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Metal enhanced fluorescence

Ting Song, Yuan Cao, Gang Zhao, Lin Pu
Fluorescence responses of two BINOL-based diastereomeric salicylaldimines toward a variety of metal cations have been studied in methanol solution. It is revealed that both compounds show great fluorescence enhancements in the presence of Zn(2+) but not with any other metal ions. Moreover, these two diastereomers exhibit dramatically different responses toward Zn(2+) under the same conditions. That is, one can produce much stronger fluorescence enhancement also at a longer wavelength than the other. This fluorescence recognition of Zn(2+) also shows distinctive color changes under a UV lamp...
March 27, 2017: Inorganic Chemistry
Oluwasesan Adegoke, Masahiro Morita, Tatsuya Kato, Masahito Ito, Tetsuro Suzuki, Enoch Y Park
The current epidemic caused by the Zika virus (ZIKV) and the devastating effects of this virus on fetal development, which result in an increased incidence of congenital microcephaly symptoms, have prompted the World Health Organization (WHO) to declare the ZIKV a public health issue of global concern. Efficient probes that offer high detection sensitivity and specificity are urgently required to aid in the point-of-care treatment of the virus. In this study, we show that localized surface plasmon resonance (LSPR) signals from plasmonic nanoparticles (NPs) can be used to mediate the fluorescence signal from semiconductor quantum dot (Qdot) nanocrystals in a molecular beacon (MB) biosensor probe for ZIKV RNA detection...
March 22, 2017: Biosensors & Bioelectronics
Wenjie Feng, Qing Xia, Haiyan Zhou, Yun Ni, Liulin Wang, Su Jing, Lin Li, Wei Ji
A novel anthrancene-dopamine thioether L compound was designed as fluorescent probe for detecting Hg(2+) in living cells sample. L exhibits a good sensitive and selective recognition towards Hg(2+) ions in the presence of other important relevant metal ions and amino acids in HEPES solution. The addition of Hg(2+) causes a marked enhancement in the fluorescence emission intensity with the detection limit as low as 1.1×10(-6)M, combining with obvious colormetric change from colorless to pale brown. Mechanistic studies show that catechol group and sulfur atom in L all participate in the coordination with Hg(2+), though catechol group contributes mainly to chelation-enhanced fluorescence enhancement and sulfur atom to selectivity...
May 15, 2017: Talanta
Yangyang Zhao, Jing Zhao, Guiye Shan, Dongmei Yan, Yanwei Chen, Yichun Liu
It is important to control drug release and detect the distribution of drug molecules before and after release. In this work, liposome@AgAu nanocomposite is prepared for drug delivery, which not only can control drug release by near infrared laser irradiation but also can monitor drug molecules by surface enhanced Raman scattering (SERS) and fluorescence signal during the release process. The liposome@AgAu core/shell nanocomposite prepared by the galvanic replacement reaction (GRR) shows tunable localized surface plasmon resonance (LSPR) absorption peaks from visible to near-infrared region and good biocompatibility...
March 8, 2017: Colloids and Surfaces. B, Biointerfaces
Man-Jin Kim, Su-Ji Jeon, Tae Woog Kang, Jong-Min Ju, DaBin Yim, Hye-In Kim, Jung Hyun Park, Jong-Ho Kim
Modulating the dimensions and phases of transition metal dichalcogenides is of great interest to enhance their intrinsic properties or to create new physicochemical properties. Herein, we report an effective approach to synthesize 2H-WS2 quantum dots (QDs) via the dimension and phase engineering of 1T-WS2 nanosheets. The solvothermal reaction of chemically-exfoliated 1T-WS2 nanosheets in N-methyl-2-pyrrolidone (NMP) under an N2 atmosphere induced their chopping and phase transition at lower temperature to produce 2H-WS2 QDs with a high quantum yield (5...
March 20, 2017: ACS Applied Materials & Interfaces
Arturo Espinosa Ferao, Rafaela García
Azine ligands show preference for the antiperiplanar conformation, but their 2:2 ligand-metal complexes can exhibit a central N4M2 core in the most stable chair arrangement, as in the case of the model lithium complex, with the ligand displaying a synclinal conformation that is not stable in the free ligand. According to DFT calculations, complexation of Cu(2+) with bis(1-pyrenyl)azine (1) affords a C2-symmetric [1·Cu(2+)]2 species with a planar central N4Cu2 core exhibiting a weak cuprophilic interaction...
April 2017: Journal of Molecular Modeling
Yu Akimov, S Sun
In surface plasmon-polariton enhanced fluorescence, the use of spacers is simply understood to control the distance between the fluorescence dyes and metals to avoid quenching. However, the presence of a spacer layer over the metallic surface not only manipulates the quantum yield, but also affects the surface plasmon-polariton resonance, which in turn modifies the florescence excitation rate as well as the far-field radiation pattern of the emission. This study presents a systematic investigation on the spacer-controlled emission of randomly oriented emitters in the Kretschmann configuration, with the full leverage of the coupled transfer matrix, reciprocity and plane-wave decomposition methods...
March 16, 2017: Physical Chemistry Chemical Physics: PCCP
Imran Ashraf, Alexander Konrad, Heiko Lokstein, Sepideh Skandary, Michael Metzger, Joseph M Djouda, Thomas Maurer, Pierre M Adam, Alfred J Meixner, Marc Brecht
We report the temperature dependence of metal-enhanced fluorescence (MEF) of individual photosystem I (PSI) complexes from Thermosynechococcus elongatus (T. elongatus) coupled to gold nanoparticles (AuNPs). A strong temperature dependence of shape and intensity of the emission spectra is observed when PSI is coupled to AuNPs. For each temperature, the enhancement factor (EF) is calculated by comparing the intensity of individual AuNP-coupled PSI to the mean intensity of 'uncoupled' PSI. At cryogenic temperature (1...
March 13, 2017: Nanoscale
Yeonjung Lee, Seongjin Hong, Min-Seob Kim, Dahae Kim, Bo-Hyung Choi, Jin Hur, Jong Seong Khim, Kyung-Hoon Shin
Coastal areas are subjected to significant allochthonous organic matter deposits from surrounding areas; however, limited information is available on the source and delivery of this organic matter. In this study, to assess seasonal changes in the sources of organic matter in Lake Sihwa (Korea), biodegradability, fluorescence property, and stable isotopic compositions (carbon, nitrogen, and sulfur) of the organic matter were determined. Water samples were collected from the inner lake (n = 9) and inland creeks (n = 10) in five separate events, from November 2012 to October 2013...
February 28, 2017: Chemosphere
Fernando B Dias, Thomas J Penfold, Andrew P Monkman
Thermally activated delayed fluorescence (TADF) has recently emerged as one of the most attractive methods for harvesting triplet states in metal-free organic materials for application in organic light emitting diodes (OLEDs). A large number of TADF molecules have been reported in the literature with the purpose of enhancing the efficiency of OLEDs by converting non-emissive triplet states into emissive singlet states. TADF emitters are able to harvest both singlets and triplet states through fluorescence (prompt and delayed), the latter due to the thermally activated reverse intersystem crossing mechanism that allows up-conversion of low energy triplet states to the emissive singlet level...
March 9, 2017: Methods and Applications in Fluorescence
Juanjuan Ren, Ying Gu, Dongxing Zhao, Fan Zhang, Tiancai Zhang, Qihuang Gong
An evanescent optical mode existing in various nanophotonic structures always acts as a cavity mode rather than an electromagnetic vacuum in the study of cavity quantum electrodynamics (CQED). Here we show that taking the evanescent mode as an electromagnetic vacuum in which the nanocavity is located is possible through the optical mode design. The proposed evanescent vacuum enables us to enhance both the reversible photon-exciton interaction and fluorescence collection. By embedding the custom-designed plasmon nanocavity into the evanescent vacuum provided by a metallic or dielectric nanowire, the photon-exciton coupling coefficient can achieve 4...
February 17, 2017: Physical Review Letters
Daragh Byrne, Paul Duggan, Colette McDonagh
We demonstrate a method to maximise the fluorescence enhancement from a dye using gold coated diffraction gratings. Rotations about the azimuth provides a convenient approach to maximise the coupling between the grating and excitation source while achieving enhancements comparable to traditional optical configurations where the grating and in plane light vectors are parallel. This approach yields a 30 fold enhancement in the fluorescence signal over metal free substrates, while opening up the range of possible orientations and configurations suitable for fluorescence enhancement applications...
March 1, 2017: Methods and Applications in Fluorescence
Bin Wang, Qi Yang, Chao Guo, Yuxiu Sun, Lin-Hua Xie, Jian-Rong Li
Metal-organic frameworks are a class of attractive materials for fluorescent sensing. Improvement of hydrolytic stability, sensitivity, and selectivity of function is the key to advance application of fluorescent MOFs in aqueous media. In this work, two stable MOFs, [Zr6O4(OH)8(H2O)4(L(1))2] (BUT-14) and [Zr6O4(OH)8(H2O)4(L(2))2] (BUT-15), were designed and synthesized for the detection of metal ions in water. Two new ligands utilized for construction of the MOFs, namely, 5',5‴-bis(4-carboxyphenyl)-[1,1':3',1″:4″,1‴:3‴,1''''-quinquephenyl]-4,4''''-dicarboxylate (L(1)) and 4,4',4″,4‴-(4,4'-(1,4-phenylene)bis(pyridine-6,4,2-triyl))tetrabenzoate (L(2)), are structurally similar with the only difference being that the latter is functionalized by pyridine N atoms...
March 22, 2017: ACS Applied Materials & Interfaces
Anelia G Dobrikova, Ekaterina K Yotsova, Andreas Börner, Svetlana P Landjeva, Emilia L Apostolova
Тhe sensitivity to cadmium (Cd) stress of two near-isogenic wheat lines with differences at the Rht-B1 locus, Rht-B1a (tall wild type, encoding DELLA proteins) and Rht-B1c (dwarf mutant, encoding modified DELLA proteins), was investigated. The effects of 100 μM CdCl2 on plant growth, pigment content and functional activity of the photosynthetic apparatus of wheat seedlings grown on a nutrient solution were evaluated through a combination of PAM chlorophyll fluorescence, oxygen evolution, oxidation-reduction kinetics of P700 and 77 K fluorescence...
February 20, 2017: Plant Physiology and Biochemistry: PPB
Paula Ciaurriz, Fátima Fernández, Edurne Tellechea, Jose F Moran, Aaron C Asensio
The enzyme-linked immunosorbent assay (ELISA) technique is based on the specific recognition ability of the molecular structure of an antigen (epitope) by an antibody and is likely the most important diagnostic technique used today in bioscience. With this methodology, it is possible to diagnose illness, allergies, alimentary fraud, and even to detect small molecules such as toxins, pesticides, heavy metals, etc. For this reason, any procedures that improve the detection limit, sensitivity or reduce the analysis time could have an important impact in several fields...
2017: Beilstein Journal of Nanotechnology
Holger Braunschweig, Theresa Dellermann, Rian D Dewhurst, Benjamin Hupp, Thomas Kramer, James D Mattock, Jan Mies, Ashwini K Phukan, Andreas Steffen, Alfredo Vargas
Herein are reported the first π-complexes of compounds with boron-boron triple bonds with transition metals, in this case Cu(I). Three different compounds were isolated that differ in the number of copper atoms bound to the BB unit. Metalation of the B-B triple bonds causes lengthening of the B-B and B-C(NHC) bonds, as well as large upfield shifts of the (11)B NMR signals, suggesting greater orbital interactions between the boron and transition metal atoms than those observed with recently published diboryne/alkali metal cation complexes...
March 27, 2017: Journal of the American Chemical Society
Lok Nath Neupane, Gi Won Hwang, Keun-Hyeung Lee
Smart fluorescent probes of which the detection of specific target molecules can be controlled are attracting remarkable interest. A fluorescent peptidyl bioprobe (1) was rationally synthesized by conjugating tetraphenylethylene, an aggregation-induced emission (AIE) fluorophore with a peptide receptor (AspHis) that acted as hard and intermediate bases. The selective detection of 1 for specific metal ion in 100% aqueous solutions was controlled by the buffering agents with the chelate effect without the change of pH...
June 15, 2017: Biosensors & Bioelectronics
Zhong-Rui Yang, Man-Man Wang, Xue-Sheng Wang, Xue-Bo Yin
Here, we report that boric acid is used to tune the optical properties of lanthanide metal-organic frameworks (LMOFs) for dual-fluorescence emission and improves the selectivity of LMOFs for the determination of F(-) ions. The LMOFs are prepared with 5-boronoisophthalic acid (5-bop) and Eu(3+) ions as the precursors. Emission mechanism study indicates that 5-bop is excited with UV photons to produce its triplet state, which then excites Eu(3+) ions for their red emission. This is the general story of the antenna effect, but electron-deficient boric acid decreases the energy transfer efficiency from the triplet state of 5-bop to Eu(3+) ions, so dual emission from both 5-bop and Eu(3+) ions is efficiently excited at the single excitation of 275 nm...
February 7, 2017: Analytical Chemistry
Steve Ullmann, René Schnorr, Marcel Handke, Christian Laube, Bernd Abel, Jörg Matysik, Matthias Findeisen, Robert Rüger, Thomas Heine, Berthold Kersting
A macrocyclic ligand (H2 L) containing two o,o'-bis(iminomethyl)phenol and two calix[4]arene head units has been synthesized and its coordination chemistry towards divalent Ni and Zn investigated. The new macrocycle forms complexes of composition [ML] (M=Zn, M=Ni) and [ZnL(py)2 ], which were characterized by elemental analysis; IR, UV/Vis, and NMR spectroscopy; electrospray ionization mass spectrometry (ESI-MS); and X-ray crystallography (for [ZnL(py)2 ] and [NiL]). H2 L allows the sensitive optical detection of Zn(2+) among a series of biologically relevant metal ions by a dual fluorescence enhancement/quenching effect in solution...
February 13, 2017: Chemistry: a European Journal
Hang Yuan, Jie Liu, Yuexiang Lu, Zhe Wang, Guoyu Wei, Tianhao Wu, Gang Ye, Jing Chen, Sichun Zhang, Xinrong Zhang
Plasmon-enhanced fluorescence (PEF) generally requires the samples settled on a metal substrate and the effective enhancement distance is less than 100 nm, which limit its application in intracellular sensing. Herein, we report a nano endoscopy with PEF effect for sensing analytes inside the extremely small volume samples. The nano endoscopy was fabricated by assembling single nanoporous gold nanowire (PGNW) on the tip of a tungsten needle. It was accurately manipulated to insert into a micro droplet, and an effective sensing was realized at micrometre scale with submicrometer resolution...
January 17, 2017: Analytical Chemistry
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