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Metal enhanced fluorescence

Ren-Wu Huang, Yong-Sheng Wei, Xi-Yan Dong, Xiao-Hui Wu, Chen-Xia Du, Shuang-Quan Zang, Thomas C W Mak
Silver(i) chalcogenide/chalcogenolate clusters are promising photofunctional materials for sensing, optoelectronics and solar energy harvesting applications. However, their instability and poor room-temperature luminescent quantum yields have hampered more extensive study. Here, we graft such clusters to adaptable bridging ligands, enabling their interconnection and the formation of rigid metal-organic frameworks. By controlling the spatial separation and orientation of the clusters, they then exhibit enhanced stability (over one year) and quantum yield (12...
July 2017: Nature Chemistry
Jian-Feng Li, Chao-Yu Li, Ricardo F Aroca
Fluorescence spectroscopy with strong emitters is a remarkable tool with ultra-high sensitivity for detection and imaging down to the single-molecule level. Plasmon-enhanced fluorescence (PEF) not only offers enhanced emissions and decreased lifetimes, but also allows an expansion of the field of fluorescence by incorporating weak quantum emitters, avoiding photobleaching and providing the opportunity of imaging with resolutions significantly better than the diffraction limit. It also opens the window to a new class of photostable probes by combining metal nanostructures and quantum emitters...
June 22, 2017: Chemical Society Reviews
Xiao Lian, Tifang Miao, Xiaoyu Xu, Chi Zhang, Bing Yan
The harm of plastic pollutants for human and environment is being paid more and more attention. Polystyrene (PS) and styrene are toxic compounds used in large quantities in the production of fiberglass reinforced polyesters. In this work, a simple method was designed for independent detecting polystyrene and styrene biomarker (phenylglyoxylic acid, PGA) in serum and urine. We prepared Eu3+ functionalized Sc-based metal-organic frameworks as turn-on fluorescent switch for PGA. The distinct enhanced luminescence is observed from the Eu@MOFs with addition of PGA...
June 10, 2017: Biosensors & Bioelectronics
A C Gonçalves, J Luis Capelo, C Lodeiro, A A Dos Santos
A new selenium containing coumarin (compound 7) was designed and synthesized from the amide linkage between coumarin-519 (6) and 2-(butylselanyl)ethanamine (5). The molecular structure of 7 was accurately characterized, and its photophysical properties in acetonitrile, ethanol and chloroform solutions were studied by absorption, stationary and time-resolved fluorescence spectroscopies. Changes in the solvent polarity affected the Stokes shift, quantum yields and lifetime of the excited states. The spectroscopic behavior of compound 7 was evaluated in the presence of different monovalent, divalent and trivalent metallic cations (Na(+), K(+), Ca(2+), Co(2+), Ni(2+), Cu(2+), Zn(2+), Cd(2+), Pb(2+), Hg(2+), Hg(+), Ag(+), Al(3+), Fe(3+), Ga(3+) and Cr(3+)) in acetonitrile solution...
June 12, 2017: Photochemical & Photobiological Sciences
Jing Li, Shuhua Han
A novel chemosensor TrisRh based on tris(2-aminoethyl)amine and rhodamine 6G is designed and synthesized as a fluorescence turn-on probe for Co(2+) ions that is paramagnetic with a property of quenching fluorescence. Rhodamine spirolactam forms are nonfluorescent, whereas, ring-opening of corresponding spirocyclic induced by Co(2+) results in strong fluorescence emission. Upon the addition of Co(2+) ions, TrisRh can display significant enhancements in absorbance and fluorescence intensity as well as evident colorific transformation, which can be perceived by the naked eye...
June 7, 2017: Luminescence: the Journal of Biological and Chemical Luminescence
Keyur D Bhatt, Hemangini D Shah, Manthan Panchal
A new fluorescence receptor calix[4]pyrrole-N-(quinoline-8-yl) acetamide (CAMQ) containing a pyrrolic ring connected via the meso-position was synthesized, purified and characterized by elemental analysis, NMR and mass spectroscopy. This compound was examined for its fluorescence properties towards different metal ions e.g. Ag(I), Hg(II), Co(II), Ca(II), Ni(II), Zn(II), Cr(II), Ba(II), Fe(II), Cu(II), Pb(II)and Mg(II) ions by spectrophotometry and spectrofluorometry. It was concluded that the compound (CAMQ) possessed significantly enhanced selectivity for Pb(II) and Cu(II) ions in dimethyl sulfoxide (DMSO) even at very low concentrations (1 μM)...
June 7, 2017: Luminescence: the Journal of Biological and Chemical Luminescence
Najim Akhtar, Sanjay Kisan Metkar, Agnishwar Girigoswami, Koyeli Girigoswami
Zinc oxide (ZnO) is a semiconductor metal oxide nanoparticle with inherent optical properties. Among the different zinc oxide nanostructures, nanoflowers have greater surface area. Utilizing this property a reagentless biosensor has been developed for the detection of beta amyloids, a hallmark of neurodegenerative diseases like Alzheimer's disease, Creutzfeldt-Jakob Syndrome, insulin dependent type II diabetes etc. The poor fluorescence quantum yield and photobleaching effect of Thioflavin T (ThT) upon binding to the model insulin amyloid beta sheets in solution can be overcome by the present engineered biosensor where ThT acts as a target as well as a reporter to detect amyloids adsorbed on a solid template based on ZnO nanoflower...
September 1, 2017: Materials Science & Engineering. C, Materials for Biological Applications
Keying Cai, Mulan Zeng, Fenfen Liu, Nan Liu, Zhenzhong Huang, Yonghai Song, Li Wang
An easy and effective strategy for synthesizing a ratiometric fluorescent nanosensor has been demonstrated in this work. Novel fluorescent BSA-AuNPs@Tb-AMP (BSA, bovine serum albumin; AMP, adenosine 5'-monophosphate; AuNPs, Au nanoparticles) metal-organic framework (MOF) nanostructures were synthesized by encapsulating BSA-AuNPs into Tb-AMP MOFs for the detection of 2,6-pyridinedicarboxylic acid (DPA) and Hg(2+) . DPA could strongly co-ordinate with Tb(3+) to replace water molecules from the Tb(3+) center and accordingly enhanced the fluorescence of Tb-AMP MOFs...
June 1, 2017: Luminescence: the Journal of Biological and Chemical Luminescence
Jing-Xing Wu, Bing Yan
A highly fluorescent metal-organic framework (In-MOF, In(OH)bpydc (bpydc=biphenyl-5,5'-dicarboxylate)) imparting additional luminescent Eu(3+) ions has been synthesized for sensing organic molecules and anions, especially chloroform and MnO4(-), both of them have a significant spectral response. This Eu(3+)-incorporated hybrid (In-MOF-Eu) has been fully characterized, which reveals large surface area, great pore size, favorable thermal stability, excellent luminescence as well as good fluorescence stability...
May 19, 2017: Journal of Colloid and Interface Science
Tânia Ribeiro, Carlos Baleizão, José Paulo S Farinha
Metal nanoparticles can either quench or enhance the emission of dyes in their vicinity, but the precise measurement and understanding of this effect is still hindered by experimental artifacts, especially for particles in colloidal dispersion. Here, we introduce a new methodology to correct the inner filter effect of the metal on the dye emission. To test the method, we developed new hybrid nanoparticles with a gold core and a silica shell of precise thickness (tuned from 7 to 13 nm), with a high quantum yield perylenediimide dye on the surface...
May 26, 2017: Scientific Reports
Trisha Das, Ankita Roy, Hiroshi Uyama, Partha Roy, Mahasweta Nandi
Mesoporous silica functionalized with a 2-hydroxy-naphthyl moiety has been synthesized and characterized by standard techniques like powder X-ray diffraction, N2 adsorption/desorption studies, transmission electron microscopy and spectral studies like FT-IR, UV-visible, fluorescence and (13)C and (29)Si solid state NMR. The functionalized silica material showed significant enhancement in its emission intensity in the presence of Al(3+) ions whereas other metal ions could not bring about any increase in its emission intensity...
June 6, 2017: Dalton Transactions: An International Journal of Inorganic Chemistry
Chen Wang, Li Tian, Wei Zhu, Shiqiang Wang, Peng Wang, Yun Liang, Wanlin Zhang, Hongwei Zhao, Guangtao Li
By incorporating a cationic dye within a metal-organic framework (MOF) through an ion-exchange process, a responsive dye@bio-MOF-1 composite has been synthesized, serving as a dual-emitting platform for enhanced detection of different kinds of nitro-explosives, especially nitroalkanes, nitramines, and nitrate esters. The dye@bio-MOF-1 composite was constructed with free amines on their well-defined cavities, which is essential for the capture of explosives into their confined nanospace. It was observed that the encapsulation of explosives into the constructed dye@bio-MOF-1 composite could dramatically alter the luminescent properties of the dyes as well as the MOF skeletons owing to the size exclusivity and confinement-induced effect...
June 5, 2017: ACS Applied Materials & Interfaces
Boran Wu, Xiaohu Dai, Xiaoli Chai
The production of sewage sludge with the presence of various contaminants has been a serious issue for the operation of wastewater treatment plants on both the economical and environmental sides. To minimize the sludge volume to be handled and limit the potential environmental risk, this study developed a novel oxidative leaching process for enhanced sewage sludge dewatering and simultaneous removal of heavy metals based on nano-CaO2. Response surface methodology determined the following optimal conditioning parameters in terms of capillary suction time reduction: 0...
May 24, 2017: Environmental Science and Pollution Research International
Chonticha Sahub, Gamolwan Tumcharern, Prae Chirawatkul, Vithaya Ruangpornvisuti, Sanong Ekgasit, Supasorn Wanichweacharungruang, Thawatchai Tuntulani, Tanapat Palaga, Boosayarat Tomapatanaget
At present, strategies to disperse hydrophobic molecules in water without altering their chemical structures include conventional surfactant-based micellar and vesicular systems, encapsulation into water dispersible polymeric nanoparticles, and loading onto the surface of various metal nanoparticles. Here, we report a simple and low cost platform to incorporate hydrophobic molecules into a stable water dispersible nanostructure that can significantly increase the stability of the encapsulated materials. The platform is based on the incorporation of hydrophobic molecules into the self-assembled complex of gadolinium ion (Gd(3+)), sodium dodecyl sulfate (SDS), and 4-(2-hydroxyethyl)-1-piperazineethanesulfonic acid (HEPES) called GdSH...
May 13, 2017: Colloids and Surfaces. B, Biointerfaces
Ming Xu, Shuai Yuan, Xin-Yu Chen, Yu-Jie Chang, Gregory Day, Zhi-Yuan Gu, Hong-Cai Zhou
Two-dimensional metal-organic framework (MOF) nanosheets are utilized as effective enzyme inhibitors, providing an inspiring means to enhance the control of cellular processes as well as improve our understanding of the surface chemistry between MOFs and enzymes. In this paper, we demonstrated that the activity of α-chymotrypsin (ChT) can be effectively inhibited with 96.9% inhibition by 2-D Cu(bpy)2(OTf)2 nanosheets, while Zn2(bim)4 nanosheets show no significant inhibition effect toward ChT. Kinetic studies revealed that the material acts as a competitive inhibitor toward ChT...
June 21, 2017: Journal of the American Chemical Society
Huiyuan Zhang, Wei Jiang, Ruiling Liu, Jing Zhang, Di Zhang, Zhonghao Li, Yuxia Luan
Conventional organic and inorganic drug nanocarriers suffer from serious drawbacks such as low drug-storage capacity and uncontrolled release. Moreover, multidrug resistance (MDR) has been one of the primary causes leading to chemotherapy failure for cancers. The main reason for MDR is the overexpressed active efflux transporters such as P-glycoprotein. Here, zeolitic imidazolate framework ZIF-8, as one of the biocompatible metal organic frameworks (MOFs), is reported for the first time as the multidrug carrier to realizing the efficient codelivery of verapamil hydrochloride (VER) as the P-glycoprotein inhibitor as well as doxorubicin hydrochloride (DOX) as an anticancer drug to overcome the MDR in addition to realize the active targeted ability for an efficient anticancer effect...
May 31, 2017: ACS Applied Materials & Interfaces
Qingshan Wei, Guillermo Acuna, Seungkyeum Kim, Carolin Vietz, Derek Tseng, Jongjae Chae, Daniel Shir, Wei Luo, Philip Tinnefeld, Aydogan Ozcan
Smartphone fluorescence microscopy has various applications in point-of-care (POC) testing and diagnostics, ranging from e.g., quantification of immunoassays, detection of microorganisms, to sensing of viruses. An important need in smartphone-based microscopy and sensing techniques is to improve the detection sensitivity to enable quantification of extremely low concentrations of target molecules. Here, we demonstrate a general strategy to enhance the detection sensitivity of a smartphone-based fluorescence microscope by using surface-enhanced fluorescence (SEF) created by a thin metal-film...
May 18, 2017: Scientific Reports
Zhen Lei, Hua Zhang, Yaoqi Wang, Xianying Meng, Zhenxin Wang
Matrix metalloproteinases (MMPs) are closely associated with cancer cell invasion and metastasis. Herein, a fluorescence resonance energy transfer (FRET)-peptide microarray-based metal enhanced fluorescence (MEF) assay is proposed for multiple and sensitive profiling of MMPs activities on a novel Au/Ag@SiO2 substrate. The Au/Ag@SiO2 substrate is prepared by electroless deposition of silver on gold nanoparticle (GNP) seeds, followed by SiO2 shell coating and surface functionalization. The specific FRET peptides are spotted on the Au/Ag@SiO2 substrate to sensitively detect MMPs (MMP-2, -3, -7, -9, -14) via fluorescence recovery by the MMP cleavage of quenched peptide motifs and further enhanced by MEF...
May 26, 2017: Analytical Chemistry
Jing Zhang, Qing Tang, Zhongzheng Gao, Sheng Chao Qiu, Ying Huang, Zhu Tao
A water-soluble fluorescent sensor based on the interaction of the twisted cucurbit[14]uril (tQ[14]) and thiazole orange (TO) in aqueous solution has been developed. Formation of the tQ[14]/TO complex gives rise to strong fluorescence in both of neutral and acidic aqueous solutions compared with that of free TO. Further experiments on the interaction of the tQ[14]/TO complex with metal ions revealed that from a series of nineteen selected common metal ions, 1) only Hg2+ ion can lead to the fluorescence enhancement and then quenching of the tQ[14]/TO complex (2:1) in neutral aqueous solution; 2) only Ba2+ can induce fluorescence quenching of the tQ[14]/TO (2:1) complex in aqueous HCl solution (pH 2)...
May 16, 2017: Chemistry: a European Journal
Nathaniel P Endicott, Eries Lee, Timothy A Wencewicz
Staphylococcus aureus produces a cocktail of metallophores (staphylopine, staphyloferrin A, and staphyloferrin B) to scavenge transition metals during infection of a host. In addition, S. aureus displays the extracellular surface lipoproteins FhuD1 and FhuD2 along with the ABC transporter complex FhuCBG to facilitate the use of hydroxamate xenosiderophores such as desferrioxamine B (DFOB) for iron acquisition. DFOB is used as a chelation therapy to treat human iron overload diseases and has been linked to an increased risk of S...
May 30, 2017: ACS Infectious Diseases
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