy transfer (FRET) imaging (also termed as E-FRET imaging) is a popular fluorescence intensity-based FRET quantification method. Here, an automated E-FRET microscope with user-friendly interfaces was set up for dynamical online quantitative live-cell FRET imaging. This microscope reduces the time of a quantitative E-FRET imaging from 12 to 3 seconds. After locating cells, calibration of the microscope and E-FRET imaging of the cells can be performed automatically by clicking “Capture” button on interfaces. E-FRET imaging was performed on the microscope for living cells expressing different FRET tandem constructs. Dynamical E-FRET imaging on the microscope for live cells co-expressing CFP-Bax and YFP-Bax treated by staurosporine (STS) revealed three Bax redistribution stages: Bax translocation from cytosol to mitochondria within 10 minutes, membrane insertion with conformational change on mitochondrial membrane within about 30 minutes, and subsequent oligomerization within about 10 minutes. Because of excellent user-friendly interface and stability, the automated E-FRET microscope is a convenient tool for quantitative FRET imaging of living cell.
关键词： FRET,biochemical signal transduction,system design,microscope
更新于2025-09-19 17:15:36
-
Smallest near-infrared fluorescent protein evolved from cyanobacteriochrome as versatile tag for spectral multiplexing
摘要： From a single domain of cyanobacteriochrome (CBCR) we developed a near-infrared (NIR) fluorescent protein (FP), termed miRFP670nano, with excitation at 645 nm and emission at 670 nm. This is the first CBCR-derived NIR FP evolved to efficiently bind endogenous biliverdin chromophore and brightly fluoresce in mammalian cells. miRFP670nano is a monomer with molecular weight of 17 kDa that is 2-fold smaller than bacterial phytochrome (BphP)-based NIR FPs and 1.6-fold smaller than GFP-like FPs. Crystal structure of the CBCR-based NIR FP with biliverdin reveals a molecular basis of its spectral and biochemical properties. Unlike BphP-derived NIR FPs, miRFP670nano is highly stable to denaturation and degradation and can be used as an internal protein tag. miRFP670nano is an effective FRET donor for red-shifted NIR FPs, enabling engineering NIR FRET biosensors spectrally compatible with GFP-like FPs and blue–green optogenetic tools. miRFP670nano unlocks a new source of diverse CBCR templates for NIR FPs.
关键词： near-infrared fluorescent protein,spectral multiplexing,cyanobacteriochrome,FRET biosensors,biliverdin,optogenetics
更新于2025-09-19 17:15:36