scholarly journals A Novel Polyaniline Nanofiber Combined with Toluidine Blue as a Sensitive Detection Platform for Lignin by Raman Spectroscopy

2021 ◽  
Vol 2021 ◽  
pp. 1-9
Author(s):  
Hui Zhang ◽  
Jing Li ◽  
Liang Zhou ◽  
Shengquan Liu
Keyword(s):  
Raman Spectroscopy ◽  
Toluidine Blue ◽  
Significant Contribution ◽  
Raman Signal ◽  
Specific Marker ◽  
Raman Intensity ◽  
Qualitative And Quantitative Analysis ◽  
Wood Science ◽  
Fluorescent Molecules ◽  
532 Nm

Raman spectroscopy is widely applied in wood science because of its features of being nondestructive, rapidity, and high resolution. However, Raman scattering is weak, and the Raman signal is easily disturbed by autofluorescence arising from endogenous fluorescent molecules in biological tissue. In this work, a sensitive lignin detection platform was fabricated by a composite with a polyaniline (PANI) nanofiber and toluidine blue (TB) under the excitation of visible light. In this platform, TB acts as a specific marker for lignin, and a PANI nanofiber was used as a reinforcing reagent to improve the Raman intensity of TB. When wood slice is impregnated with TB/PANI, the lignin in wood can be precisely labeled with the TB, and the Raman intensity of TB had a threefold increase at 532 nm excitation. This TB/PANI detection platform is expected to make a significant contribution in qualitative and quantitative analysis of lignin to avoid autofluorescence in various lignin-based biosciences.

scholarly journals Rapid uropathogen identification using surface enhanced Raman spectroscopy active filters

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Simon D. Dryden ◽  
Salzitsa Anastasova ◽  
Giovanni Satta ◽  
Alex J. Thompson ◽  
Daniel R. Leff ◽  
...  
Keyword(s):  
Raman Spectroscopy ◽  
Bacterial Infections ◽  
Surface Enhanced Raman Spectroscopy ◽  
Active Filters ◽  
Raman Signal ◽  
Rapid Diagnostics ◽  
Bacterial Classification ◽  
Surface Enhanced ◽  
Surface Enhanced Raman

AbstractUrinary tract infection is one of the most common bacterial infections leading to increased morbidity, mortality and societal costs. Current diagnostics exacerbate this problem due to an inability to provide timely pathogen identification. Surface enhanced Raman spectroscopy (SERS) has the potential to overcome these issues by providing immediate bacterial classification. To date, achieving accurate classification has required technically complicated processes to capture pathogens, which has precluded the integration of SERS into rapid diagnostics. This work demonstrates that gold-coated membrane filters capture and aggregate bacteria, separating them from urine, while also providing Raman signal enhancement. An optimal gold coating thickness of 50 nm was demonstrated, and the diagnostic performance of the SERS-active filters was assessed using phantom urine infection samples at clinically relevant concentrations (105 CFU/ml). Infected and uninfected (control) samples were identified with an accuracy of 91.1%. Amongst infected samples only, classification of three bacteria (Escherichia coli, Enterococcus faecalis, Klebsiella pneumoniae) was achieved at a rate of 91.6%.

scholarly journals Use of WetSEM® capsules for convenient multimodal scanning electron microscopy, energy dispersive X-ray analysis, and micro Raman spectroscopy characterisation of technetium oxides

2021 ◽  
Author(s):  
D. J. Bailey ◽  
M. C. Stennett ◽  
J. Heo ◽  
N. C. Hyatt
Keyword(s):  
Raman Spectroscopy ◽  
Low Cost ◽  
Powder Materials ◽  
Spectroscopy Analysis ◽  
X Ray ◽  
Micro Raman Spectroscopy ◽  
Hazard And Risk ◽  
Sem Imaging ◽  
General User ◽  
532 Nm

AbstractSEM–EDX and Raman spectroscopy analysis of radioactive compounds is often restricted to dedicated instrumentation, within radiological working areas, to manage the hazard and risk of contamination. Here, we demonstrate application of WetSEM® capsules for containment of technetium powder materials, enabling routine multimodal characterisation with general user instrumentation, outside of a controlled radiological working area. The electron transparent membrane of WetSEM® capsules enables SEM imaging of submicron non-conducting technetium powders and acquisition of Tc Lα X-ray emission, using a low cost desktop SEM–EDX system, as well as acquisition of good quality μ-Raman spectra using a 532 nm laser.

scholarly journals Fabrication-friendly polarization-sensitive plasmonic grating for optimal surface-enhanced Raman spectroscopy

2020 ◽  
Vol 16 (1) ◽  
Author(s):  
Arpan Dutta ◽  
Tarmo Nuutinen ◽  
Khairul Alam ◽  
Antti Matikainen ◽  
Peng Li ◽  
...  
Keyword(s):  
Raman Spectroscopy ◽  
Fill Factor ◽  
Surface Enhanced Raman Spectroscopy ◽  
Transverse Magnetic ◽  
Raman Signal ◽  
Optical Resonance ◽  
Excitation Light ◽  
Surface Enhanced ◽  
Surface Enhanced Raman ◽  
Plasmonic Gratings

Abstract Plasmonic nanostructures are widely utilized in surface-enhanced Raman spectroscopy (SERS) from ultraviolet to near-infrared applications. Periodic nanoplasmonic systems such as plasmonic gratings are of great interest as SERS-active substrates due to their strong polarization dependence and ease of fabrication. In this work, we modelled a silver grating that manifests a subradiant plasmonic resonance as a dip in its reflectivity with significant near-field enhancement only for transverse-magnetic (TM) polarization of light. We investigated the role of its fill factor, commonly defined as a ratio between the width of the grating groove and the grating period, on the SERS enhancement. We designed multiple gratings having different fill factors using finite-difference time-domain (FDTD) simulations to incorporate different degrees of spectral detunings in their reflection dips from our Raman excitation (488 nm). Our numerical studies suggested that by tuning the spectral position of the optical resonance of the grating, via modifying their fill factor, we could optimize the achievable SERS enhancement. Moreover, by changing the polarization of the excitation light from transverse-magnetic to transverse-electric, we can disable the optical resonance of the gratings resulting in negligible SERS performance. To verify this, we fabricated and optically characterized the modelled gratings and ensured the presence of the desired detunings in their optical responses. Our Raman analysis on riboflavin confirmed that the higher overlap between the grating resonance and the intended Raman excitation yields stronger Raman enhancement only for TM polarized light. Our findings provide insight on the development of fabrication-friendly plasmonic gratings for optimal intensification of the Raman signal with an extra degree of control through the polarization of the excitation light. This feature enables studying Raman signal of exactly the same molecules with and without electromagnetic SERS enhancements, just by changing the polarization of the excitation, and thereby permits detailed studies on the selection rules and the chemical enhancements possibly involved in SERS.

scholarly journals Laser Raman Spectroscopy with Different Excitation Sources and Extension to Surface Enhanced Raman Spectroscopy

2015 ◽  
Vol 2015 ◽  
pp. 1-8 ◽  
Author(s):  
Md. Wahadoszamen ◽  
Arifur Rahaman ◽  
Nabil Md. Rakinul Hoque ◽  
Aminul I Talukder ◽  
Kazi Monowar Abedin ◽  
...  
Keyword(s):  
Raman Spectroscopy ◽  
Silver Nanoparticles ◽  
Rhodamine 6G ◽  
Detection Efficiency ◽  
Colloidal Suspension ◽  
Surface Enhanced Raman Spectroscopy ◽  
Laser Raman Spectroscopy ◽  
Raman Signal ◽  
Fluorescence Signal ◽  
Present System

A dispersive Raman spectrometer was used with three different excitation sources (Argon-ion, He-Ne, and Diode lasers operating at 514.5 nm, 633 nm, and 782 nm, resp.). The system was employed to a variety of Raman active compounds. Many of the compounds exhibit very strong fluorescence while being excited with a laser emitting at UV-VIS region, hereby imposing severe limitation to the detection efficiency of the particular Raman system. The Raman system with variable excitation laser sources provided us with a desired flexibility toward the suppression of unwanted fluorescence signal. With this Raman system, we could detect and specify the different vibrational modes of various hazardous organic compounds and some typical dyes (both fluorescent and nonfluorescent). We then compared those results with the ones reported in literature and found the deviation within the range of ±2 cm−1, which indicates reasonable accuracy and usability of the Raman system. Then, the surface enhancement technique of Raman spectrum was employed to the present system. To this end, we used chemically prepared colloidal suspension of silver nanoparticles as substrate and Rhodamine 6G as probe. We could observe significant enhancement of Raman signal from Rhodamine 6G using the colloidal solution of silver nanoparticles the average magnitude of which is estimated to be 103.

Laser Induced Oxidation Effects in Bismuth Thin Films

2012 ◽  
Vol 1477 ◽  
Author(s):  
Marco A. Zepeda ◽  
Michel Picquart ◽  
Emmanuel Haro-Poniatowski
Keyword(s):  
Thin Films ◽  
Raman Spectroscopy ◽  
Laser Irradiation ◽  
Raman Spectra ◽  
Exposure Time ◽  
Oxidation Process ◽  
Energy Dispersion Spectroscopy ◽  
Irradiation Power ◽  
Pure Bismuth ◽  
532 Nm

ABSTRACTThe Laser induced oxidation process of bismuth was investigated using Raman spectroscopy. Upon laser irradiation (λ = 532 nm) pure Bismuth was transformed gradually into Bi2O3. Raman spectra of the samples showed the characteristics peaks for pure Bi located at 71 cm-1 and 96 cm-1. The oxidation process was monitored by Raman spectra with four additional bands located at about 127 cm-1, 241 cm-1, 313 cm-1 and 455 cm-1. Maintaining constant the exposure time of irradiation, the intensity of these bands depended on laser irradiation power. The presence of Bi2O3 in the sample was confirmed through by energy dispersion spectroscopy (EDS).

Raman Spectroscopy for the Study of XVI-XVII Centuries Colonial Paintings

2014 ◽  
Vol 1618 ◽  
pp. 141-151 ◽  
Author(s):  
Ma. A. García-Bucio ◽  
E. Casanova-González ◽  
J. L. Ruvalcaba-Sil
Keyword(s):  
Raman Spectroscopy ◽  
San Francisco ◽  
Reference Materials ◽  
Analytical Techniques ◽  
Surface Enhanced Raman Spectroscopy ◽  
Raman Signal ◽  
Invasive Approach ◽  
Full Characterization ◽  
Surface Enhanced Raman ◽  
Historical Objects

ABSTRACTOutstanding information about the material composition and pictorial techniques of the New Spain Colonial painting can be obtained via a full characterization using a set of analytical techniques. Given the cultural importance of this painting, a non-invasive approach is preferred. Moreover, the preparation and use of reference materials using original recipes is necessary for a correct interpretation of the spectroscopic data from historical objects. Here, we present the results obtained via an in-situ Raman spectroscopic analysis of a set of pictorial reference materials, created according to XVI and XVII centuries’ recipes. Several difficulties were encountered, such as the low Raman detection signal, an intrinsic fluorescence of the material, and in some cases even laser-induced degradation. For this reason, the usual molecular Raman analysis was extended to Surface Enhanced Raman Spectroscopy (SERS), which enhances the Raman signal and quenches the fluorescence. It was then applied to the analysis of two wood paintings from the ex-convent San Francisco Tepeyanco, in Tlaxcala.

scholarly journals Current and Future Advancements of Raman Spectroscopy Techniques in Cancer Nanomedicine

2021 ◽  
Vol 22 (23) ◽  
pp. 13141
Author(s):  
Elisabetta Canetta
Keyword(s):  
Raman Spectroscopy ◽  
Imaging Techniques ◽  
Rapid Development ◽  
Surface Enhanced Raman Spectroscopy ◽  
Cancer Diagnostics ◽  
Raman Signal ◽  
Therapeutic Effects ◽  
Cancer Nanomedicine

Raman scattering is one of the most used spectroscopy and imaging techniques in cancer nanomedicine due to its high spatial resolution, high chemical specificity, and multiplexity modalities. The flexibility of Raman techniques has led, in the past few years, to the rapid development of Raman spectroscopy and imaging for nanodiagnostics, nanotherapy, and nanotheranostics. This review focuses on the applications of spontaneous Raman spectroscopy and bioimaging to cancer nanotheranostics and their coupling to a variety of diagnostic/therapy methods to create nanoparticle-free theranostic systems for cancer diagnostics and therapy. Recent implementations of confocal Raman spectroscopy that led to the development of platforms for monitoring the therapeutic effects of anticancer drugs in vitro and in vivo are also reviewed. Another Raman technique that is largely employed in cancer nanomedicine, due to its ability to enhance the Raman signal, is surface-enhanced Raman spectroscopy (SERS). This review also explores the applications of the different types of SERS, such as SERRS and SORS, to cancer diagnosis through SERS nanoprobes and the detection of small-size biomarkers, such as exosomes. SERS cancer immunotherapy and immuno-SERS (iSERS) microscopy are reviewed.

scholarly journals Ring Vibrations to Sense Anionic Ibuprofen in Aqueous Solution as Revealed by Resonance Raman

Molecules ◽  
2022 ◽  
Vol 27 (2) ◽  
pp. 442
Author(s):  
Sara Gómez ◽  
Natalia Rojas-Valencia ◽  
Tommaso Giovannini ◽  
Albeiro Restrepo ◽  
Chiara Cappelli
Keyword(s):  
Molecular Dynamics ◽  
Aqueous Solution ◽  
Raman Spectroscopy ◽  
Natural Bond Orbital ◽  
Resonance Raman Spectroscopy ◽  
Resonance Raman ◽  
Nbo Analysis ◽  
Raman Signal ◽  
Incident Wavelength ◽  
Selective Enhancement

We unravel the potentialities of resonance Raman spectroscopy to detect ibuprofen in diluted aqueous solutions. In particular, we exploit a fully polarizable quantum mechanics/molecular mechanics (QM/MM) methodology based on fluctuating charges coupled to molecular dynamics (MD) in order to take into account the dynamical aspects of the solvation phenomenon. Our findings, which are discussed in light of a natural bond orbital (NBO) analysis, reveal that a selective enhancement of the Raman signal due to the normal mode associated with the C–C stretching in the ring, νC=C, can be achieved by properly tuning the incident wavelength, thus facilitating the recognition of ibuprofen in water samples.

Rhodium nanocubes and nanotripods for highly sensitive ultraviolet surface-enhanced Raman spectroscopy

The Analyst ◽  
2018 ◽  
Vol 143 (10) ◽  
pp. 2310-2322 ◽  
Author(s):  
Rupali Das ◽  
R. K. Soni
Keyword(s):  
Raman Spectroscopy ◽  
Surface Enhanced Raman Spectroscopy ◽  
Excitation Wavelength ◽  
Rhodium Nanoparticles ◽  
Highly Sensitive ◽  
Surface Enhanced ◽  
Surface Enhanced Raman ◽  
532 Nm

DUV-UV (266 nm), UV (325 nm) and visible (532 nm) excitation-wavelength-dependent SERS investigation of adenine molecules on rhodium nanoparticles.

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