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Metal enhanced fluorescence

Kaichen Dong, Yang Deng, Xi Wang, Kyle B Tom, Zheng You, Jie Yao
Dissipative loss in optical materials is considered one of the major challenges in nano-optics. Here we show that, counter-intuitively, a large imaginary part of material permittivity contributes positively to subwavelength light enhancement and confinement. The Purcell factor and the fluorescence enhancement of dissipative dielectric bowtie nanoantennas, such as Si in ultraviolet (UV), are demonstrated to be orders of magnitude higher than their lossless dielectric counterparts, which is particularly favorable in deep UV applications where metals are plasmonically inactive...
April 15, 2018: Optics Letters
Ya-Ping Huang, Sheng-Chao Huang, Xiang-Jie Wang, Nataraju Bodappa, Hao Yin, Chao-Yu Li, Hai-Sheng Su, Meng Meng, Hua Zhang, Bin Ren, Zhi-Ling Yang, Renato Zenobi, Zhong-Qun Tian, Jian-Feng Li
Tip-enhanced Raman spectroscopy can provide molecular fingerprint information with ultrahigh spatial resolution, but the tip will be easily contaminated, thus leading to artifacts. It also remains a great challenge to establish tip-enhanced fluorescence due to quenching resulting from the proximity of the metal tip. Herein, we report shell-isolated tip enhanced Raman and fluorescence spectroscopies by employing ultrathin shell-isolated tips fabricated by atomic layer deposition. Such shell-isolated tips not only show outstanding electromagnetic field enhancement in TERS, but also exclude interference by contaminants, thus greatly promoting applications in solution...
April 12, 2018: Angewandte Chemie
Da Zhang, Ming Wu, Zhixiong Cai, Naishun Liao, Kun Ke, Hongzhi Liu, Ming Li, Gang Liu, Huanghao Yang, Xiaolong Liu, Jingfeng Liu
A novel metal-organic particle (MOP) based nanodrug formed by mild self-assembly of chemotherapeutic drugs, including banoxantrone and doxorubicin, through Cu(II)-mediated coordination effects, is reported. In this nanodrug, Cu(II) acts as a bridge to join AQ4N and DOX, and then, self-assembly of [-AQ4N-Cu(II)-(DOX)2 -Cu(II)-] n complexes forms nanosized MOPs (referred to as ADMOPs) through multiple interactions including host-metal-guest coordination, hydrophobic interactions, π-stacking, and van der Waals force...
February 2018: Advanced Science (Weinheim, Baden-Wurttemberg, Germany)
Jung Woo Leem, Seong-Ryul Kim, Kwang-Ho Choi, Young L Kim
The recent advances in photocatalysis have opened a variety of new possibilities for energy and biomedical applications. In particular, plasmonic photocatalysis using hybridization of semiconductor materials and metal nanoparticles has recently facilitated the rapid progress in enhancing photocatalytic efficiency under visible or solar light. One critical underlying aspect of photocatalysis is that it generates and releases reactive oxygen species (ROS) as intermediate or final products upon light excitation or activation...
2018: Nano Convergence
Huanhuan Li, Quansheng Chen, Md Mehedi Hassan, Qin Ouyang, Tianhui Jiao, Yi Xu, Min Chen
Mercury ion (Hg2+ ) is a highly hazardous and widespread pollutant with bio-accumulative properties. Although the existing Hg2+ detection methods have high sensitivity and reliability, whereas there have few reports concerning bimodal detection for Hg2+ with one sensor. Toward this goal, a novel sensor based on rhodamine derivatives (RhD) grafted AuNS@Ag core-shell nanocubes (CSN) has been synthesized and shown the bimodal detection capabilities with metal enhanced fluorescence (MEF) and surface enhanced Raman scattering (SERS) for Hg2+ ...
August 14, 2018: Analytica Chimica Acta
Jike Lu, Pei Wang, Zhaodi Ke, Xin Liu, Qiaozhen Kang, Limin Hao
In order to study the effect of metal ions on the enzymatic hydrolysis of hemp seed oil by Candida sp. 99-125, the spectroscopy, stability and hydrolytic activity of the biocatalyst were investigated in presence of Ca2+ , Mg2+ , Fe2+ , Fe3+ , Cu2+ , Sn2+ , Pb2+ , Zn2+ and Ba2+ metal ions, respectively. The UV spectroscopy showed that all the metal ions enhanced the absorbance but the decrease of fluorescence intensity was observed. All the metal ions could improve the lipase thermal stability except Cu2+ and Ba2+ ...
March 28, 2018: International Journal of Biological Macromolecules
Xi Li, Zheng Li, Ying-Wei Yang
A luminescent conjugated macrocycle polymer (CMP) with strong two-photon fluorescence property, namely, P[5]-TPE-CMP, is constructed from ditriflate-functionalized pillar[5]arene and a 1,1,2,2-tetrakis(4-ethynylphenyl)ethylene (TPE) linker through a Sonogashira-Hagihara cross-coupling reaction. Significantly, in sharp contrast with the corresponding conjugated microporous polymer without synthetic macrocycles, P[5]-TPE-CMP shows an outstanding stability against photobleaching and exhibits highly selective cation sensing capability toward Fe3+ at different excitation wavelengths (both UV and red-near-infrared regions)...
March 30, 2018: Advanced Materials
Naimeh Hashemi, Zahra Vaezi, Mosslim Sedghi, Hossein Naderi-Manesh
The authors describe a novel water-soluble, stable, biocompatible, and highly fluorescent probe consisting of iron quantum clusters incorporated into human adult hemoglobin (Hb-FeQCs). The Hb-FeQCs were characterized by various spectroscopic techniques. The probe displays strong absorption and yellow fluorescence with a peak centered at 567 nm (photo-excited at 460 nm). The Hb-FeQCs show excellent photostability over a wide range of pH values (5-12), even in the presence of high electrolyte concentrations...
December 18, 2017: Mikrochimica Acta
Laxman S Walekar, Peidong Hu, Feng Liao, Xiaoyan Guo, Mingce Long
The authors describe a fluorometric and colorimetric nanoprobe for H2 O2 . The detection scheme is based on the in-situ formation of silver(I) ions from a composite consisting of nitrogen-doped carbon quantum dots (N-CQDs) and silver nanoparticles (AgNPs). A drastic change occurs both in fluorescence and color of the solution of the N-CQD/AgNPs composite. The fluorescence of composite (with excitation/emission peaking at 320/384 nm) is enhanced on increasing the concentration of H2 O2 due to the oxidation of silver metal in the N-CQD/AgNPs to form Ag(I) ions...
December 6, 2017: Mikrochimica Acta
Xue Zhang, Hengxiang Li, Qing Cao, Li'e Jin, Fumeng Wang
The managing and recycling of waste tires has become a worldwide environmental challenge. Among the different disposal methods for waste tires, pyrolysis is regarded as a promising route. How to effectively enhance the added value of pyrolytic residue (PR) from waste tires is a matter of great concern. In this study, the PRs were treated with hydrochloric and hydrofluoric acids in turn under ultrasonic waves. The removal efficiency for the ash and sulfur was investigated. The pyrolytic carbon black (PCB) obtained after treating PR with acids was analyzed by X-ray fluorescence spectrophotometry, Fourier transform infrared spectrometry, X-ray diffractometry, laser Raman spectrometry, scanning electron microscopy, thermogravimetric (TG) analysis, and physisorption apparatus...
March 1, 2018: Waste Management & Research
Xiao-Song Wang, Dapeng Liu
Hydrophobic Hydration (HH) is crucial in protein chemistry. Its role in the organization of molecules in water, however, remains elusive and difficult to investigate without appropriate model systems. Metal Carbonyl vesicles (MCsomes), assembled from hydrophobic Fp(CH2)6Azobenzenetrans (Fp head = (PPh3)(Cp)Fe(CO)(CO-); hydrocarbon tail = (CH2)6Azobenzenetrans; trans: trans configuration) is dispersible in water via HH of the Fp heads. We examined the dependence of this HH on solution conditions by taking advantage of redox activity and fluorescence quenching ability of hydrated Fe elements...
March 25, 2018: Chemistry: a European Journal
Xiaolin Huang, Jibin Song, Bryant C Yung, Xiaohua Huang, Yonghua Xiong, Xiaoyuan Chen
Exploring and understanding biological and pathological changes are of great significance for early diagnosis and therapy of diseases. Optical sensing and imaging approaches have experienced major progress in this field. Particularly, an emergence of various functional optical nanoprobes has provided enhanced sensitivity, specificity, targeting ability, as well as multiplexing and multimodal capabilities due to improvements in their intrinsic physicochemical and optical properties. However, one of the biggest challenges of conventional optical nanoprobes is their absolute intensity-dependent signal readout, which causes inaccurate sensing and imaging results due to the presence of various analyte-independent factors that can cause fluctuations in their absolute signal intensity...
March 23, 2018: Chemical Society Reviews
Yajuan Li, Jiangbo Guo, Bo Dai, Lijun Geng, Fengjuan Shen, Yajun Zhang, Xudong Yu
Driven by tunable metal-ligand interactions, a polydentate ligand TC containing terpyridine and carboxylic acid units was developed to construct metallo-polymers that showed multiple aggregation modes with controlled macroscopic properties. In the presence of different kind of Zn2+ ions or NaOH, TC could form metallo-polymers via π-π stacking and metal-ligand interaction that further trapped water molecules, resulting in hydrogels and crystals. Moreover, these TC/Zn2+ hydrogels could transform to soluble and fluorescent aggregates in the presence of NaOH due to the formation of binuclear metallo-polymers with enhanced ICT emission...
March 15, 2018: Journal of Colloid and Interface Science
Habib Ali Molla, Rahul Bhowmick, Abu Saleh Musha Islam, Bibhutibhushan Show, Nillohit Mukherjee, Anup Mondal, Mahammad Ali
A novel highly sensitive and selective fluorescent chemosensor L has been synthesized and characterized by various physicochemical techniques. In 3 : 7 water : MeCN (v/v) at pH 7.2 (10 mM HEPES buffer, μ = 0.05 M LiCl), it selectively recognizes Fe3+ through 1 : 1 complexation resulting in a 106-fold fluorescence enhancement and a binding constant of 8.10 × 104 M-1. The otherwise non-fluorescent spirolactam form of the probe results a dual-channel (absorbance and fluorescence) recognition of Fe3+ via CHEF (chelation enhanced fluorescence) through the opening of the spirolactam ring...
March 22, 2018: Photochemical & Photobiological Sciences
Cynthia Al Hageh, Majd Al Assaad, Zeinab El Masri, Nawar Samaan, Mirvat El-Sibai, Christian Khalil, Rony S Khnayzer
Copper is an earth-abundant and a biologically essential metal that offers a promising alternative to noble metals in photochemistry and photobiology. In this work, a series of sterically encumbered Cu(i) bis-phenanthroline complexes were investigated for their use in photochemotherapy (PCT). It was found that Cu(dsbtmp)2+ [dsbtmp = 2,9-disec-butyl-3,4,7,8-tetramethyl-1,10-phenanthroline] (compound 3), which possessed the longest excited state lifetime, exhibited significant in vitro photocytotoxicity on A375 (human malignant melanoma) and A549 (human lung carcinoma) cell lines...
March 20, 2018: Dalton Transactions: An International Journal of Inorganic Chemistry
Jiaohan Guo, Kevin Black, Jiawen Hu, Mahi R Singh
We developed a theory for the fluorescence (FL) for quantum emitter and double metallic nanoshell dimer hybrids using the density matrix method. The dimer is made from two identical double metallic nanoshells, which are made of a dielectric core, a gold metallic shell and a dielectric spacer layer. The quantum emitters are deposited on the surface of the spacer layers of the dimers due to the electrostatic absorptions. We consider that dimer hybrids are surrounded by biological cells. This can be achieved by injecting them in human or animal cells...
March 16, 2018: Journal of Physics. Condensed Matter: An Institute of Physics Journal
Elliot J Taffet, Yoann Olivier, Frankie Lam, David Beljonne, Gregory D Scholes
We report three characteristics of ideal thermally activated delayed fluorescence molecular systems apparent in carbene-metal-amides: (a) an exceptionally small singlet-triplet gap that effectively eliminates the thermal activation barrier to reverse intersystem crossing; (b) significant singlet oscillator strength promoting fluorescence in the region of this small barrier; and (c) enlarged spin-orbit coupling driving reverse intersystem crossing in this region. We carry out highly correlated quantum-chemical calculations to detail the relative energies of and spin-orbit couplings between the singlet and triplet states, finding that they fall closer together in energy and couple more strongly in going from the singlet ground-state to the triplet optimized geometry...
March 15, 2018: Journal of Physical Chemistry Letters
Xiaobin Xu, Shuang Hou, Natcha Wattanatorn, Fang Wang, Qing Yang, Chuanzhen Zhao, Xiao Yu, Hsian-Rong Tseng, Steven J Jonas, Paul S Weiss
An efficient nonviral platform for high-throughput and subcellular precision targeted intracellular delivery of nucleic acids in cell culture based on magnetic nanospears is reported. These magnetic nanospears are made of Au/Ni/Si (∼5 μm in length with tip diameters <50 nm) and fabricated by nanosphere lithography and metal deposition. A magnet is used to direct the mechanical motion of a single nanospear, enabling precise control of position and three-dimensional rotation. These nanospears were further functionalized with enhanced green fluorescent protein (eGFP)-expression plasmids via a layer-by-layer approach before release from the underlying silicon substrate...
March 14, 2018: ACS Nano
Jin-Zhi Wei, Xue-Liang Wang, Xiao-Jun Sun, Yan Hou, Xin Zhang, Dou-Dou Yang, Hong Dong, Feng-Ming Zhang
Rapid and large-scale synthesis of metal-organic frameworks (MOFs) materials is of great significance for their practical applications. For the first time, we have electrochemically synthesized IRMOF-3 at room temperature by applying a voltage to a zinc electrode immersed in electrolyte containing 2-aminoterephthalic acid (NH2 -H2 BDC). The reaction conditions, including the ratio of solvent (electrolyte), the applied voltage, and different reaction times, were investigated and optimized. The degree of crystallinity and nanomorphology of the synthesized IRMOF-3 can be controlled by changing the reaction conditions...
March 12, 2018: Inorganic Chemistry
Prasad G Mahajan, Nilam C Dige, Netaji K Desai, Shivajirao R Patil, Vijay V Kondalkar, Seong-Karp Hong, Ki Hwan Lee
Nowadays scientist over the world are engaging to put forth improved methods to detect metal ion in an aqueous medium based on fluorescence studies. A simple, selective and sensitive method was proposed for detection of Co2+ ion using fluorescent organic nanoparticles. We synthesized a fluorescent small molecule viz. 4,4'-{benzene-1,4-diylbis-[(Z)methylylidenenitrilo]}dibenzoic acid (BMBA) to explore its suitability as sensor for Co2+ ion and biocompatibility in form of nanoparticles. Fluorescence nanoparticles (BMBANPs) prepared by simple reprecipitation method...
March 3, 2018: Spectrochimica Acta. Part A, Molecular and Biomolecular Spectroscopy
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