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Quantum yield

Milene N O Moritz, Joyce L S Gonçalves, Irwin A P Linares, Janice R Perussi, Kleber T de Oliveira
An amphiphilic chlorin derivative (CHL-T) was prepared from methylpheophorbide a (CHL) and 2-Amino-2-(hydroxymethyl)-1,3-propanediol (TRISMA(®)). The new chlorin was compared to other dyes (CHL and Hypericin) in relation to photophysical and photobiological activities in tumor and non-tumor cell lines. Cytotoxicity and cell death target were determined to evaluate the CHL-T efficiency, comparing to the precursor CHL and to the well-known dye hypericin (HY). All of the studied compounds exhibited absorption bands in the therapeutic window and presented a small fluorescence quantum yield compared to the reference dye (rhodamine B)...
October 18, 2016: Photodiagnosis and Photodynamic Therapy
Aurélie Stallivieri, Ludovic Colombeau, Gulim Jetpisbayeva, Albert Moussaron, Bauyrzhan Myrzakhmetov, Philippe Arnoux, Samir Acherar, Régis Vanderesse, Céline Frochot
Recent researches in photodynamic therapy have focused on novel techniques to enhance tumour targeting of anticancer drugs and photosensitizers. Coupling a photosensitizer with folic acid could allow more effective targeting of folate receptors which are over-expressed on the surface of many tumour cells. In this study, different folic acid-OEG-conjugated photosensitizers were synthesized, characterized and their photophysical properties were evaluated. The introduction of an OEG does not significantly improve the hydrophilicity of the FA-porphyrin...
October 10, 2016: Bioorganic & Medicinal Chemistry
Sohini Sinha, Anuja Plavuvalapil Kumaran, Debasish Mishra, Priyankar Paira
Recently a choice of fluorescent bioimaging probes have been developed as medical diagnostic tools. Herein, we have introduced a series of coumarin-based target specific probes for cancer theranostic application which play a dual role in the field of both diagnosis and therapy. A fluorogenic version of 1,3-dipolar cycloaddition between azides and alkynes (DBCO) has been introduced to develop the triazolylcoumarin based fluorescent scaffolds. These scaffolds were screened for their anticancer activity against breast cancer (MCF7) and human epitheloid cervix carcinoma (HeLa) cell line...
October 1, 2016: Bioorganic & Medicinal Chemistry Letters
Yanhong Ma, Ziang Zhang, Yueling Xu, Ming Ma, Bo Chen, Lin Wei, Lehui Xiao
In this work, we demonstrated a convenient and green strategy for the synthesis of bright and water-soluble carbon dots (CDs) by carbonizing sodium citrate and glutathione together in a hydrothermal method for the first time. Without post surface modification, the as-synthesized CDs display fluorescence quantum yield (QY) as high as 21.03% and show superior stability not only in concentrated salt solutions but also in neutral and alkaline media. The probe exhibits selective and sensitive recognition capability towards mercury ion (Hg(2+)) in aqueous solution...
December 1, 2016: Talanta
Jiamian Wang, Jie Song, Xiuyun Wang, Shuo Wu, Yanqiu Zhao, Pinchen Luo, Changgong Meng
A label-free ratiometric fluorescence aptasensor has been developed for the rapid and sensitive detection of cocaine in complex biofluids. The fluorescent aptasensor is composed of a non-labeled GC-38 cocaine aptamer which serves as a basic sensing unit and two fluorophores, 2-amino-5,6,7-trimethyl-1,8-naphthyridine (ATMND) and SYBR Green I (SGI) which serves as a signal reporter and a build-in reference, respectively. The detection principle is based on a specific cocaine mediated ATMND displacement reaction and the corresponding change in the fluorescence ratio of ATMND to SGI...
December 1, 2016: Talanta
Hao Zhu, Jiangli Fan, Huiying Mu, Tao Zhu, Zhen Zhang, Jianjun Du, Xiaojun Peng
Polarity-sensitive fluorescent probes are powerful chemical tools for studying biomolecular structures and activities both in vitro and in vivo. However, the lack of "off-on" polarity-sensing probes has limited the accurate monitoring of biological processes that involve an increase in local hydrophilicity. Here, we design and synthesize a series of "off-on" polarity-sensitive fluorescent probes BP series consisting of the difluoroboron dippyomethene (BODIPY) fluorophore connected to a quaternary ammonium moiety via different carbon linkers...
October 21, 2016: Scientific Reports
Fabien Brieuc, Yael Bronstein, Hichem Dammak, Philippe Depondt, Fabio Finocchi, Marc Hayoun
The quantum thermal bath (QTB) has been presented as an alternative to path-integral based methods to introduce nuclear quantum effects in molecular dynamics simulations. The method has proved to be efficient, yielding accurate results for various systems. However, the QTB method is prone to zero-point energy leakage (ZPEL) in highly anharmonic systems. This is a well known problem in methods based on classical trajectories where part of the energy of the high frequency modes is transferred to the low frequency modes leading to a wrong energy distribution...
October 21, 2016: Journal of Chemical Theory and Computation
Ning-Jiu Zhao, Yu-Wei Wang, Qian Liu, Zi-Hong Lin, Ran Liang, Li-Min Fu, Xi-Cheng Ai, Zhishan Bo, Jian-Ping Zhang
A pair of 9-arylidene-9H-fluorene and benzothiadiazole based, low-bandgap copolymers differing merely in the para or meta substitution of alkoxy groups to the arylidene linkages, i.e. p-PAFDTBT and m-PAFDTBT respectively, were comparatively investigated by using morphological characterization, ultrafast spectroscopy and quantum chemical calculations. Despite the subtle difference in the alkoxy substitution patterns, p-PAFDTBT molecules in photoactive films were shown to have a higher degree of crystallinity owing to the relatively less rotational torsion of the arylidene linkages...
October 21, 2016: Nanoscale
Sahishna Phaniraj, Zhe Gao, Digamber Rane, Blake R Peterson
The endoplasmic reticulum (ER) of eukaryotic cells plays critical roles in the processing of secreted and transmembrane proteins. Defects in these functions are associated with a wide range of pathologies. To image this organelle, cells are often treated with fluorescent ER-Tracker dyes. Although these compounds are selective, existing red fluorescent probes of the ER are costly glibenclamide derivatives that inhibit ER-associated sulphonylurea receptors. To provide simpler and more cost-effective red fluorescent probes of the ER, we synthesized amino analogues of the fluorophore resorufin...
December 2016: Dyes and Pigments: An International Journal
Yuma Hakoda, Masatoshi Aoyagi, Ken-Ichi Irisawa, Shin-Ichiro Kato, Yosuke Nakamura, Minoru Yamaji
Phenanthrenes substituted with trimethylsilylethynyl and phenylethynyl groups were photochemically prepared, and their photophysical properties were systematically investigated based on measurements of fluorescence quantum yields, lifetimes, and transient absorption. Introducing ethynyl groups into the phenanthrene skeleton caused an increase in the fluorescence quantum yields compared to that of phenanthrene. The quantum yields and rates of fluorescence were dependent on the substituting position(s) and the terminating group for the C-C triple bond...
October 20, 2016: Photochemical & Photobiological Sciences
Yiling Zhong, Bin Song, Fei Peng, Yanyan Wu, Sicong Wu, Yuanyuan Su, Yao He
Herein, we demonstrate that at room temperature (20-25 °C) and under atmospheric pressure, small-sized (∼3.1 nm) SiNPs can be rapidly formed in aqueous phase within 60 min, with high photoluminescence quantum yield (PLQY) of ∼50%. This approach is readily scalable and could potentially be used to produce high-quality SiNPs at an industrial level.
October 20, 2016: Chemical Communications: Chem Comm
Yongming Guo, Lianfeng Zhang, Fengpu Cao, Yumin Leng
A facile, simple and low-cost approach for synthesizing highly fluorescent carbon quantum dots (CQDs) from thermal treatment of sustainable hair has been developed. The resultant CQDs exhibited strong blue emission with a quantum yield of 10.75%, excellent photostability and high stability in high salt conditions. As the fluorescence of CQDs can be efficiently quenched by Hg(2+), the CQDs can be constructed as a nanosensor for Hg(2+) with good sensitivity and selectivity. And as low as 10 nM Hg(2+) can be successfully detected...
October 20, 2016: Scientific Reports
Yue Lu, Junsi Wang, Niamh McGoldrick, Xiaoneng Cui, Jianzhang Zhao, Colin Caverly, Brendan Twamley, Gearoid M Ó Máille, Bryan Irwin, Robert Conway-Kenny, Sylvia M Draper
"Chemistry-on-the-complex" synthetic methods have allowed the selective addition of 1-ethynylpyrene appendages to the 3-, 5-, 3,8- and 5,6-positions of Ir(III) -coordinated 1,10-phenanthroline via Sonogashira cross-coupling. The resulting suite of complexes has given rise to the first rationalization of their absorption and emission properties as a function of the number and position of the pyrene moieties. Strong absorption in the visible region (e.g. 3,8-substituted Ir-3: λabs =481 nm, ϵ=52 400 m(-1)  cm(-1) ) and long-lived triplet excited states (e...
October 20, 2016: Angewandte Chemie
Justin A Lemkul, Alexander D MacKerell
Mg2+ ions are important in biological systems, particularly in stabilizing compact RNA folds. Mg2+ is strongly polarizing, and representing its interactions in heterogeneous environments is a challenge for empirical force field development. To date, the most commonly used force fields in molecular dynamics simulations utilize a pairwise-additive approximation for electrostatic interactions, which cannot account for the significant polarization response in systems containing Mg2+. In the present work, we refine the interactions of Mg2+ with water, Cl- ions, and nucleic acid moieties using a polarizable force field based on the classical Drude oscillator model...
October 19, 2016: Journal of Physical Chemistry. B
Xiaoyu Zhang, Chun Sun, Yu Zhang, Hua Wu, Changyin Ji, Yahui Chuai, Peng Wang, Shanpeng Wen, Chunfeng Zhang, William W Yu
The high photoluminescence efficiency, high color purity, and easy tunable bandgap make inorganic perovskite nanocrystals very attractive in luminescent display applications. Here, we report a color-saturated, red light-emitting diode (LED) using an inverted organic/inorganic hybrid structure and perovskite nanocrystals. We demonstrated that through a simple post treatment to the perovskite nanocrystals with polyethylenimine, the surface defects of the perovskite nanocrystals could be well passivated, leading to great enhancements on their absolute photoluminescence quantum yield and photoluminescence lifetime...
October 19, 2016: Journal of Physical Chemistry Letters
Bingjiang Zhou, Yunzheng Li, Guangle Niu, Minhuan Lan, Qingyan Jia, Qionglin Liang
Given their easy structural modification and good biocompatibility advantages, near-infrared (NIR) organic dyes with a large molar extinction coefficient while a super-low fluorescence quantum yield show considerable potential application in photothermal therapy (PTT). Herein, a new NIR-absorbing asymmetric cyanine dye, namely, RC, is designed and synthesized via the hybrid of rhodamine and hemicyanine derivatives. RC-BSA nanoparticles (NPs) are fabricated by using the bovine serum albumin (BSA) matrix. The NPs exhibit a strong NIR absorption peak at ~868 nm and 28...
October 19, 2016: ACS Applied Materials & Interfaces
Yohei Okada, Masae Sugai, Kazuhiro Chiba
Fluorophores with emission wavelengths that shift depending on their hydrogen-bonding microenvironment in water would be fascinating tools for the study of biological events. Herein, we describe the design and synthesis of a series of water-soluble solvatochromic fluorophores, 2,5-bis(oligoethylene glycol)oxybenzaldehydes (8-11) and 2,5-bis(oligoethylene glycol)oxy-1,4-dibenzaldehydes (14-17), based on a push-pull strategy. Unlike typical examples in this class of fluorophores, the fluorescence properties of these compounds are independent of solvent polarity and become fluorescent upon intermolecular hydrogen-bonding, exhibiting high quantum yields (up to φ = 0...
October 18, 2016: Journal of Organic Chemistry
Wen-Yong Lai, Cheng Cheng, Yi Jiang, Cheng-Fang Liu, Jian-Dong Zhang, Wei Huang
A novel set of star-shaped polycyclic aromatic hydrocarbons (PAHs) based on naphthalenes-fused truxenes, named as TrNaCn (n = 1-4), were synthesized and characterized. Oxidative cyclodehydrogenation was carried out following the microwave-assisted six-fold Suzuki coupling reaction. It is worthwhile to mention that multiple dehydrocyclization samples can be isolated effectively in one reaction, suggesting that the oxidative cyclodehydrogenation was a stepwise ring-closed process. Thermal, optical, and electrochemical properties, and self-assembly behaviors of the resulting oxidized samples were investigated to understand the impact of the ring-fused process on the properties of star-shaped PAHs...
October 18, 2016: Chemistry, An Asian Journal
Masaaki Mitsui, Koji Higashi, Yohei Hirumi, Kenji Kobayashi
The effects of supramolecular encapsulation on the photophysics and photostability of a highly fluorescent dimeric derivative of 2,6-diacetoxy-9,10-bis(arylethynyl)anthracene (G2) were investigated by single-molecule fluorescence spectroscopy (SMFS). The fluorescence properties of free-G2 and its self-assembled boronic ester encapsulation complex, G2@(Cap)2, were compared in solution and a glassy polymer film. The fluorescence spectral characteristics and theoretical calculations suggest that the environment affects the excited-state conformation and subsequent fluorescence emission of G2@(Cap)2...
October 18, 2016: Journal of Physical Chemistry. A
Atanu Acharya, Alexey M Bogdanov, Bella L Grigorenko, Ksenia B Bravaya, Alexander V Nemukhin, Konstantin A Lukyanov, Anna I Krylov
Photoinduced reactions play an important role in the photocycle of fluorescent proteins from the green fluorescent protein (GFP) family. Among such processes are photoisomerization, photooxidation/photoreduction, breaking and making of covalent bonds, and excited-state proton transfer (ESPT). Many of these transformations are initiated by electron transfer (ET). The quantum yields of these processes vary significantly, from nearly 1 for ESPT to 10(-4)-10(-6) for ET. Importantly, even when quantum yields are relatively small, at the conditions of repeated illumination the overall effect is significant...
October 18, 2016: Chemical Reviews
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