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https://www.readbyqxmd.com/read/28544970/quantitative-chemical-imaging-with-stimulated-raman-scattering-microscopy
#1
REVIEW
Dan Fu
Chemical imaging plays an increasingly important role in studying heterogeneous biological systems. It combines molecular spectroscopy with high-resolution spatial information to create quantitative images of molecular distributions. Here I summarize recent progress in technical developments and biological applications of a specific chemical imaging technique-stimulated Raman scattering (SRS) microscopy. SRS microscopy allows for a wide range of molecules - both endogenous and exogenous - to be imaged at high spatial and temporal resolution in living cells, tissues, and organisms...
May 22, 2017: Current Opinion in Chemical Biology
https://www.readbyqxmd.com/read/28544849/co-catalytic-effects-of-cos2-on-activity-of-mos2-catalyst-for-electrochemical-hydrogen-evolution
#2
Ranjith Bose, Zhenyu Jin, Seokhee Shin, Sungjoon Kim, Sun Young Lee, Yo-Sep Min
MoS2 is a promising material to replace Pt catalyst for electrochemical hydrogen evolution reaction (HER). It is well known that the activity of the MoS2 catalyst in the HER is significantly promoted by doping cobalt atoms. Recently, the Co-Mo-S phase, in which cobalt atoms decorate the edge positions of the MoS2 slabs, has been identified as a co-catalytic phase in the Co-doped MoS2 (Co-MoSx) with a low Co content. Here, we report the effect of the incorporation of cobalt atoms on the chemical state of Co-MoSx catalyst which gives rise to the co-catalytic effect...
May 25, 2017: Langmuir: the ACS Journal of Surfaces and Colloids
https://www.readbyqxmd.com/read/28543748/universal-method-for-large-scale-synthesis-of-layered-transition-metal-dichalcogenides
#3
Zdenek Sofer, David Sedmidubsky, Jan Luxa, Daniel Bousa, Stepan Huber, Petr Lazar, Martin Vesely, Martin Pumera
The layered transition metal dichalcogenides currently belong to the most intensively investigated materials. These com-pounds constitute a broad family of materials with characteristic layered structures and covering both semiconductors and metallic materials. The great attention arises from the possibility to exfoliate these materials down to single layers with many unique properties like thickness dependent energy of band gap and the possibility of tuning transport properties by phase transitions. The research in the field of transition metal dichalcogenides is also motivated by their high electrocatalytic activity towards several industrially important reactions like hydrogen evolution reaction as well as many other applications in nano- and optoelectronics...
May 20, 2017: Chemistry: a European Journal
https://www.readbyqxmd.com/read/28543094/mechanism-of-graphene-induced-cytotoxicity-role-of-endonucleases
#4
Tariq Fahmi, La Donna Branch, Zeid A Nima, Dae Song Jang, Alena V Savenka, Alexandru S Biris, Alexei G Basnakian
Graphene, a crystalline allotrope or carbon, presents numerous useful properties; however, its toxicity is yet to be determined. One of the most dramatic and irreversible toxic abilities of carbon nanomaterials is the induction of DNA fragmentation produced by endogenous cellular endonucleases. This study demonstrated that pristine graphene exposed to cultured kidney tubular epithelial cells is capable of inducing DNA fragmentation measured by terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) assay, which is usually associated with cell death...
May 24, 2017: Journal of Applied Toxicology: JAT
https://www.readbyqxmd.com/read/28542238/frutexites-like-structures-formed-by-iron-oxidizing-biofilms-in-the-continental-subsurface-%C3%A3-sp%C3%A3-hard-rock-laboratory-sweden
#5
Christine Heim, Nadia-Valérie Quéric, Danny Ionescu, Nadine Schäfer, Joachim Reitner
Stromatolitic iron-rich structures have been reported from many ancient environments and are often described as Frutexites, a cryptic microfossil. Although microbial formation of such structures is likely, a clear relation to a microbial precursor is lacking so far. Here we report recent iron oxidizing biofilms which resemble the ancient Frutexites structures. The living Frutexites-like biofilms were sampled at 160 m depth in the Äspö Hard Rock Laboratory in Sweden. Investigations using microscopy, 454 pyrosequencing, FISH, Raman spectroscopy, biomarker and trace element analysis allowed a detailed view of the structural components of the mineralized biofilm...
2017: PloS One
https://www.readbyqxmd.com/read/28541929/pressure-induced-structural-modifications-of-rare-earth-hafnate-pyrochlore
#6
Katlyn M Turner, Dylan R Rittman, Rachel A Heymach, Cameron L Tracy, Madison L Turner, Antonio F Fuentes, Wendy L Mao, Rodney C Ewing
Complex oxides with the pyrochlore (A2B2O7) and defect-fluorite ((A,B)4O7) structure-types undergo structural transformations under high-pressure. Rare-earth hafnates (A2Hf2O7) form the pyrochlore structure for A  =  La-Tb and the defect-fluorite structure for A  =  Dy-Lu. High-pressure transformations in A2Hf2O7 pyrochlore (A  =  Sm, Eu, Gd) and defect-fluorite (A  =  Dy, Y, Yb) were investigated up to ~50 GPa and characterized by in situ Raman spectroscopy and synchrotron x-ray diffraction (XRD)...
May 25, 2017: Journal of Physics. Condensed Matter: An Institute of Physics Journal
https://www.readbyqxmd.com/read/28541708/highly-stable-monocrystalline-silver-clusters-for-plasmonic-applications
#7
Sergey M Novikov, Vladimir N Popok, Andrey B Evlyukhin, Muhammad Hanif, Per Morgen, Jacek Fiutowski, Jonas Beermann, Horst-Guenter Rubahn, Sergey I Bozhevolnyi
: Plasmonics sensor configurations utilizing localized plasmon resonances in silver nanostructures typically suffer from rapid degradation of silver in ambient atmospheric conditions. In this work, we report on the fabrication and detailed characterization of ensembles of monocrystalline silver nanoparticles (NPs), which exhibit a long-term stability of optical properties under ambient conditions without any protective treatments. Ensembles with different densities (surface coverages) of size-selected NPs (diameters from 12...
May 25, 2017: Langmuir: the ACS Journal of Surfaces and Colloids
https://www.readbyqxmd.com/read/28541698/a-sensitive-phonon-based-probe-for-structure-identification-of-1t-mote2
#8
Lin Zhou, Shengxi Huang, Yuki Tatsumi, Lijun Wu, Huaihong Guo, Yaqing Bie, Keiji Ueno, Teng Yang, Yimei Zhu, Jing Kong, Riichiro Saito, Mildred S Dresselhaus
In this work, by combining transmission electron microscopy and polarized Raman spectroscopy for the 1T' MoTe2 flakes with different thicknesses, we found that the polarization dependence of Raman intensity is given as a function of excitation laser wavelength, phonon symmetry and phonon frequency, but has weak dependence on the flake thickness from few-layer to multilayer. In addition, the frequency of Raman peaks and the relative Raman intensity are sensitive to flake thickness, which manifests Raman spectroscopy as an effective probe for thickness of 1T' MoTe2...
May 25, 2017: Journal of the American Chemical Society
https://www.readbyqxmd.com/read/28541692/stable-chloro-and-bromoxenate-cage-anions-x3-xeo3-3-3-and-x4-xeo3-4-4-x-cl-or-br
#9
James T Goettel, Veit Haensch, Gary J Schrobilgen
The number of isolable compounds which contain different noble-gas-element bonds is limited for xenon and even more so for krypton. Examples of Xe-Cl bonds are rare and prior to this work, no definitive evidence for a Xe-Br bonded compound existed. The syntheses, isolation, and characterization of the first compounds to contain Xe-Br bonds and their chlorine analogues are described in the present work. The reactions of XeO3 with [N(CH3)4]Br and [N(C2H5)4]Br have provided two bromoxenate salts, [N(C2H5)4][Br3(XeO3)3] and [N(CH3)4][Br4(XeO3)4], in which the cage anions have Xe-Br bond lengths that range from 3...
May 25, 2017: Journal of the American Chemical Society
https://www.readbyqxmd.com/read/28541350/ultrasensitive-and-reproducible-sers-platform-of-coupled-ag-grating-with-multibranched-au-nanoparticles
#10
Yevgeniya Kalachyova, David Mares, Vitezslav Jerabek, Pavel Ulbrich, Ladislav Lapcak, Vaclav Svorcik, Oleksiy Lyutakov
Surface-enhanced Raman scattering (SERS) spectroscopy is an extremely sensitive analytical technique that is capable of identifying the vibration signatures of target molecules up to single-molecule sensitivity. In this work, the ultrahigh sensitivity of SERS has been achieved through the immobilization of sharp-edges specific nanoparticles - so-called gold multibranched NPs (AuMs) on the silver grating surface through the biphenyl dithiol. This approach allows combining the extremely high SERS enhancement factor (better than that in the case of AuMs immobilized on the flat Ag film) with perfect reproducibility of Raman signals...
May 25, 2017: Physical Chemistry Chemical Physics: PCCP
https://www.readbyqxmd.com/read/28541053/anomalous-non-linear-optical-response-of-graphene-near-phonon-resonances
#11
Lucas Lafetá, Alisson Ronieri Cadore, Thiago Grasiano Mendes-de-Sa, Kenji Watanabe, Takashi Taniguchi, Leonardo Cristiano Campos, Ado Jorio, Leandro M Malard
In this work we probe the third-order non-linear optical property of graphene, hexagonal boron nitride and their heterostructure by the use of coherent anti-Stokes Raman Spectroscopy. When the energy difference of the two input fields match the phonon energy, the anti-Stokes emission intensity is enhanced in h-BN, as usually expected while for graphene an anomalous decrease is observed. This behaviour can be understood in terms of a coupling between the electronic continuum and a discrete phonon state. We have also measured a graphene/h-BN heterostructure and demonstrate that the anomalous effect in graphene dominates the heterostructure non-linear optical response...
May 25, 2017: Nano Letters
https://www.readbyqxmd.com/read/28541037/phase-behavior-of-salt-free-polyelectrolyte-gel-surfactant-systems
#12
Martin Andersson, Per Hansson
Ionic surfactants tend to collapse the outer parts of polyelectrolyte gels, forming shells that can be used to encapsulate other species including protein and peptide drugs. In this paper the aqueous phase behaviour of covalently crosslinked polyacrylate networks containing sodium ions and dodecyltrimethylammonium ions as counterions is investigated by means of swelling isotherms, dye staining, small-angle x-ray scattering and confocal Raman spectroscopy. The equilibrium state is approached by letting the networks absorb pure water...
May 25, 2017: Journal of Physical Chemistry. B
https://www.readbyqxmd.com/read/28541036/non-invasive-diagnosis-of-high-grade-urothelial-carcinoma-in-urine-by-raman-spectral-imaging
#13
Hesham K Yosef, Sascha D Krauß, Tatjana Lechtonen, Hendrik Jütte, Andrea Tannapfel, Heiko Udo Käfferlein, Thomas Brüning, Florian Roghmann, Joachim Noldus, Axel Mosig, Samir F El-Mashtoly, Klaus Gerwert
The current gold standard for diagnosis of bladder cancer is cystoscopy, which is an invasive and painful for patients. Therefore, the non-invasive urine cytology is usually used in clinics as an adjunct to cystoscopy. However, it suffers from low sensitivity. Here, a novel non-invasive, label-free approach on urine is presented with high sensitivity. CARS imaging of urine sediments was used in the first step for fast preselection of urothelial cells, where, the high-grade urothelial cancer cells are characterized by a large nucleus to cytoplasm ratio...
May 25, 2017: Analytical Chemistry
https://www.readbyqxmd.com/read/28541032/exosome-classification-by-pattern-analysis-of-surface-enhanced-raman-spectroscopy-data-for-lung-cancer-diagnosis
#14
Jaena Park, Miyeon Hwang, ByeongHyeon Choi, Hyesun Jeong, Jik-Han Jung, Hyun Koo Kim, Sunghoi Hong, Ji Ho Park, Yeonho Choi
Owing to the role of exosome as a cargo for intercellular communication, especially in cancer metastasis, the evidence has been consistently accumulated that exosomes can be used as a non-invasive indicator of cancer. Consequently, several studies applying exosome have been proposed for cancer diagnostic methods such as ELISA assay. However, it has been still challenging to get reliable results due to the requirement of a labeling process and high concentration of exosome. Here, we demonstrate a label-free and highly sensitive classification method of exosome by combining surface enhanced Raman scattering (SERS) and statistical pattern analysis...
May 25, 2017: Analytical Chemistry
https://www.readbyqxmd.com/read/28540461/quantitative-analysis-of-curcumin-loaded-alginate-nanocarriers-in-hydrogels-using-raman-and-attenuated-total-reflection-infrared-spectroscopy
#15
Lynda Miloudi, Franck Bonnier, Dominique Bertrand, Hugh J Byrne, Xavier Perse, Igor Chourpa, Emilie Munnier
Core-shell nanocarriers are increasingly being adapted in cosmetic and dermatological fields, aiming to provide an increased penetration of the active pharmaceutical or cosmetic ingredients (API and ACI) through the skin. In the final form, the nanocarriers (NC) are usually prepared in hydrogels, conferring desired viscous properties for topical application. Combined with the high chemical complexity of the encapsulating system itself, involving numerous ingredients to form a stable core and quantifying the NC and/or the encapsulated active without labor-intensive and destructive methods remains challenging...
May 25, 2017: Analytical and Bioanalytical Chemistry
https://www.readbyqxmd.com/read/28538680/diazonium-salt-based-surface-enhanced-raman-spectroscopy-nanosensor-detection-and-quantitation-of-aromatic-hydrocarbons-in-water-samples
#16
Inga Tijunelyte, Stéphanie Betelu, Jonathan Moreau, Ioannis Ignatiadis, Catherine Berho, Nathalie Lidgi-Guigui, Erwann Guénin, Catalina David, Sébastien Vergnole, Emmanuel Rinnert, Marc Lamy de la Chapelle
Here, we present a surface-enhanced Raman spectroscopy (SERS) nanosensor for environmental pollutants detection. This study was conducted on three polycyclic aromatic hydrocarbons (PAHs): benzo[a]pyrene (BaP), fluoranthene (FL), and naphthalene (NAP). SERS substrates were chemically functionalized using 4-dodecyl benzenediazonium-tetrafluoroborate and SERS analyses were conducted to detect the pollutants alone and in mixtures. Compounds were first measured in water-methanol (9:1 volume ratio) samples. Investigation on solutions containing concentrations ranging from 10(-6) g L(-1) to 10(-3) g L(-1) provided data to plot calibration curves and to determine the performance of the sensor...
May 24, 2017: Sensors
https://www.readbyqxmd.com/read/28538206/spectroscopic-far-or-terahertz-mid-infrared-and-raman-investigation-thermal-analysis-and-biological-activity-of-piplartine
#17
Anubha Srivastava, T Karthick, B D Joshi, Rashmi Mishra, Poonam Tandon, A P Ayala, Javier Ellena
Research in the field of medicinal plants including Piper species like long pepper (Piper longum L.- Piperaceae) is increasing all over the world due to its use in traditional and Ayurvedic medicine. Piplartine (piperlongumine, 5,6-dihydro-1-[(2E)-1-oxo-3-(3,4,5-trimethoxyphenyl)-2-propenyl]-2(1H)-pyridinone), a biologically active alkaloid/amide was isolated from the phytochemical investigations of Piper species, as long pepper. This alkaloid has cytotoxic, anti-fungal, anti-diabetic, anti-platelet aggregation, anti-tumoral, anxiolytic, anti-depressant, anti-leishmanial, and genotoxic activities, but, its anticancer property is the most promising and has been widely explored...
May 5, 2017: Spectrochimica Acta. Part A, Molecular and Biomolecular Spectroscopy
https://www.readbyqxmd.com/read/28538102/effects-of-wet-blending-on-detection-of-melamine-in-spray-dried-lactose
#18
Betsy Jean Yakes, Marti M Bergana, Peter F Scholl, Magdi M Mossoba, Sanjeewa R Karunathilaka, Luke K Ackerman, Jason D Holton, Boyan Gao, Jeffrey C Moore
During the development of rapid screening methods to detect economic adulteration, spray-dried milk powders prepared by dissolving melamine in liquid milk exhibited an unexpected loss of characteristic melamine features in the NIR and Raman spectra. To further characterize this "wet-blending" phenomenon, spray-dried melamine and lactose samples were produced as a simplified model and investigated by near-infrared spectroscopy, Raman spectroscopy, 1H NMR, and DART-FTMS. In contrast to dry-blended samples, characteristic melamine bands in NIR and Raman spectra disappeared or shifted in wet-blended lactose-melamine samples...
May 24, 2017: Journal of Agricultural and Food Chemistry
https://www.readbyqxmd.com/read/28537308/catalytically-active-ceria-supported-cobalt-manganese-oxide-nanocatalysts-for-oxidation-of-carbon-monoxide
#19
Xu Wang, Lin-Ying Du, Meng Du, Chao Ma, Jie Zeng, Chun-Jiang Jia, Rui Si
A low-concentration cobalt (∼6 at%) and manganese (∼3 at%) bimetallic oxide catalyst supported on ceria nanorods (CoMnOx/CeO2), as well as its related single metal oxide counterparts (CoOx/CeO2 and MnOx/CeO2) was synthesized via a deposition-precipitation approach. The fresh samples after air-calcination at 400 °C were tested under the reaction conditions of CO oxidation, and showed the following order of reactivity: CoMnOx/CeO2 > CoOx/CeO2 > MnOx/CeO2. X-ray diffraction (XRD) and transmission electron microscopy (TEM) data identified that the structure of the CeO2 support was maintained during deposition of metal (Co, Mn) ions while the corresponding vis-Raman spectra verified that more oxygen vacancies were created after deposition-precipitation than those in pure ceria nanorods...
May 24, 2017: Physical Chemistry Chemical Physics: PCCP
https://www.readbyqxmd.com/read/28537294/using-raman-spectroscopy-to-assess-hemoglobin-oxygenation-in-red-blood-cell-concentrate-an-objective-proxy-for-morphological-index-to-gauge-the-quality-of-stored-blood
#20
Chad G Atkins, H Georg Schulze, Deborah Chen, Dana V Devine, Michael W Blades, Robin F B Turner
Blood banking is an essential aspect of modern medical care. When red blood cells (RBCs) are stored, they become damaged by various chemical processes, such as accumulation of their own waste products and oxidative injury, among others. These processes lead to the development of the RBC storage lesion, a complex condition where the severity is reflected through the morphology of the stored cells. It was hypothesized that Raman spectroscopy could be used to monitor certain structural and compositional changes associated with such ageing effects and that a relationship between these features and traditional morphology (as measured using a morphology index) could be observed...
May 24, 2017: Analyst
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