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Metal enhanced fluorescence

Xingxing Zhang, Haiyun Rui, Fenqin Zhang, Zhubing Hu, Yan Xia, Zhenguo Shen
Phytochelatins (PCs) catalyzed by phytochelatin synthases (PCS) are important for the detoxification of metals in plants and other living organisms. In this study, we isolated a PCS gene ( VsPCS1 ) from Vicia sativa and investigated its role in regulating cadmium (Cd) tolerance. Expression of VsPCS1 was induced in roots of V. sativa under Cd stress. Analysis of subcellular localization showed that VsPCS1 was localized in the cytoplasm of mesophyll protoplasts of V. sativa . Overexpression of VsPCS1 ( 35S::VsPCS1 , in wild-type background) in Arabidopsis thaliana could complement the defects of Cd tolerance of AtPCS1 -deficent mutant ( atpcs1 )...
2018: Frontiers in Plant Science
Niansheng Wang, Renjie Wang, Yayi Tu, Shouzhi Pu, Gang Liu
A novel photochromic diarylethene with a triazole-containing 2-(2'-phenoxymethyl)-benzothiazole group has been synthesized via "click" reaction. The diarylethene exhibited good photochromism and photoswitchable fluorescence. Its fluorescence emission intensity was enhanced 7-fold by acids, accompanied by the red-shift of emission peak from 526nm to 566nm and the concomitant color change from dark to bright flavogreen. The diarylethene selectively formed a 1:1 metal complex with Al3+ , resulting in a "turn-on" fluorescence signal...
February 6, 2018: Spectrochimica Acta. Part A, Molecular and Biomolecular Spectroscopy
Hang Ren, Ya-Ting Su, Xiao-Hua Guo
Some optimization techniques have been widely applied for spore fermentation based on the plate counting. This study optimized the culture medium for the spore production of Bacillus amyloliquefaciens BS-20 and investigated the feasibility of using a dipicolonic acid (DPA) fluorimetry assay as a simpler alternative to plate counting for evaluating spore yields. Through the single-factor experiment, the metal ions and agro-industrial raw materials that significantly enhanced spore production were determined...
February 16, 2018: AMB Express
Minsu Kim, Kangwon Lee, Ji Eon Kwon, Won Gun Koh
In this study, we developed an enzyme-based miniaturized fluorescence biosensor to detect paraoxon, one of the most well-known neurotoxic organophosphorus compounds (OPs). The biosensor was fabricated with poly(ethylene glycol) (PEG) hydrogel microarrays that entrapped acetylcholinesterase (AChE) and quantum dots (QDs) as fluorescence reporters. Metal-enhanced fluorescence (MEF) was utilized to amplify the fluorescence signal, which was achieved by decorating QDs on the surface of silica-coated silver nanoparticles (Ag@Silica)...
February 16, 2018: Biofabrication
Ján Kovác, Alexander Lux, Marek Vaculík
Background and Aims: Heavy metals induce changes in root metabolism and physiology, which can lead to a complex remodelling of the root system. The final morphological responses of radish (Raphanus sativus) roots exposed to toxic concentrations of the heavy metal (Cu) include root growth inhibition, differentiation of xylem vessels close to the root tip, enhanced suberin lamellae deposition and enhanced lateral root production. Recently, we have found that such changes in root morphology and anatomy are coupled to the formation of a subero-lignified apical deposit (SLAD) very close to the root tip...
February 10, 2018: Annals of Botany
Qi Luo, Xueshuang Deng, Wenhan Chen, Hai Guo, Wei Ou-Yang, Xiaohong Chen, Sumei Huang
We report a simple method for the fabrication of a three-layered plasmonic structure of silicon substrate-Au nanospheres-upconversion particles (UCNPs) that displays up to 101-fold fluorescence enhancement. Monodispersed pure hexagonal-phase NaYF4:Yb,Er core and NaYF4:Yb,Er@NaYF4 core@shell nanocrystals were prepared by a solvothermal method. Two dimensional (2D) assembled Au spheres were prepared on a Si substrate, and then, 2D arrays of UCNPs were deposited on the grown 2D monolayered Au spheres by a self-organizing process...
July 1, 2018: Journal of Nanoscience and Nanotechnology
Maniya Gharib, Vahid Safarifard, Ali Morsali
Nano plates of zinc(II) based metal-organic framework (MOF) were prepared via ultrasonic method without any surfactants at room temperature and atmospheric pressure. Control of particle size and morphology was enhanced in this synthesis method. Nano plates of an interpenetrated amide-functionalized metal-organic framework, [Zn2(oba)2(bpfb)]·(DMF)5, TMU-23, (H2oba = 4,4'-oxybis(benzoic acid); bpfb = N,N'-bis-(4-pyridylformamide)-1,4-benzenediamine, DMF = N,N-dimethyl formamide), was synthesized under ultrasound irradiation in different concentrations of initial precursor...
April 2018: Ultrasonics Sonochemistry
Tuğba Köker, Nathalie Tang, Chao Tian, Wei Zhang, Xueding Wang, Richard Martel, Fabien Pinaud
The in cellulo assembly of plasmonic nanomaterials into photo-responsive probes is of great interest for many bioimaging and nanophotonic applications but remains challenging with traditional nucleic acid scaffolds-based bottom-up methods. Here, we address this quandary using split-fluorescent protein (FP) fragments as molecular glue and switchable Raman reporters to assemble gold or silver plasmonic nanoparticles (NPs) into photonic clusters directly in live cells. When targeted to diffusing surface biomarkers in cancer cells, the NPs self-assemble into surface-enhanced Raman-scattering (SERS) nanoclusters having hot spots homogenously seeded by the reconstruction of full-length FPs...
February 9, 2018: Nature Communications
Jeremy B Essner, Xi Chen, Troy D Wood, Gary A Baker
We report a sensory platform for the determination of common explosive species (e.g., TNT, PETN, RDX) based on the differential response from two different luminescent metal nanoclusters. In particular, whereas the red emission from bovine serum albumin-protected gold nanoclusters was strongly quenched by nitro-, nitrate-, and nitroamine-containing explosive organic molecules, blue-emitting glutathione-capped copper nanoclusters proved inert to quenching by these same analytes, instead showing evidence for aggregation-induced emission enhancement (AIEE)...
February 9, 2018: Analyst
Shao-Jun He, Yu-Wen Xie, Qiu-Yun Chen
In order to develop NIR BODIPY for mitochondria targeting imaging agents and metal sensors, a side chain modified BODIPY (BPN) was synthesized and spectroscopically characterized. BPN has NIR emission at 765nm when excited at 704nm. The emission at 765nm responded differently to Cu2+ and Mn2+ ions, respectively. The BPN coordinated with Cu2+ forming [BPNCu]2+ complex with quenched emission, while Mn2+ induced aggregation of BPN with specific fluorescence enhancement. Moreover, BPN can be applied to monitor Cu2+ in live cells and image mitochondria...
February 1, 2018: Spectrochimica Acta. Part A, Molecular and Biomolecular Spectroscopy
N Harikrishnan, A Chandrasekaran, R Ravisankar, R Alagarsamy
A rapid urbanization and industrialization enhances the significant heavy metal pollution in the sediments of coastal area and introduced a serious threat to the human health. In the present study, concentration of heavy metals such as Al, Ti, Fe, V, Cr, Mn, Co, Zn, La, Pb, Mg, Ca, Ni, Cd and Ba are determined in sediments along Periyakalapet to Parangaipettai coastal area, Tamilnadu using energy dispersive X-ray fluorescence spectrometer (EDXRF).These metals have more affinity to establish metallic bond with ferrous material leading to enhancement of sediment magnetic susceptibility...
January 31, 2018: Applied Radiation and Isotopes
Mark T Agasid, Xuemin Wang, Yiding Huang, Colleen M Janczak, Robert Branström, S Scott Saavedra, Craig A Aspinwall
The inwardly rectifying K+ (Kir) channel, Kir6.2, plays critical roles in physiological processes in the brain, heart, and pancreas. Although Kir6.2 has been extensively studied in numerous expression systems, a comprehensive description of an expression and purification protocol has not been reported. We expressed and characterized a recombinant Kir6.2, with an N-terminal decahistidine tag, enhanced green fluorescent protein (eGFP) and deletion of C-terminal 26 amino acids, in succession, denoted eGFP-Kir6...
January 30, 2018: Protein Expression and Purification
Chan Yang, Xia Yin, Shuang-Yan Huan, Lanlan Chen, Xiao-Xiao Hu, Mengyi Xiong, Kun Chen, Xiao-Bing Zhang
RNA-cleaving DNAzymes have been demonstrated as a promising platform for sensing metal ions. However, the poor biological imaging performance of RNA cleaving DNAzyme-based fluorescent probes has limited their intracellular applications. Compared with traditional one photon fluorescence imaging, two photon (TP) fluorescent probes have shown advantages such as increased penetration depth, lower tissue autofluorescence, and reduced photo damage. Herein, for the first time, we developed a RNA-cleaving DNAzyme-based TP imaging probe (TP-8-17ES-AuNP) for Zn2+ detection in living cells by modifying Zn2+-specific DNAzyme (8-17) with TP fluorophore (TP-8-17ES), and using gold nanoparticles (AuNPs) for intracellular delivery...
February 7, 2018: Analytical Chemistry
Ravi Pamu, Venkatanarayana Prasad Sandireddy, Ramki Kalyanaraman, Bamin Khomami, Dibyendu Mukherjee
Plasmonic metal nanostructures have been known to tune optoelectronic properties of fluorophores. To this end, we report the first-ever experimental observation of plasmon-induced photocurrent enhancements from Photosystem I (PSI) attached to Fischer patterns of silver nano-pyramids (Ag-NP) whose resonance peaks are tuned to match the PSI absorption peaks at ~450 and ~680 nm. The plasmon enhanced photocurrents indicate enhancement factors of ~6.5 and ~5.8 as compared to PSI assembly on planar Ag substrates for nominal excitation wavelengths of 660 and 470 nm respectively...
February 6, 2018: Journal of Physical Chemistry Letters
Amir Karamlou, Matthew E Trusheim, Dirk Englund
A central challenge in quantum technologies based on atom-like defects is the efficient collection of the emitter's fluorescence. Optical antennas are appealing as they offer directional emission together with spontaneous emission rate enhancement across a broad emitter spectrum. In this work, we introduce and optimize metal-dielectric nanoantenna designs recessed into a diamond substrate and aligned with quantum emitters. We analyze tradeoffs between external quantum efficiency, collection efficiency, radiative Purcell factor, and overall collected photon rate...
February 5, 2018: Optics Express
Han Pill Song, Yongil Lee, Vu Khac Hoang Bui, You-Kwon Oh, Hyun Gyu Park, Moon Il Kim, Young-Chul Lee
In this study, we describe a novel peroxidase-like activity of Co-aminoclay [CoAC] present at pH ~5.0 and its application to fluorescent biosensor for the determination of H₂O₂ and glucose. It is synthesized with aminoclays (ACs) entrapping cationic metals such as Fe, Cu, Al, Co., Ce, Ni, Mn, and Zn to find enzyme mimicking ACs by sol-gel ambient conditions. Through the screening of catalytic activities by the typical colorimetric reaction employing 2,2'-azino-bis(3-ethylbenzo-thiazoline-6-sulfonic acid)diammonium salt (ABTS) as a substrate with or without H₂O₂, Fe, Cu, and CoACs are found to exhibit peroxidase-like activity, as well as oxidase-like activity was observed from Ce and MnACs...
February 3, 2018: Sensors
Zahra Naeimi, MirFaez Miri
We show that fractal clusters of hollow Si nanoparticles provide both magnetic hotspots (MHs) and electric hotspots (EHs). The hollow size tailors the wavelength dependence of the field enhancement. In the wavelength window 400-750 nm, magnetic field intensity enhancements of 10-3790 and electric field intensity enhancements of 10-400 are achievable. Wavelength-tuned MHs and EHs allow better enhancement of Raman optical activity, fluorescence and circular dichroism of molecules, and so on. Si nanoparticles overcome the limitations of metallic ones, which provide only EHs at the price of heat perturbations on a nearby quantum emitter due to metallic ohmic losses...
February 1, 2018: Optics Letters
Yong Wei, Li Li, De-Xian Sun, Ming-Li Wang, Yan-Ying Zhu
In the present work we study the surface-enhanced resonant Raman scattering (SERRS) and fluorescence (SEF) spectra of a general model molecule confined in metallic dimers consisting of Ag, Au and hybrid AuAg nanoparticles (NPs). The electromagnetic (EM) enhancement factors were simulated by the generalized Mie scatting method and the scattering cross section of the molecules were obtained by density-matrix calculations. The influence of the size of the NPs and the separation between the dimer on the Raman scattering and fluorescence were systematically studied and analyzed in detail...
January 30, 2018: Scientific Reports
Zhen Cao, Yu Zhu, Yang Liu, Shurong Dong, Xin Chen, Fan Bai, Shengxin Song, Junxue Fu
A nanoscale insulator-based dielectrophoresis (iDEP) technique is developed for rapid enrichment of proteins and highly sensitive immunoassays. Dense arrays of nanorods (NDs) by oblique angle deposition create a super high electric field gradient of 2.6 × 1024 V2 m-3 and the concomitant strong dielectrophoresis force successfully traps small proteins at a bias as low as 5 V. 1800-fold enrichment of bovine serum albumin protein at a remarkable rate of up to 180-fold s-1 is achieved using oxide coated Ag nanorod arrays with pre-patterned sawtooth electrodes...
January 26, 2018: Small
He He, Yi Lin, Zhi-Quan Tian, Dong-Liang Zhu, Zhi-Ling Zhang, Dai-Wen Pang
Ag2 S quantum dots (QDs) are well-known near-infrared fluorophores and have attracted great interest in biomedical labeling and imaging in the past years. However, their photoluminescence efficiency is hard to compete with Cd-, Pb-based QDs. The high Ag+ mobility in Ag2 S crystal, which causes plenty of cation deficiency and crystal defects, may be responsible mainly for the low photoluminescence quantum yield (PLQY) of Ag2 S QDs. Herein, a cation-doping strategy is presented via introducing a certain dosage of transition metal Pb2+ ions into Ag2 S nanocrystals to mitigate this intrinsic shortcoming...
January 29, 2018: Small
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