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raman imaging

Hua-Ying Chen, Dan Guo, Zhen-Fei Gan, Lei Jiang, Shuai Chang, Da-Wei Li
A surface-enhanced Raman scattering (SERS) based nanoprobe was developed for detection and imaging of endogenous peroxynitrite in living cells. The probe was fabricated by assembling 3-mercaptophenylboronic acid pinacol ester onto the surface of gold nanoparticles (AuNPs). The detection of peroxynitrite is accomplished via measurement of the changes in the SERS spectra (at 882 cm-1 ) that are caused by the reaction between probe and peroxynitrite. The probe has a fast response (<30 s), a 0.4 μM lower detection limit and a wide linearity range from 5...
December 10, 2018: Mikrochimica Acta
Kamalesh Chaudhari, Tripti Ahuja, Vasanthanarayan Murugesan, Vidhya Subramanian, Mohd Azhardin Ganayee, Thomas Thundat, Thalappil Pradeep
We report simultaneous plasmonic scattering and Raman spectroscopic observations of single citrate capped silver nanoparticles (AgNPs) which exhibit surface enhanced Raman scattering (SERS) upon meeting specific conditions induced by laser (532 nm) exposure. We show that nanoparticles which are not initially SERS active become SERS active by laser-induced reshaping/reorientation. A set-up developed for these observations enabled in situ high speed time-lapse characterization using plasmonic and Raman spectroscopies in conjunction with dark-field microscopy (DFM)...
December 11, 2018: Nanoscale
Chanda Gupta, Roy Tan, Chitaranjan Mishra, Neha Khandelwal, Rajiv Raman, Ramasamy Kim, Rupesh Agrawal, Parveen Sen
PURPOSE: To evaluate structural changes in the choroid among patients with diabetic macular edema (DME), with varying grades of diabetic retinopathy (DR), using enhance depth imaging spectral domain optical coherence tomography (EDI SD-OCT) scans. METHODS: A cross-sectional study was conducted on 82 eyes with DR and DME and 86 healthy control eyes. Eyes with DME were classified according to the severity of DR as per the international DR severity scale. Sub foveal choroidal thickness (SFCT)was obtained using EDI SD-OCT scans...
2018: PloS One
Ting Wang, Alan R Potts, Stephen W Hoag
The objective of this study is to investigate the variability in physiochemical and spectral properties of commercially available vegetable grade Magnesium Stearate (MgSt) samples, and to assess the correlation between physiochemical properties and near-infrared (NIR) and Raman spectroscopic features to determine if fast spectral measurements could be used for physical and chemical evaluation. Thirteen MgSt samples of nine manufacturer grades were obtained from three suppliers. The chemical composition was examined using gas chromatography and loss on drying...
December 4, 2018: Journal of Pharmaceutical Sciences
Héctor Morillas, Maite Maguregui, Euler Gallego-Cartagena, Gladys Huallparimachi, Iker Marcaida, Isabel Salcedo, Luis F O Silva, Fernando Astete
Machu Picchu Inca sanctuary (Cusco Region, Peru) was constructed on a granitic plateau, better known as Vilcabamba batholith. One of the most important carved granitic rocks from this archaeological site is the Sacred Rock, used by Inca citizens for religious rituals. Due to the location and climatic conditions, different rocks from this archaeological site are affected by biocolonizations. Concretely, the Sacred Rock shows flaking and delamination problems. In this work, a non-destructive multi analytical methodology has been applied to determine the possible role of the biodeteriogens, forming the biological patina on the Sacred Rock, in the previously mentioned conservation problems...
November 22, 2018: Science of the Total Environment
Muriel Abbaci, Frederic De Leeuw, Ingrid Breuskin, Odile Casiraghi, Aïcha Ben Lakhdar, Wahib Ghanem, Corinne Laplace-Builhé, Dana Hartl
New optical technologies enhancing localization or assessing viability of parathyroid glands (PG) during endocrine surgery have been reported in clinical studies. These technologies could become complementary to the surgeon's eyes and may improve surgical outcomes in thyroidectomy and parathyroidectomy. Here, we conducted a systematic review focusing on PG identification and functional assessment using optical methods to enhance surgery. A systematic literature review was performed using MEDLINE and Embase database...
December 2018: Oral Oncology
Ashish Bhattarai, Kevin Thomas Crampton, Alan G Joly, Libor Kovarik, Wayne P Hess, Patrick Z El-Khoury
We image 4-mercaptobenzonitrile-functionalized silver nanowires (~20 nm diameter) through tip-enhanced Raman scattering (TERS). The enhanced local optical field-molecular interactions that govern the recorded hyperspectral TERS images are dissected through hybrid finite-difference time-domain-density functional theory simulations. Our forward simulations illustrate that the recorded spatio-spectral profiles of the chemically functionalized nanowires may be reproduced by accounting for the interaction between orientationally averaged molecular polarizability derivative tensors and enhanced incident/scattered local fields polarized along the tip axis...
December 5, 2018: Journal of Physical Chemistry Letters
Hang Zhai, Lijun Wang, Jörn Hövelmann, Lihong Qin, Wenjun Zhang, Christine V Putnis
Bioavailability and mobility of cadmium (Cd2+) and arsenate (As5+) in soils can be effectively lowered through the dissolution of brushite (dicalcium phosphate dihydrate, CaHPO4∙2H2O) coupled with the precipitation of a more stable mineral phase containing both Cd and As. Due to the ubiquitous presence of humic acid (HA) in soil environments, it is more complex to predict the fate of dissolved Cd and As during such sequestration. Here, we used in situ atomic force microscopy (AFM) to image the kinetics of simultaneous precipitation of Cd and As at the brushite-fluid interface in the presence of HA...
December 5, 2018: Environmental Science & Technology
Hui Liu, Jianfeng Wang, Jiachen Wang, Suping Cui
In this study, Multiwalled carbon nanotubes (MWCNTs) were oxidized by a mixture of sulfuric acid and nitric acid ( V : V = 3:1) at 70 °C for 1, 2, and 4 h, respectively. The oxidized MWCNTs were characterized by N₂ adsorption, Fourier-transform infrared spectroscopy (FT-IR), X-ray photoelectron spectroscopy (XPS), thermal gravimetric analysis (TGA), and Raman spectroscopy to determine the oxidation degree. The dispersion of the MWCNTs was investigated by UV-vis-NIR, SEM, and dynamic light scattering measurements...
December 2, 2018: Materials
Xuezhi Ma, Yangzhi Zhu, Ning Yu, Sanggon Kim, Qiushi Liu, Leonard Apontti, Da Xu, Ruoxue Yan, Ming Liu
The tip-enhanced Raman spectroscopy (TERS) imaging technique is designed to provide correlated morphological and chemical information with a nanoscale spatial resolution by utilizing the plasmonic resonance supported by metallic nanostructures at the tip apex of a scanning probe. However, limited by the scattering cross-sections of these nanostructures, only a small fraction of the incident light can be coupled to the plasmonic resonance to generate Raman signals. The uncoupled light then directly excites background spectra with a diffraction-limited resolution, which becomes the background noise that often blurs the TERS image...
December 4, 2018: Nano Letters
David C Johnson, Steven S Raman, Sohrab A Mirak, Lorna Kwan, Amirhossein M Bajgiran, William Hsu, Cleo K Maehara, Preeti Ahuja, Izak Faiena, Aydin Pooli, Amirali Salmasi, Anthony Sisk, Ely R Felker, David S K Lu, Robert E Reiter
BACKGROUND: Multiparametric magnetic resonance imaging (mpMRI) undoubtedly affects the diagnosis and treatment of localized prostate cancer (CaP). However, clinicians need a better understanding of its accuracy and limitations in detecting individual CaP foci to optimize management. OBJECTIVE: To determine the per-lesion detection rate for CaP foci by mpMRI and identify predictors of tumor detection. DESIGN, SETTING, AND PARTICIPANTS: We carried out a retrospective analysis of a prospectively managed database correlating lesion-specific results from mpMRI co-registered with whole-mount pathology (WMP) prostatectomy specimens from June 2010 to February 2018...
November 30, 2018: European Urology
Bikramjit Chatterjee, Asanka Jayawardena, Eric Heller, David W Snyder, Sarit Dhar, Sukwon Choi
The higher critical electric field of β-gallium oxide (Ga2 O3 ) gives promise to the development of next generation power electronic devices with improved size, weight, power, and efficiency over current state-of-the-art wide bandgap devices based on 4H-silicon carbide (SiC) and gallium nitride (GaN). However, it is expected that Ga2 O3 devices will encounter serious thermal issues due to the poor thermal conductivity of the material. In this work, self-heating in Ga2 O3 Schottky barrier diodes under different regimes of the diode operation was investigated using diverse optical thermography techniques including thermoreflectance thermal imaging, micro-Raman thermography, and infrared thermal microscopy...
November 2018: Review of Scientific Instruments
Christopher J Corden, Dustin W Shipp, Pavel Matousek, Ioan Notingher
We present a time-gated Raman micro-spectroscopy technique suitable for fast Raman mapping of samples eliciting large laser-induced fluorescence backgrounds. To achieve the required time resolution for effective fluorescence rejection, a picosecond pulsed laser and a single-photon avalanche diode were used. A module consisting of a spectrometer, digital micromirror device, and two prisms was used for high-resolution spectral filtering and multiplexing, which is required for a high chemical specificity and short integration times...
December 1, 2018: Optics Letters
Venkata Siva Gummaluri, S R Krishnan, C Vijayan
We demonstrate for the first time, to the best of our knowledge, Raman random lasing in a continuous-wave (CW) excited, completely biocompatible and biodegradable carrot medium naturally composed of fibrous cellulose scattering medium and rich carotene Raman gain medium. The CW-laser-induced photoluminescence threshold and linewidth analysis at the Stokes modes of carotene show a characteristic lasing action with a threshold of 130  W/cm2 and linewidth narrowing with mode Q factor up to 1300. Polarization study of output modes reveals that lasing mode mostly retains the source polarization state...
December 1, 2018: Optics Letters
Yu Su, Shuting Xu, Jinan Zhang, Xiang-Jian Chen, Li-Ping Jiang, Tingting Zheng, Jun-Jie Zhu
Cardiorenal syndrome (CRS) has posed tremendous challenges in patient management, and the detection of serum biomarkers may provide opportunities for early diagnosis and effective treatment. Herein, we introduce a novel surface-enhanced Raman scattering (SERS)-based sandwich immunoassay platform to simultaneously detect cardiac troponin I (cTnI), N-terminal prohormone of brain natriuretic peptide (NT-ProBNP) and neutrophil gelatinase-associated lipocalin (NGAL) for the early diagnosis of CRS by using Raman reporter molecules-labeled Ag-Au nanostars (Ag-Au NSs) as nanotags and three-dimensional ordered macroporous (3DOM) Au-Ag-Au plasmonic array as substrate...
November 30, 2018: Analytical Chemistry
Imke A K Fiedler, Michele Casanova, Tobias Keplinger, Björn Busse, Ralph Müller
Medical knowledge of the skeleton including its structures has improved constantly over the past decades. Advanced imaging methods, mechanical testing and optical techniques have revealed insights into bone architecture and composition. Most of these advancements were possible due to the ex vivo investigation of biological tissues. Investigations of fresh tissue are generally preferred over preserved or fixed samples. However, chemical fixation is sometimes inevitable due to histological procedures or logistical reasons...
November 2018: Journal of Biomedical Optics
Xuezhi Qiao, Zhenjie Xue, Lu Liu, Keyan Liu, Tie Wang
Although the strength of Raman signals can be increased by many orders of magnitude on noble metal nanoparticles, this enhancement is confined to an extremely short distance from the Raman-active surface. The key to the development of Raman spectroscopy for applications in diagnosis and detection of cancer and inflammatory diseases, and in pharmacology, relies on the capability of detecting analytes that are noninteractive with Raman-active surfaces. Here, a new Raman enhancement system is constructed, superficial-layer-enhanced Raman scattering (SLERS), by covering elongated tetrahexahedral gold nanoparticle arrays with a superficial perovskite (CH3 NH3 PbBr3 ) film...
November 28, 2018: Advanced Materials
Mengmeng Chen, Huanhuan Zhang, Yue Ge, Shuo Yang, Peijie Wang, Yan Fang
One-dimensional microscale SERS-active interfaces have been intriguing as a newly emerging class of SERS interfaces compared to conventional macroscale SERS substrates. In this work, a stable surface-nanostructured single silver nanowire was fabricated. The nanostructures on the nanowire are formed by nanoscale silver crystal dots with diameters of 20-50 nm. The SERS signals of the crystal violet probe molecules adsorbed on the nanostructures are dramatically enhanced by both electromagnetic and chemical effects...
November 28, 2018: Langmuir: the ACS Journal of Surfaces and Colloids
Lokesh Rana, Dinesh Sood, Raman Chauhan, Roshni Shukla, Pooja Gurnal, Himanshu Nautiyal, Manvendra Tomar
Background and purpose: Neonatal hypoxic-ischemic encephalopathy causes hypoxic brain injury. Due to differences in brain maturity at time of insult, severity of hypotension and duration of insult, there are four distinct patterns of brain injury. Magnetic resonance imaging is the most sensitive modality for evaluating these patterns of brain injury. Additional role of Diffusion weighted imaging and ADC values can be useful in the evaluation of such cases. We conducted this study to analyse the usefulness of ADC values in the brain tissue affected by hypoxic-ischemic injury...
2018: European Journal of Radiology Open
Uroš Puc, Andreja Abina, Anton Jeglič, Aleksander Zidanšek, Irmantas Kašalynas, Rimvydas Venckevičius, Gintaras Valušis
There is a need for fast and reliable quality and authenticity control tools of pharmaceutical ingredients. Among others, hormone containing drugs and foods are subject to scrutiny. In this study, terahertz (THz) spectroscopy and THz imaging are applied for the first time to analyze melatonin and its pharmaceutical product Circadin. Melatonin is a hormone found naturally in the human body, which is responsible for the regulation of sleep-wake cycles. In the THz frequency region between 1.5 THz and 4.5 THz, characteristic melatonin spectral features at 3...
November 23, 2018: Sensors
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