Merging optical with other imaging approaches
Yi-Hwa Liu, Albert J. Sinusas in Hybrid Imaging in Cardiovascular Medicine, 2017
Raman spectroscopy, an alternative method for detecting the molecular signatures of biological tissues, has also been investigated as a potential intravascular imaging modality. Rather than molecular absorption spectra, as is the basis for NIRS assessment, Raman spectroscopy relies on frequency shifts of emitted light, which are generated by an energy exchange between photons and molecular components of tissues. The magnitude of this energy exchange, and thus the extent of the frequency shift of received photons, is a function of a given molecule’s vibrational and rotational energies. Raman spectroscopy therefore offers the potential for very high molecular specificity. Whereas NIRS is used to differentiate lipid-rich plaques, Raman spectroscopy offers the potential to differentiate specific chemical components such as triglycerides, cholesterol, cholesterol esters, elastin, and collagen (Baraga, Feld, and Rava 1992; Manoharan et al. 1992; Brennan et al. 1997; Romer et al. 1998; van de Poll et al. 2003). Several intravascular Raman catheter prototypes have been developed and applied for arterial assessment including in the presence of luminal blood (Buschman et al. 2000; van de Poll et al. 2003; Motz et al. 2006; Chau et al. 2008). Additionally, it has been shown that Raman spectroscopy enables evaluation of pharmaceutical treatment efficacy through the quantification of plaque composition (van de Poll et al. 2001) as well as detection of vulnerable plaques with a sensitivity and specificity of 79% and 85%, respectively (Motz et al. 2006).
Drug Substance and Excipient Characterization
Dilip M. Parikh in Handbook of Pharmaceutical Granulation Technology, 2021
Raman spectroscopy and IR spectroscopy complement each other. The former measures a change in polarization, whereas the latter measures a change in dipole moment. IR-inactive vibrations can be strong in Raman spectra and vice versa. For example, vibrations in the wavenumber region of l0–400 cm‒1 are more easily studied by Raman than by IR spectroscopy. One advantage of the Raman spectroscopy method is that no sample preparation is required, thus the likelihood of inducing phase changes through sample preparation is avoided. However, representative sampling is critical for quantitative analysis. The results are affected by the particle size of the material. The use of Fourier transform Raman spectrometers with a longer wavelength laser of 1064 nm eliminates the problem of any fluorescent background. With the utilization of fiber optics, real-time crystallization can be monitored. Thus, this method is useful for in-line monitoring of pharmaceutical processes.
Understanding the Role of Existing Technology in the Fight Against COVID-19
Ram Shringar Raw, Vishal Jain, Sanjoy Das, Meenakshi Sharma in Pandemic Detection and Analysis Through Smart Computing Technologies, 2022
Raman spectroscopy is another highly sensitive and useful vibrational spectroscopy technique that allows non-destructive and real-time analysis of biological samples. A Raman spectrum is obtained by the process of scattering of light, whereas in FTIR, it is obtained by absorption of light by the matter. When a monochromatic (laser source) light is incident on the sample, the light may interact with the material either elastically or inelastically. In the elastic scattering, the incident photon is absorbed and reemitted with the same energy (frequency). This is known as Rayleigh scattering. On the other hand, in an inelastic scattering, the absorbed photon may be emitted with frequency higher or lower than the incident photon. The probability of inelastic scattering is very small compared to the Rayleigh scattering. The process of light scattering is shown in Figure 2.4. When the frequency of emitted photon (ν2) is less than the incident frequency (ν1), it is known as Stokes Raman scattering. When the frequency of emitted photon (ν2) is more than the incident frequency (ν1), it is known as anti-Stokes Raman scattering. This phenomenon is known as the Raman effect, and the observed effect is specific to the molecules causing the scattering. Thus, the Raman signals are used for determining the presence of molecules and their states using the inelastic scattering.
Multi-attribute Raman spectroscopy (MARS) for monitoring product quality attributes in formulated monoclonal antibody therapeutics
Published in mAbs, 2022
Bingchuan Wei, Nicholas Woon, Lu Dai, Raphael Fish, Michelle Tai, Winode Handagama, Ashley Yin, Jia Sun, Andrew Maier, Dana McDaniel, Elvira Kadaub, Jessica Yang, Miguel Saggu, Ann Woys, Oxana Pester, Danny Lambert, Alex Pell, Zhiqi Hao, Gordon Magill, Jack Yim, Jefferson Chan, Lindsay Yang, Frank Macchi, Christian Bell, Galahad Deperalta, Yan Chen
Raman spectroscopy has the potential to be a valuable multi-attribute method for characterizing biotherapeutics.6 Raman spectroscopy is a nondestructive vibrational spectroscopic method that requires little to no sample preparation and is suitable for measuring aqueous samples. Raman spectroscopy measures the energy of the inelastic scattering of photons by analytes. The wavelength shifts from the excitation wavelength of a monochromatic light source correlate to the vibrational energies of chemical bonds. A molecule can have multiple vibrational modes, each causing characteristic scattering and resulting in multiple Raman peaks that provide rich spectral information. Raman spectroscopy can simultaneously quantify the components of mixtures and provide insight into sample composition, structure, and conformation of analytes.7,8 The relationship between all the components with Raman responses and each wavenumber measurement in the Raman spectra can be modeled by multivariate data analysis (MVDA), which enables the predictions of multiple analytes or attributes in a complex mixture through the acquisition of a single spectrum.9–11
Role of necroptosis of alveolar macrophages in acute lung inflammation of mice exposed to titanium dioxide nanoparticles
Published in Nanotoxicology, 2021
Tomoya Sagawa, Akiko Honda, Raga Ishikawa, Natsuko Miyasaka, Megumi Nagao, Sakiko Akaji, Takashi Kida, Takahiro Tsujikawa, Tatsushi Yoshida, Yutaka Kawahito, Hirohisa Takano
Although it has been reported that TiO2 nanoparticles are phagocytosed by macrophages in the lung, and electron microscopy is the standard method for determining the localization of TiO2 nanoparticles in cells (Xu et al. 2010; Numano et al. 2014; Abdulnasser Harfoush et al. 2020), electron microscopy requires pretreatment to observe biological samples and is difficult to combine with other assays. Raman spectroscopy is a low-invasive technique that allows for chemical analysis by optical means without reagents, staining, or sample preparation, and enables nondestructive, label-free measurement of the chemical composition of complex biological samples such as body fluids, cells, and tissues (Bourbousson et al. 2019). Raman spectroscopy has been used to examine the localization of TiO2 nanoparticles in lung cells (Nakajima et al. 2011; Li et al. 2013) but has not been combined with other assays for the same sample. In this study, the combination of Raman spectroscopic imaging with HE staining, immunostaining, and Diff-Quick staining clearly showed that AMs phagocytosed TiO2 nanoparticles. Applying multiplex immunohistochemical analysis (Tsujikawa et al. 2017), which can be used in combination with immunostaining of more markers, may reveal the relationship between the intra/extracellular localization of particles and a variety of biological responses temporally and spatially. This technique can also be applied in various fields for pathology and histology analyses.
Fourier-transform Infrared (FT-IR) spectroscopy fingerprints subpopulations of extracellular vesicles of different sizes and cellular origin
Published in Journal of Extracellular Vesicles, 2020
Lucia Paolini, Stefania Federici, Giovanni Consoli, Diletta Arceri, Annalisa Radeghieri, Ivano Alessandri, Paolo Bergese
Complementary spectroscopic approaches, such as Raman spectroscopy, have already been reported to distinguish EVs [12–14]. However, Raman Spectroscopy suffers from very low sensitivity. This drawback is often circumvented by coupling the analytes with plasmonic nanoparticles (SERS) [15,16], by labelling them with organic dyes (Raman reporters), or immune-labelling with nanoprobes [17]. These strategies allowed to distinguish EVs from various sources, disease contexts [18,19] and single-vesicle analysis [20–22]. SERS-active nanostructures can enhance the Raman signals of target molecules by several orders of magnitude, but can have problems in stability, poor reproducibility, and sample damaging according to their material composition and architecture [23,24]. Those approaches might introduce pitfalls in data analysis, which might strongly affect the classification of EV subpopulations. Moreover, commercially available instrumentation for Raman spectroscopy is typically more complex and expensive than the corresponding FT-IR spectrometers. For these reasons, we decided to focus our study on FT-IR.
Related Knowledge Centers
- Molecule
- Rayleigh Scattering
- Inelastic Scattering
- Laser
- Scattering
- Resonant Inelastic X-Ray Scattering
- Pulsed Laser
- Mie Scattering
- Photographic Plate
- X-Ray Raman Scattering