Raman spectroscopy of carbon nanotubes

The ability to control the size, shape, and material of a surface has reinvigorated the field of surface-enhanced Raman spectroscopy (SERS). Because excitation of the localized surface plasmon resonance of a nanostructured surface or nanoparticle lies at the heart of SERS, the ability to reliably control the surface characteristics has taken SERS from an interesting surface phenomenon to a rapidly developing analytical tool. This article first explains many fundamental features of SERS and then describes the use of nanosphere lithography for the fabrication of highly reproducible and robust SERS substrates. In particular, we review metal film over nanosphere surfaces as excellent candidates for several experiments that were once impossible with more primitive SERS substrates (e.g., metal island films). The article also describes progress in applying SERS to the detection of chemical warfare agents and several biological molecules.

Surface-Enhanced Raman Spectroscopy

https://uhra.herts.ac.uk/bitstream/handle/2299/1986/901994.pdf?sequence=1

Atmospheric polycyclic aromatic hydrocarbons: Source attribution, emission factors and regulation

Liming Dai,*,†,‡ Yuhua Xue,†,‡ Liangti Qu,* Hyun-Jung Choi, and Jong-Beom Baek* †Center of Advanced Science and Engineering for Carbon (Case4Carbon), Department of Macromolecular Science and Engineering, Case Western Reserve University, 10900 Euclid Avenue, Cleveland, Ohio 44106, United States Key Laboratory of Cluster Science, Ministry of Education of China, Beijing Key Laboratory of Photoelectronic/Electrophotonic Conversion Materials, Department of Chemistry, School of Science, Beijing Institute of Technology, Beijing 100081, People’s Republic of China School of Energy and Chemical Engineering/Center for Dimension-Controllable Covalent Organic Frameworks, Ulsan National Institute of Science and Technology (UNIST), 100 Banyeon, Ulsan, 689-798, South Korea

Metal-free catalysts for oxygen reduction reaction.

Carbon nanotubes exhibit many unique intrinsic physical and chemical properties and have been intensively explored for biological and biomedical applications in the past few years. In this comprehensive review, we summarize the main results from our and other groups in this field and clarify that surface functionalization is critical to the behavior of carbon nanotubes in biological systems. Ultrasensitive detection of biological species with carbon nanotubes can be realized after surface passivation to inhibit the non-specific binding of biomolecules on the hydrophobic nanotube surface. Electrical nanosensors based on nanotubes provide a label-free approach to biological detection. Surface-enhanced Raman spectroscopy of carbon nanotubes opens up a method of protein microarray with detection sensitivity down to 1 fmol/L. In vitro and in vivo toxicity studies reveal that highly water soluble and serum stable nanotubes are biocompatible, nontoxic, and potentially useful for biomedical applications. In vivo biodistributions vary with the functionalization and possibly also size of nanotubes, with a tendency to accumulate in the reticuloendothelial system (RES), including the liver and spleen, after intravenous administration. If well functionalized, nanotubes may be excreted mainly through the biliary pathway in feces. Carbon nanotube-based drug delivery has shown promise in various In vitro and in vivo experiments including delivery of small interfering RNA (siRNA), paclitaxel and doxorubicin. Moreover, single-walled carbon nanotubes with various interesting intrinsic optical properties have been used as novel photoluminescence, Raman, and photoacoustic contrast agents for imaging of cells and animals. Further multidisciplinary explorations in this field may bring new opportunities in the realm of biomedicine.

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Carbon Nanotubes in Biology and Medicine: In vitro and in vivo Detection, Imaging and Drug Delivery

We show that the Raman scattering technique can give complete structural information for one-dimensional systems, such as carbon nanotubes. Resonant confocal micro-Raman spectroscopy of an (n,m) individual single-wall nanotube makes it possible to assign its chirality uniquely by measuring one radial breathing mode frequency omega(RBM) and using the theory of resonant transitions. A unique chirality assignment can be made for both metallic and semiconducting nanotubes of diameter d(t), using the parameters gamma(0) = 2.9 eV and omega(RBM) = 248/d(t). For example, the strong RBM intensity observed at 156 cm(-1) for 785 nm laser excitation is assigned to the (13,10) metallic chiral nanotube on a Si/SiO2 surface.

Structural (n,m) determination of isolated single wall carbon nanotubes by resonant Raman scattering

We report the first successful study of the use of Raman spectroscopy for quantitative, noninvasive ("transcutaneous") measurement of blood analytes, using glucose as an example. As an initial evaluation of the ability of Raman spectroscopy to measure glucose transcutaneously, we studied 17 healthy human subjects whose blood glucose levels were elevated over a period of 2-3 h using a standard glucose tolerance test protocol. During the test, 461 Raman spectra were collected transcutaneously along with glucose reference values provided by standard capillary blood analysis. A partial least squares calibration was created from the data from each subject and validated using leave-one-out cross validation. The mean absolute errors for each subject were 7.8% +/- 61.8% (mean +/- std) with R-2 values of 0.83 +/- 0.10. We provide spectral evidence that the glucose spectrum is an important part of the calibrations by analysis of the calibration regression vectors. (c) 2005 Society of Photo-Optical Instrumentation Engineers.

/pdf/raman-spectroscopy-for-noninvasive-glucose-measurements-15u6o5l1h1.pdf

Raman spectroscopy for noninvasive glucose measurements.

In vitro experiments have demonstrated the ability of Raman spectroscopy to diagnose a wide variety of diseases. Recent in vivo investigations performed with optical fiber probes were promising but generally limited to easily accessible organs, often requiring relatively long collection times. We have implemented an optical design strategy to utilize system throughput fully by characterizing the Raman distribution from tissue. This scheme optimizes collection efficiency, minimizes noise, and has resulted in small-diameter, highly efficient Raman probes that are capable of collecting high-quality data in 1 s. Performance has been tested through simulations and experiments with tissue models and several in vitro tissue types, demonstrating that this new design can advance Raman spectroscopy as a clinically practical technique.

Optical fiber probe for biomedical Raman spectroscopy.

Using a flow-tube reactor coupled to a chemical ionization mass spectrometer, we investigated the heterogeneous loss of OH on Halocarbon wax, two types of organized organic monolayers, and several solid organic surfaces (paraffin wax, stearic acid-palmitic acid mixture, pyrene, and soot) that are representative of surfaces found in the troposphere. The heterogeneous reaction is very efficient: the reaction probability is greater than 0.1 for all the organic surfaces investigated, except for Halocarbon wax. These results indicate that OH-organic heterogeneous reactions will significantly modify the hygroscopic properties and cloud condensation nuclei (CCN) ability of organic surfaces in the troposphere, and thus may play an important role in the Earth’s radiative balance by affecting the properties of clouds. We also determined the diffusion coefficient of OH in helium to be 665 ( 35 Torr cm 2 s -1 . This value is close to that of its polar analogue, H 2O, suggesting that the diffusion coefficient of OH can be calculated accurately with H2O transport properties.

The Reaction Probability of OH on Organic Surfaces of Tropospheric Interest

The system and method of the present invention relates to using spectroscopy, for example, Raman spectroscopic methods for diagnosis of tissue conditions such as vascular disease or cancer. In accordance with a preferred embodiment of the present invention, a system for measuring tissue includes a fiber optic probe having a proximal end, a distal end, and a diameter of 2 mm or less. This small diameter allows the system to be used for the diagnosis of coronary artery disease or other small lumens or soft tissue with minimal trauma. A delivery optical fiber is included in the probe coupled at the proximal end to a light source. A filter for the delivery fibers is included at the distal end. The system includes a collection optical fiber (or fibers) in the probe that collects Raman scattered radiation from tissue, the collection optical fiber is coupled at the proximal end to a detector. A second filter is disposed at the distal end of the collection fibers. An optical lens system is disposed at the distal end of the probe including a delivery waveguide coupled to the delivery fiber, a collection waveguide coupled to the collection fiber and a lens.

Martin Hunter

Papers

Structural (n,m) determination of isolated single wall carbon nanotubes by resonant Raman scattering

Raman spectroscopy for noninvasive glucose measurements.

Optical fiber probe for biomedical Raman spectroscopy.

The Reaction Probability of OH on Organic Surfaces of Tropospheric Interest

Systems and methods for spectroscopy of biological tissue