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Metal enhanced fluorescence

Tanveer A Khan, Monika Sheoran, Venkata Nikhil Raj M, Surbhi Jain, Diksha Gupta, Sunil G Naik
Reported herein the synthesis, characterization and biologically important zinc ion binding propensity of a weakly fluorescent chemosensor, 4-methyl-2,6-bis((E)-(2-(4-phenylthiazol-2-yl)hydrazono)methyl)phenol (1). (1)H NMR spectroscopic titration experiment reveals the binding knack of 1 to the essential Zn(2+). The photo-physical studies of 1 exhibit an enhancement in the fluorescence by several folds upon binding with the zinc ions attributed to PET-off process, with a binding constant value of 5.22×10(3)M(-1)...
August 9, 2017: Spectrochimica Acta. Part A, Molecular and Biomolecular Spectroscopy
Dipti Singharoy, Sourav Chowdhury, Soumya Sundar Mati, Swadesh Ghosh, Krishnananda Chattopadhyay, Subhash Chandra Bhattacharya
The sole existence of t-bone shape napthalimide derivative [2-(2-aminoethyl)-1H-benzo[de]isoquinoline-1,3(2H)-dione] (NAP) which in turn gives rise to a PET mechanism, has been established using a combination of experimental and theoretical studies. In parallel an in vitro-in cell PET mechanism has also been shown. To understand the photo physics of NAP, solvent studies have been carried out in different solvents. In addition, theoretical calculations have been resorted to explain the spectroscopic properties through optimized structures...
August 17, 2017: Chemistry: a European Journal
Novina Malviya, Mriganka Das, Poulami Mandal, Suman Mukhopadhyay
A carboxamide based molecule has shown unique gelation property in an aqueous mixture of DMF or DMSO. The gel itself has shown aggregation-induced fluorescence enhanced emission (AIEE), which can be utilized effectively in sensing ferrous and ferric ions as both of them switch off the fluorescence completely. An investigation by IR spectroscopy reveals an enhanced π interaction of nitrile group with the iron center and this could be the possible reason behind the complete quenching of AIEE. This molecule was further investigated for the formation of metallogels for a wide array of cations, which in turn can act in tandem to behave as a dynamic array to detect several anions by either switching off or switching on the emission property of the metallogels...
August 15, 2017: Soft Matter
Claudia Wilke, Astrid Barkleit, Thorsten Stumpf, Atsushi Ikeda-Ohno
In case radioactive materials are released into the environment, their incorporation into our digestive system would be a significant concern. Trivalent f-elements, i.e., trivalent actinides and lanthanides, could potentially represent a serious health risk due to their chemo- and radiotoxicity, nevertheless the biochemical behavior of these elements are mostly unknown even to date. This study, therefore, focuses on the chemical speciation of trivalent f-elements in the human gastrointestinal tract. To simulate the digestive system artificial digestive juices (saliva, gastric juice, pancreatic juice and bile fluid) were prepared...
August 4, 2017: Journal of Inorganic Biochemistry
Adam Roberge, Jennifer L Stein, Yi Shen, Brandi M Cossairt, Andrew B Greytak
Recently the addition of M2+ Lewis acids (M = Cd, Zn) to InP quantum dots has been shown to enhance the photoluminescence quantum yield (PL QY). Here we investigate the stability of this Lewis acid layer to post synthetic processing such as purification and ligand exchange. We utilize gel permeation chromatography to purify the quantum dot samples as well as to aid in the ligand exchange reactions. The Lewis acid-capped particles are stable to purification and maintain the enhanced luminescent properties. We demonstrate successful ligand exchange on the quantum dots by switching the native carboxylate ligands to phosphonate ligands...
August 11, 2017: Journal of Physical Chemistry Letters
Pritam Torawane, Karunesh Keshav, Mukesh K Kumawat, Rohit Srivastava, Thangaraj Anand, Suban Sahoo, Amulrao Borse, Anil Kuwar
A new terephthaldehyde-based chemosensor 1 bearing an aminophenol recognition unit has been synthesized and applied to the fluorescent sensing of metal ions. Molecular system 1 acts as a highly selective and sensitive fluorescence turn-on sensor for Cu(2+). The sensing mechanism has been explored. It is proposed that Cu(2+) binds with the imine and hydroxyl moiety of 1 in 1 : 2 binding stoichiometry, thereby enhancing the fluorescence at 386 nm. The detection limit and association constant (Ka) of 1 with Cu(2+) were found to be 0...
August 11, 2017: Photochemical & Photobiological Sciences
Saleh Shahabivand, Azar Parvaneh, Ali Asghar Aliloo
Cadmium (Cd) pollution in the soil threatens the quality of environmental health, and deleteriously affects physiological activities of crops. Symbiosis of endophytic fungi with various plants is a promising manner to improving numerous plant characteristics and remediating heavy metal-polluted soils. In this pot experiment, the influence of root endophyte fungus Piriformospora indica on growth, physiological parameters and organs Cd accumulation in sunflower cv. Zaria plants under the toxic levels of Cd (0, 40, 80 and 120mg/kg soil) were studied...
August 4, 2017: Ecotoxicology and Environmental Safety
Bo Qi, Xiangyang Guo, Yunyi Gao, Dong Li, Jiancheng Luo, Hui Li, Seyed Ali Eghtesadi, Cheng He, Chunying Duan, Tianbo Liu
The predesigned metal organic macrocycle Zn3QDB3(NO3)4 (Zn-QDB) was observed to self-assemble into a hollow, spherical, single-layered "blackberry"-type structure. The self-assembly behaviors of the Zn-QDB are significantly influenced by additional small ions. Specifically, the cations exhibit strong co-ion effects on the interaction between cationic macrocycles which are different from the previously reported co-ion effects of simple anions on anionic polyoxometalates. This unusual phenomenon is due to the unique cation-π interaction between small cations and electron-rich cavity of Zn-QDB, as confirmed by UV-vis, (1)H-NMR and fluorescence spectra...
August 4, 2017: Journal of the American Chemical Society
Zhenzhen Shang, Mingchao Yang, Luogen Deng
Energy transfer is known to have a significant influence on random lasers. However, the study about the effect of energy transfer between metallic salt and dye molecules on random lasers is still lacking at present. Here, we investigate random lasing actions in Pyrromethene-597 (PM597), PM597-doped MnCl₂ (manganese (II) chloride), PM597-doped polymer-dispersed liquid crystal (PDLC) and PM597-doped PDLC with MnCl₂ capillary systems. We find that random lasing of the systems with MnCl₂ exhibits lower threshold, higher intensity, sharper peak and variable resonance wavelength in comparison with the systems without MnCl₂...
August 24, 2016: Materials
Qiong Zhang, Xiaohe Tian, Hongping Zhou, Jieying Wu, Yupeng Tian
The application of two-photon absorption (2PA) materials is a classical research field and has recently attracted increasing interest. It has generated a demand for new dyes with high 2PA cross-sections. In this short review, we briefly cover the structure-2PA property relationships of organic fluorophores, organic-inorganic nanohybrids and metal complexes explored by our group. (1) The two-photon absorption cross-section (δ) of organic fluorophores increases with the extent of charge transfer, which is important to optimize the core, donor-acceptor pair, and conjugation-bridge to obtain a large δ value...
February 23, 2017: Materials
Steffen Kist, Venumadhav Korampally
We report on a non-destructive method for evaluating fluorescence emission from fluorophores placed upon engineered photonic structures. Our method utilizes re-usable, fluorescent thin film coated polydimethylsiloxane (PDMS) stamps. We harness the inherent characteristics of PDMS slabs; their ability to form conformal contact through van der Waals interactions in bringing the coated fluorescent layer on PDMS into close proximity of the photonic structure of interest. Fluorescence measurements are performed using the PDMS slab while in conformal contact with the test structure, allowing one to re-use these stamps for reliable evaluation over multiple samples...
August 3, 2017: Analyst
Somsubhra Maity, Wei-Chen Wu, Joseph B Tracy, Laura I Clarke, Jason R Bochinski
Anisotropically-shaped metal nanoparticles act as nanoscale heaters via excitation of a localized surface plasmon resonance, utilizing a photothermal effect which converts the optical energy into local heat. Steady-state temperatures within a polymer matrix embedded with gold nanorods undergoing photothermal heating using continuous-wave excitation are measured in the immediate spatial vicinity of the nanoparticle (referred to as the local temperature) from observing the rate of physical rotation of the asymmetric nanoparticles within the locally created polymer melt...
August 3, 2017: Nanoscale
Natarajan Vijay, Gopal Balamurugan, Parthiban Venkatesan, Shu Pao Wu, Sivan Velmathi
A triple action chemosensor (R1) bearing a rhodamine and thiophene moiety was synthesized by a simple condensation reaction. The sensing behaviour and selectivity of the synthesized chemosensor toward metal ions were studied by UV-Vis and fluorescence spectroscopy. The chemosensor recognized Cu(2+) and Cr(3+) ions with significant changes in UV-Vis absorbance and fluorescence intensity. The results showed that Cr(3+) induced greater fluorescence enhancement whereas Cu(2+) ions bound strongly with the receptor by showing a strong absorption band at 554 nm but with weak fluorescence...
August 2, 2017: Photochemical & Photobiological Sciences
Sihai Hu, Yaoguo Wu, Na Yi, Shuai Zhang, Yuanjing Zhang, Xu Xin
Dissolved organic matter (DOM), as the most active organic carbon in the soil, has a coherent affinity with heavy metals from inherent and exogenous sources. Although the important roles of DOM in the adsorption of heavy metals in soil have previously been demonstrated, the heterogeneity and variability of the chemical constitution of DOM impede the investigation of its effects on heavy metal adsorption onto soil under natural conditions. Fresh DOM (FDOM) and degraded DOM (DDOM) from sugarcane rind were prepared, and their chemical properties were measured by Fourier-transform infrared spectrometry (FTIR), excitation-emission matrix (EEM) fluorescence spectroscopes, nuclear magnetic resonance (NMR), and molecular weight distribution (MWD)...
August 1, 2017: Environmental Science and Pollution Research International
Jayasmita Jana, Teresa Aditya, Mainak Ganguly, Shyamal Kumar Mehetor, Tarasankar Pal
Metal enhanced fluorescence of carbon dots has been reported in aqueous solution. Moderately fluorescing carbon dots (λex=360nm and λem=440nm) of 6-8nm diameters (CDA) have been synthesized from freshly prepared aqueous ascorbic acid solution under modified hydrothermal treatment. The CDA fluorescence is quenched at the close proximity with gold nanoparticles (AuNPs). Here, a substrate specific near-field electric field distribution is pronounced. Anticipating distance dependent fluorescence enhancement phenomenon, long-chain aliphatic thiol capped AuNPs are introduced to improve fluorescence of moderately fluorescing CDAs...
July 24, 2017: Spectrochimica Acta. Part A, Molecular and Biomolecular Spectroscopy
Adam B Taylor, Peter Zijlstra
Single-molecule detection has long relied on fluorescent labeling with high quantum-yield fluorophores. Plasmon-enhanced detection circumvents the need for labeling by allowing direct optical detection of weakly emitting and completely nonfluorescent species. This review focuses on recent advances in single molecule detection using plasmonic metal nanostructures as a sensing platform, particularly using a single particle-single molecule approach. In the past decade two mechanisms for plasmon-enhanced single-molecule detection have been demonstrated: (1) by plasmonically enhancing the emission of weakly fluorescent biomolecules, or (2) by monitoring shifts of the plasmon resonance induced by single-molecule interactions...
August 8, 2017: ACS Sensors
Feng Shan, Xiao-Yang Zhang, Xing-Chang Fu, Li-Jiang Zhang, Dan Su, Shan-Jiang Wang, Jing-Yuan Wu, Tong Zhang
One of the main challenges for highly sensitive surface-enhanced Raman scattering (SERS) detection is the noise interference of fluorescence signals arising from the analyte molecules. Here we used three types of gold nanostars (GNSs) SERS probes treated by different surface modification methods to reveal the simultaneously existed Raman scattering enhancement and inhibiting fluorescence behaviors during the SERS detection process. As the distance between the metal nanostructures and the analyte molecules can be well controlled by these three surface modification methods, we demonstrated that the fluorescence signals can be either quenched or enhanced during the detection...
July 28, 2017: Scientific Reports
Zdeněk Farka, Tomáš Juřík, David Kovář, Libuše Trnková, Petr Skládal
We review the progress achieved during the recent five years in immunochemical biosensors (immunosensors) combined with nanoparticles for enhanced sensitivity. The initial part introduces antibodies as classic recognition elements. The optical sensing part describes fluorescent, luminescent, and surface plasmon resonance systems. Amperometry, voltammetry, and impedance spectroscopy represent electrochemical transducer methods; electrochemiluminescence with photoelectric conversion constitutes a widely utilized combined method...
August 9, 2017: Chemical Reviews
Shuwei Zhang, Tzu-Ho Chen, Hsien-Ming Lee, Jianheng Bi, Avik Ghosh, Mingxi Fang, Zichen Qian, Fei Xie, Jon Ainsley, Christo Christov, Fen-Tair Luo, Feng Zhao, Haiying Liu
Two water-soluble near-infrared luminescent probes, which possess both conventional intense Stokes fluorescence and unique single-photon frequency upconversion luminescence (FUCL), were developed for sensitive and selective detection of pH changes in live cells. The water solubility and biocompatibility of these probes were achieved by introducing mannose residues through 2,2'-(ethylenedioxy)diethylamine tethered spacers to a near-infrared conventional fluorescence (CF) and FUCL organic fluorophore. At a pH higher than 7...
July 28, 2017: ACS Sensors
Mindan Lu, Ning Kang, Chuan Chen, Liuqing Yang, Yang Li, Minghui Hong, Xiangang Luo, Lei Ren, Xiumin Wang
Near infrared (NIR) triggered cyanine dyes have attracted considerable attentions in multi-modal tumor theranostics. However, near infrared (NIR) cyanine dyes used in tumor treatment often suffer from low fluorescence intensity and weak singlet oxygen generation efficiency, resulting in inadequate diagnostic and therapy efficacies for tumors. It is still a great challenge to improve both the photodynamic therapy (PDT) and fluorescent imaging (FLI) efficacy of cyanine dyes in tumor applications. Herein, a novel multifunctional nanoagent of AuNRs@SiO2-IR795 was developed to realize the integrated photothermal/photodynamic therapy (PTT/PDT) and FLI at a very low dosage of IR795 (0...
July 25, 2017: Nanotechnology
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