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Fluorescence Lifetime

Yahui Li, Hui Jia, Shaorong Chen, Jinshou Tian, Lingliang Liang, Fenfang Yuan, Hongqi Yu, David Day-Uei Li
Qualitative and quantitative measurements of complex flows demand for fast single-shot fluorescence lifetime imaging (FLI) technology with high precision. A method, single-shot time-gated fluorescence lifetime imaging using three-frame images (TFI-TGFLI), is presented. To our knowledge, it is the first work to combine a three-gate rapid lifetime determination (RLD) scheme and a four-channel framing camera to achieve this goal. Different from previously proposed two-gate RLD schemes, TFI-TGFLI can provide a wider lifetime range 0...
July 9, 2018: Optics Express
Elham Abdollahi, Gisela Taucher-Scholz, Burkhard Jakob
In recent years several approaches have been developed to address the chromatin status and its changes in eukaryotic cells under different conditions-but only few are applicable in living cells. Fluorescence lifetime imaging microscopy (FLIM) is a functional tool that can be used for the inspection of the molecular environment of fluorophores in living cells. Here, we present the use of single organic minor groove DNA binder dyes in FLIM for measuring chromatin changes following modulation of chromatin structure in living cells...
August 14, 2018: International Journal of Molecular Sciences
Eduarda Fernandes, Telma B Soares, Hugo Gonçalves, Marlene Lúcio
The goal of this study is to provide tools to minimize trial-and-error in the development of novel lipid-based nanotherapeutics, in favor of a rational design process. For this purpose, we present case-study examples of biophysical assays that help addressing issues of lipid-based nanotherapeutics' profiling and assist in the design of lipid nanocarriers for therapeutic usage. The assays presented are rooted in spectroscopic methods (steady-state and time-resolved fluorescence; UV-Vis derivative spectroscopy; fluorescence anisotropy and fluorescence lifetime image microscopy) and allow accessing physical-chemical interactions between drugs and lipid nanocarriers, as well as studying interactions between lipid-based nanotherapeutics and membranes and/or proteins, as this is a key factor in predicting their therapeutic and off target effects...
2018: Frontiers in Chemistry
Woohyun Jung, Byung Joo Kong, Seongjin Hong, Taeoh Kim, Kyunghwan Oh
We experimentally demonstrated a green liquid laser at the wavelength of 570 nm, utilizing the optical gain of vitamin B2 in a highly polar organic solvent, and proposed an efficient method to enhance its lasing efficiency by adding DNA-lipid complex (DNA-CTMA) in the solution. Optical properties of vitamin B2 in the hexafluoro-2-propanol solvents were investigated by adding various amounts of DNA-CTMA in terms of the UV-visible absorbance, the visible emission, and the fluorescence lifetime. A Fabry-Perot cavity was built to obtain the laser oscillation at 570 nm using a pulsed pump source at the wavelength of 450 nm, 5 ns pulse duration, and 10 Hz repetition rate...
August 15, 2018: Optics Letters
Ju-Hung Chao, Wenbin Zhu, Chang-Jiang Chen, Yun-Goo Lee, Annan Shang, Shizhuo Yin, Robert C Hoffman
We report a new type of photoconductive semiconductor switch (PCSS), consisting of a semi-insulating gallium arsenic (GaAs) substrate and a front-bonded ruby crystal. The 532 nm laser pulses from an Nd-YAG laser incident on the front surface of the ruby crystal. A portion of the laser pulse passes through the crystal and reaches the GaAs substrate, and the remaining portion of the laser pulse is absorbed by the ruby crystal. This results in the emission of 694 nm fluorescent light. Furthermore, a portion of emitted fluorescent light also reaches the GaAs substrate...
August 15, 2018: Optics Letters
Akash Gulyani, Nilanjan Dey, Santanu Bhattacharya
Despite decades-long extensive research, probes that provide a comprehensive description of the lipid membrane microenvironment are still lacking. We report here a 'smart' pyrene-terpyridine probe for multiparametric sensing of lipid membranes; wherein the complexity of the local microenvironment can be described by distinct features of the probe fluorescence. The self-assembly of the probe molecules in phospholipid bilayers is sensitive to membrane order and phase state. The self-assembled probes show a unique emission, influenced by dye-dye interactions and excited state charge transfer...
August 14, 2018: Chemistry: a European Journal
Changli Zhang, Minsheng Liu, Shaoxian Liu, Hui Yang, Qiang Zhao, Zhipeng Liu, Weijiang He
Phosphorescence lifetime Zn2+ imaging possesses the advantage over normal fluorescence imaging in offering the more accurate temporal-spatial Zn2+ information. Herein, we report a new phosphorescent cyclometalated Ir(III) complex with a Zn2+ -chelator bearing 1,10-phenanthrolin acting as ancillary ligand, Zin-IrDPA, which displays the specific Zn2+ -induced enhancement of phosphorescence and phosphorescence lifetime, and the mitochondria-targeting ability. Moreover, its Zn2+ -induced phosphorescence lifetime enhancement factor is not affected by medium lipophilicity, viscosity, polarity, and especially ambient oxygen...
August 13, 2018: Inorganic Chemistry
Pablo Wessig, Dörthe Büchner, Leonard John, Monique Mertens
DBD fluorescent dyes have proven to be useful in numerous applications. In order to widen the range of biological applications we propose three different types of DBD-molecules that have been modified in such a way, that DNA interaction becomes probable. After the successful synthesis of all three compounds, we tested their fluorescent properties and their DNA binding abilities. Two out of three probes exhibit an interaction with dsDNA and a subsequent fluorescence enhancement. The determined binding constants of the two new DNA dyes are comparable to other minor groove binding dyes...
August 13, 2018: Chemistry: a European Journal
Dzmitry Melnikau, Saioa Elcoroaristizabal, Alan George Ryder
The accurate fluorescence analysis of complex, multi-fluorophore containing proteins requires the use of multi-dimensional measurement techniques. For the measurement of intrinsic fluorescence from tyrosine (Tyr) and tryptophan (Trp) one needs tunable UV excitation and for steady-state measurements like Excitation Emission Matrix (EEM) simple pulsed Xe lamps are commonly used. Unfortunately, simultaneous multi-dimensional wavelength and time resolved measurement of intrinsic protein fluorescence in the 260 to 400 nm spectral range are challenging and typically required the use of very complex tunable laser systems or multiple single excitation wavelength sources...
August 13, 2018: Methods and Applications in Fluorescence
Rijia Khatun, Koushik Majhi, Venkanna Meriga, Amit Kumar Chakraborty, Subrata Sinha
Sulfonated polyaniline (SPANI) has emerged as a promising polymer in the last few decades due to its solubility in water and relatively moderate conductivity. However, till date, literature data on the optical characterization of SPANI are very limited and preliminary in nature. In the present work, SPANI is synthesized by direct sulfonation of emeraldine salt form of polyaniline with chlorosulfonic acid in an inert solvent. Detail photophysical properties of SPANI are investigated in aqueous medium by using steady state (concentration, temperature, pH and excitation wavelength dependence) and time-resolved spectroscopic techniques...
August 13, 2018: Journal of Physical Chemistry. A
Fan Zhang, Lei Zhou, Yong Fan, Rui Wang, Xiaomin Li, Lingling Fan
Optical multiplexing benefits on-site detection, and plays an important role in fields ranging from advanced biological assays to security. However, conventional codes based on fluorescent color and intensity are limited to spectral overlap and background interference, thus restricting the number of distinguishable identities. Herein, we present a new multiplexing concept by manipulating the luminescence emission color and decay lifetimes of upconversion nanoparticles (τλ-UCNPs) separately for the first time through decently designing of the core/multi-layered structure and controlled energy relay method...
August 12, 2018: Angewandte Chemie
Lei Ma, Bart C Jongbloets, Wei-Hong Xiong, Joshua B Melander, Maozhen Qin, Tess J Lameyer, Madeleine F Harrison, Boris V Zemelman, Tianyi Mao, Haining Zhong
Neuromodulation imposes powerful control over brain function, and cAMP-dependent protein kinase (PKA) is a central downstream mediator of multiple neuromodulators. Although genetically encoded PKA sensors have been developed, single-cell imaging of PKA activity in living mice has not been established. Here, we used two-photon fluorescence lifetime imaging microscopy (2pFLIM) to visualize genetically encoded PKA sensors in response to the neuromodulators norepinephrine and dopamine. We screened available PKA sensors for 2pFLIM and further developed a variant (named tAKARα) with increased sensitivity and a broadened dynamic range...
August 7, 2018: Neuron
Premashis Manna, Sheng-Ting Hung, Srijit Mukherjee, Pia Friis, David M Simpson, Maria N Lo, Amy E Palmer, Ralph Jimenez
Green fluorescent proteins (GFP) and their blue, cyan and red counterparts offer unprecedented advantages as biological markers owing to their genetic encodability and straightforward expression in different organisms. Although significant advancements have been made towards engineering the key photo-physical properties of red fluorescent proteins (RFPs), they continue to perform sub-optimally relative to GFP variants. Advanced engineering strategies are needed for further evolution of RFPs in the pursuit of improving their photo-physics...
August 10, 2018: Integrative Biology: Quantitative Biosciences From Nano to Macro
Nguyen Van Nghia, Saibal Jana, Surendran Sujith, Ji Yeon Ryu, Junseong Lee, Sang Uck Lee, Min Hyung Lee
A novel approach to the design of nido-carborane-based luminescent compounds that can exhibit thermally activated delayed fluorescence (TADF) is proposed. 7,8-Dicarba-nido-undecaboranes (nido-carboranes) having various 8-R groups (R = H, Me, i-Pr, Ph) are appended to the meta or para position of the phenyl ring of the dimesitylphenylborane (PhBMes2) acceptor, forming donor-acceptor compounds (nido-m1-m4 and nido-p1-p4). The bulky 8-R group and meta substitution of the nido-carborane are essential to attain a highly twisted arrangement between the donor and acceptor moieties, leading to a very small energy splitting between the singlet and triplet excited states (ΔEST < 0...
August 8, 2018: Angewandte Chemie
Fan Ni, Zece Zhu, Xiao Tong, Mingjuan Xie, Qiang Zhao, Cheng Zhong, Yang Zou, Chuluo Yang
Thermally activated delayed fluorescence (TADF) with a substantially long lifetime furnishes a new paradigm in developing probes for time-resolved imaging. Herein, a novel TADF fluorophore, namely, PXZT , with terpyridine as the acceptor and phenoxazine (PXZ) as the donor, was rationally designed and synthesized. The new compound shows typical thermally activated delayed fluorescence, aggregation-induced emission and crystallization-induced room-temperature phosphorescence (RTP). The coordination of PXZT with a zinc ion causes the quenching of the fluorescence of PXZT due to the enhanced intramolecular charge transfer of the resulting complex ZnPXZT1 ...
July 28, 2018: Chemical Science
Yang Liu, Junjun Liu, Jiayi Zhang, Xiucun Li, Fangsiyu Lin, Nan Zhou, Bai Yang, Laijin Lu
Surgical resection is recognized as a mainstay in the therapy of malignant brain tumors. In clinical practice, however, surgeons face great challenges in identifying the tumor boundaries due to the infiltrating and heterogeneous nature of neoplastic tissues. Contrast-enhanced magnetic resonance imaging (MRI) is extensively used for defining the brain tumor in clinic. Disappointingly, the commercially available (MR) contrast agents show the transient circulation lifetime and poor blood-brain barrier (BBB) permeability, which seriously hamper their abilities in tumor visualization...
July 31, 2018: ACS Omega
Sergii Kalytchuk, Yu Wang, Katerina Polakova, Radek Zbořil
Carbon dots (CDs) rank among the most promising luminescent nanomaterials for anti-counterfeiting application owing to their high fluorescence quantum yield and nontoxicity. Herein we report a novel, high-level security performance anti-counterfeiting strategy achieved by fluorescence lifetime-encoded carbon dot fluorescent inks. CD inks have identical steady-state emission properties, but they have distinctive and well-separated fluorescence lifetimes allowing authentication of security tags using exclusively fluorescence lifetime imaging (FLI)...
August 7, 2018: ACS Applied Materials & Interfaces
Ejaz Hussain, Niu Niu, Huipeng Zhou, Sohail Anjum Shahzad, Cong Yu
We report benzo[ghi]perylene (BzP) and coronene (Cron) as multimode fluorescent probes for accurate monitoring and direct visualization of monomer-micelle transitions in surfactants for the first time. The probe molecules formed self-assembled nanoparticles in an aqueous solution and displayed strong aggregation-enhanced excimer emission (AEEE). During the process of surfactant monomer-micelle transition, the probe nanoparticles dissolved, and the observation of excimer-monomer emission transition clearly indicated the formation of micelles...
August 7, 2018: Analyst
Ewa Grela, Milosz Wieczor, Rafal Luchowski, Joanna Zielińska, Angelika Barzycka, Wojciech Grudzinski, Katarzyna Nowak, Piotr Tarkowski, Jacek Czub, Wieslaw I Gruszecki
Amphotericin B is a lifesaving polyene antibiotic used in the treatment of systemic mycoses. Unfortunately, the pharmacological applicability of this drug is limited owing to its severe toxic side effects. At the same time, the lack of a well-defined mechanism of selectivity hampers the efforts to rationally design safer derivatives. As the drug primarily targets the biomembranes of both fungi and humans, new insights into the binding of amphotericin B to lipid membranes can be helpful in unveiling molecular mechanisms underlying both its pharmacological activity and toxicity...
August 6, 2018: Molecular Pharmaceutics
Xuelei Pang, Li Li, Yi Wei, Xudong Yu, Yajuan Li
Two novel luminescent organic-inorganic hybrid materials, Ln(L-SBA15)3phen (Ln = Eu, Tb), were designed and synthesized. The organic ligand phenylurea was modified by the silane coupling agent 3-(triethoxysilyl)propyl isocyanate (TESPIC) to form a precursor (L), which was covalently bonded onto a mesoporous SBA-15 backbone to form mesoporous L-SBA15 through co-hydrolysis and co-condensation reactions. 1,10-Phenanthroline monohydrate (phen) was selected as the second ligand to improve the luminescence of the final products, and the two mesoporous hybrid materials Ln(L-SBA15)3phen were obtained after the coordination reaction between the organic ligands (phen and L-SBA15) and Ln(iii) ions...
August 6, 2018: Dalton Transactions: An International Journal of Inorganic Chemistry
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