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Exotic Imaging Approaches
Published in George C. Kagadis, Nancy L. Ford, Dimitrios N. Karnabatidis, George K. Loudos, Handbook of Small Animal Imaging, 2018
Maria Koutsoupidou, Irene S. Karanasiou
As mentioned earlier, THz is sensitive to interactions between molecules and to small changes in molecular structure and concentrations of proteins. Recent advances in THz technology improved the sensitivity of THz spectroscopy leading the way toward THz chemical imaging. It allows molecular recognition based on the spectroscopy of molecular networks providing in parallel dynamic functional information. THz chemical imaging can reveal hydrogen bond distributions and has been used in a variety of applications in this area showing significant potential (Ajito and Ueno 2011; Sun et al. 2011b). Several studies have been reported using THz spectroscopy for identifying intermolecular hydrogen bonds in biological samples, such as organic acids (Ueno and Ajito 2007), amino acids (Korter et al. 2006; Rungsawang et al. 2006a), sugars (Rungsawang et al. 2006b), pharmaceuticals (Ajito et al. 2011), polypeptides (Yamamoto et al. 2005; Plusquellic et al. 2007), DNA (Markelz et al. 2000; Luo et al. 2006), proteins (Ebbinghaus et al. 2008), and cancer cells (Ashworth et al. 2009; Oh et al. 2009). Amino acids and pharmaceuticals have hydrogen bonds, which have specific fingerprints in THz spectra that enable also quantitative analyses (Ueno et al. 2006; Nguyen et al. 2007; Ajito and Ueno 2011; Sun et al. 2011b).
Medication: Nanoparticles for Imaging and Drug Delivery
Published in Harry F. Tibbals, Medical Nanotechnology and Nanomedicine, 2017
Nanoparticles are used as contrast enhancement and image intensification agents for x-ray imaging and CT. Conventional x-ray and tomography imaging agents are molecular iodine compounds such as iodinated benzoic acid derivatives. In addition to having risk factors associated with intravenous iodine injection, such low molecular weight chemical imaging agents clear from the human body relatively rapidly, making it difficult to target disease sites.
Overview of Second- and Third-Order Nonlinear Optical Processes for Deep Imaging
Published in Lingyan Shi, Robert R. Alfano, Deep Imaging in Tissue and Biomedical Materials, 2017
Murugkar Sangeeta, Robert W. Boyd
Two-photon-excited fluorescence (TPEF) or two-photon microscopy has been extensively applied for biological imaging over the past couple of decades [2, 3]. In TPEF, a single femtosecond pulsed laser beam is tightly focused in the specimen such that two low energy, near-IR photons are simultaneously absorbed by a fluorophore and then emitted as one photon at a higher frequency than the incident light. Along with TPEF, nonlinear optical imaging techniques such as second harmonic generation (SHG) and coherent Raman scattering (CRS) have experienced continued growth in the technology and applications over the past decade. In SHG, two photons with the same frequency interacting with a nonlinear optical material are effectively “combined” to generate new photons at twice the frequency of the incident light [4]. CRS, which refers to both stimulated Raman scattering (SRS) and coherent anti-Stokes Raman scattering (CARS), is a technique to enhance spontaneous Raman scattering. The spontaneous Raman effect involves incoherent excitation of molecular vibrations. It is inherently weak in nature with the typical photon conversion efficiencies for Raman being lower than 1 in 1018. This results in long data acquisition times of 100 ms to 1 s per pixel and does not permit fast chemical imaging of a living system [5]. In contrast, CRS involves nonlinear Raman scattering such that molecular vibrations are driven coherently, in phase through stimulated excitation by two synchronized femtosecond (or picosecond) pulsed lasers. This translates to a reduction of the image acquisition time from many minutes or hours required in confocal Raman microscopy to only a couple of seconds using coherent Raman scattering microscopy [6, 7]. CARS and SRS have been shown to be promising techniques for the chemically selective imaging of lipids, proteins, and DNA in skin, brain, and lung tissue. TPEF and SHG enable selective imaging of auto-fluorescent proteins in tissue and of noncentrosymmetric structures such as fibrillar collagen, respectively [8]. We note that in many of these studies the illumination method of choice is one based on the nonlinear optical process of supercontinuum generation (SCG).
Pyrimethamine 3D printlets for pediatric toxoplasmosis: design, pharmacokinetics, and anti-toxoplasma activity
Published in Expert Opinion on Drug Delivery, 2023
Ziyaur Rahman, Tahir Khuroo, Eman M Mohamed, Sathish Dharani, Canberk Kayalar, Mathew A. Kuttolamadom, Lamba Omar Sangaré, Mansoor A. Khan
Near-infrared chemical imaging technique (NIR-CI) can visualize spatial distribution of the components in a matrix. NIR-CI is based on NIR principle and also called hyperspectroscopy. Each pixel represents a spectrum of chemical entity or mixture of entity. Distribution of individual component is determined by use of mathematical method called principle component analysis (PCA) or partial least squared. PCA is primarily used for qualitative analysis [35]. PCA concentration images of the printlets were obtained using PMT as a component from the library. Red, yellow-green, and blue pixels mean high, medium, and low concentration of the PMT in that space of the mixture, respectively. The concentration images showed relatively uniform distribution of pixel color that indicated uniform distribution of the drug. Furthermore, pixel color distribution also uniforms in top and bottom surface of the printlets that indicated no effect of the process on the drug distribution (Figure 2C).
Application of salt engineering to reduce/mask bitter taste of clindamycin
Published in Drug Development and Industrial Pharmacy, 2019
Sogra F. Barakh Ali, Sathish Dharani, Hamideh Afrooz, Mansoor A. Khan, Eman M. Mohamed, Kanchan Kohli, Ziyaur Rahman
NIR hyperspectral chemical imaging provides chemical and spatial information of components in a matrix. Principle component analysis (PCA) and partial least squares are commonly used method for qualitative and quantitative analysis of components [30,34]. PCA provides qualitative information and grouping of similar/identical samples. The PCA images of CLN-HCl, CYA, and CLN-CYA are shown in Figure 6. Pixels color of CLN-HCl and CYA components were uniform, and light blue and red, respectively, which indicated method was quite capable of distinguishing the components. Furthermore, pixels color of physical mixture of CYA and CLN-HCl was not uniform and appeared as two colored pixels namely sky blue and yellow. On the other hand, CLN-CYA salt PCA image appeared as uniform pixels of dark blue color. If it were a physical mixture, it would appear as two different colored pixels representing two components. This indicated formation of new compound and it was not a physical mixture.
Near-infrared spectroscopic applications in pharmaceutical particle technology
Published in Drug Development and Industrial Pharmacy, 2019
M. Razuc, A. Grafia, L. Gallo, M. V. Ramírez-Rigo, R. J. Romañach
The main advances in NIRS providing valuable information on powder and solid dosage forms were summarized demonstrating the significant progress of this analytical technique. NIRS is now widely implemented in industrial processes, including batch and continuous processes, and real-time release testing strategies. Regulatory guidances are now available for the submission and evaluation of new NIR methods. Methods have been developed to provide physical and chemical characterization of raw materials, intermediate, and final products. This article shows the wide applicability of NIRS to multiple formulations and drug products, including suspensions, 3d printed tablets, conventional and modified release drug delivery systems. There are also advances in NIR spectrometers, chemical imaging, and portable instruments are now common. NIRS is part of many PAT strategies, and in-line methods are now providing valuable information to control systems.