Biomedical Spectroscopy and Imaging - Volume 3, issue 3
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Biomedical Spectroscopy and Imaging (BSI) is a multidisciplinary journal devoted to the timely publication of basic and applied research that uses spectroscopic and imaging techniques in different areas of life science including biology, biochemistry, biotechnology, bionanotechnology, environmental science, food science, pharmaceutical science, physiology and medicine. Scientists are encouraged to submit their work for publication in the form of original articles, brief communications, rapid communications, reviews and mini-reviews.
The journal is dedicated to providing a single forum for experts in spectroscopy and imaging as applied to biomedical problems, and also for life scientists who use these powerful methods for advancing their research work. BSI aims to promote communication, understanding and synergy across the diverse disciplines that rely on spectroscopy and imaging. It also encourages the submission of articles describing development of new devices and technologies, based on spectroscopy and imaging methods, for application in diverse areas including medicine, biomedical science, biomaterials science, environmental science, pharmaceutical science, proteomics, genomics, metabolomics, microbiology, biotechnology, genetic engineering, nanotechnology, etc.
Abstract: Amylin is a small polypeptide that is implicated in type 2 diabetes. This article reviews the data and conclusions presented at the 2013 ECSBM meeting in Oxford about the aggregation mechanism of amylin into toxic oligomers and fibers. The process was studied using a pulse shaping method for collecting two-dimensional infrared (2D IR) spectra in order to monitor aggregation in real time. Isotope labeling was used to measure the secondary structure content of individual residues. It was found that prior to fiber formation, peptides aggregate into an intermediate that has parallel β-structure from residues 23–27, called the “FGAIL” region due…to its sequence. This region has long been implicated in the aggregation process, but with confusing and often contradictory experimental results. Our work using 2D IR spectroscopy has helped reconcile these perceived contradictions and provides a mechanism that helps explain sequence homology between species, drug inhibition, and aggregation kinetics.
Keywords: Amylin, infrared spectroscopy, 2D IR, aggregation pathway, intermediate
Abstract: Raman spectroscopy has shown considerable promise as a medical diagnostic tool. The technique is safe for use in vivo and is capable of rapid, objective assessment of neoplastic and inflammatory tissue enabling early diagnosis and targeted treatment. We review potential applications of Raman spectroscopy in the oesophagus, colon and breast where this new technology has the potential to revolutionise patient care.
Abstract: Cryopreservation of bacteria requires specific cells pre-adaptation as well as controlled freezing protocol to minimize membrane damage resulting from osmotic cell dehydration. Membrane fluidity has an important role in biophysical events taking place at subzero temperatures, by facilitating or not the exchanges between intracellular and extracellular media. An original approach using Synchrotron fluorescence polarization microscopy was developed to measure membrane fluidity of single bacteria. Cells were labelled with the cytoplasmic membrane probe trimethylammoniumdiphenylhexatriene (TMA-DPH). The degrees of liberty of TMA-DPH inside the bilayer provide a direct marker of membrane fluidity under deep UV excitation. Couples of fluorescence polarization images from…zero to forty degrees were recorded by inserting polarizers into the excitation and emission paths. The fluorescence anisotropy of the images was calculated thus allowing the assessment of the cell membrane fluidity. Results indicate intercellular and intracellular heterogeneities with subdomains appearing at low temperature for freeze-sensitive cells.
Keywords: Anisotropy, lactic acid bacteria, membrane, fluidity, temperature effect, DUV
Abstract: Fluorescence lifetime imaging has been used to observe the real-time uptake in live mammalian cells of a combretastatin-type drug analogue that is a substituted stilbene with a cyano group at the bridging olefinic bond. Fluorescence spectra in a range of solvents show that this molecule has a substantial increase in dipole moment on promotion to the first excited singlet state that is indicative of intramolecular charge transfer (CT) from the methoxy substituents on the aromatic rings to the electron-withdrawing cyano group. This CT process is also demonstrated in picosecond time-resolved infrared measurements. Consistent with these observations, the molecule has been…found to have a large two-photon absorption cross-section, and suggests potential routes to the design of a molecule that could be effectively activated by photoisomerisation in a two-photon process.
Abstract: Terahertz time-domain, FTIR and Raman spectroscopic techniques are used to study the interaction of chymotrypsin (CT) with 18-crown-6 (CE). The THz and FTIR spectra of CT demonstrate only three weak spectral lines whereas the spectra of the CT–CE mixtures exhibit several developed spectral features. Raman spectroscopy proves the presence of the bands in the low-frequency range. The results indicate that an increase in the functional activity of CT in nonaqueous solvents can be related to the interaction of the protonated amino groups of the protein with the CE molecules. FTIR and Raman spectra of lyophilized native and denatured protein are…compared in the fingerprint and low-frequency ranges. Possible structural differences related to the spectral changes are discussed.
Abstract: Raman spectroscopy is a powerful analytical tool however it suffers from poor sensitivity. Surface Enhanced Raman Spectroscopy (SERS) takes advantage of localised surface plasmons (LSPs) generated by metal nanostructures to significantly improve the sensitivity of Raman spectroscopy [J. Raman Spec. 43 (2012), 380–388], though this often results in poor reproducibility. Using silver colloids synthesised by the method outlined by Leopold and Lendl [Journal of Physical Chemistry B 107 (2003), 5723–5727], we have sought to improve both the sensitivity and reproducibility of the SERS spectra produced by this popular nanoparticle synthesis method.
Abstract: The enhanced green fluorescent protein (EGFP) is broadly used as an intracellular fluorescent marker. Its numerous applications require a comprehensive understanding of EGFP folding properties, as well as the properties of EGFP-derived mutants. Herein, we report on the spectroscopic characterization of two single-cysteine mutants, C48S-EGFP and C70S-EGFP, which were prepared to monitor the protein folding dynamics by EPR, specifically in the close vicinity of both cysteine residues. Chromophore absorption, excitation and emission spectra for these mutants were similar to those for EGFP. Both single-cysteine mutants were more susceptible to aggregation than EGFP in E. coli. C48S-EGFP exhibited similar…resistance to chemical denaturation as EGFP. In contrast, C70S-EGFP was less resistant to denaturation in guanidine hydrochloride and its folding was less efficient. Hence, C48S-EGFP seems to be a more suitable probe for EPR measurements than C70S-EGFP.
Keywords: Enhanced green fluorescent protein (EGFP), C48S-EGFP, C70S-EGFP, spectroscopic properties, fluorescence, absorption
Abstract: BACKGROUND: Biomechanical and biochemical properties are altered between healthy, cancerous, and metastatic cancer cells. These changes include altered lipid metabolism, resulting in varied lipid contents; varied nuclear organisation and size, which affect proliferation and transcription; and lower adhesion and rigidity, which enhance their capacities to escape primary tumour site, invade local stroma and metastasise. OBJECTIVE: In the literature, the mechanical and the chemical properties have been obtained from cells separately. We wish to demonstrate the techniques can be combined and applied to the same cells. This will allow for the correlation between chemical and mechanical properties to be studied,…and therefore the gaining of knowledge on how the underlying chemistry affects the cell's mechanical properties. Such information has implications on a better understanding of tumour progression. METHODS: 3D confocal Raman and atomic force microscopy (AFM) imaging – which are correlative and complementary – were applied to the same U-87MG glioma cells to describe their organelles' chemistry and volumes and the cells' rigidity via Young's modulus (YM) calculation. RESULTS: Chemical information and the YM were successfully obtained from the same cell using the described combined techniques. Using principal component analysis (PCA), the cells were found to differ in their lipid composition (in particular, cholesterol ester) even though they were from the same culture. This strongly implies the need of single cell analysis. CONCLUSION: The combined techniques allowed for the extraction of biomechanical and biochemical information from the same cancer cells. This will enable the investigation of their correlation on the single cell level. The combined techniques can provide powerful insights that will lead to improvements in brain cancer treatments, preventative measures and provide targets for the effectiveness of treatment.
Keywords: Raman, AFM, metastases, 3D imaging, cancer, brain
Abstract: Elastic fibers are responsible for elasticity of organs and tissues in vertebrates. Elastin is the amorphous component of these complex biopolymers and is an insoluble, highly cross-linked, hydrophobic protein assembled from a soluble precursor called tropoelastin. In order to elucidate the detailed structure of human tropoelastin, the exon-by-exon chemical synthesis of all the polypeptide sequences of the protein was accomplished. Herein, we review some of the most relevant results obtained at molecular, by using CD and NMR spectroscopies, and supramolecular level mainly by TEM. The overall results obtained for each polypeptide let us to assembly the elastin puzzle and envisaging…the whole structure of human tropoelastin. Analogous structural studies were carried out on some polypeptide sequences inspired to elastomeric proteins. These findings give useful insights into the elasticity mechanism of all elastomeric proteins. The knowledge can be exploited in the near future to design novel bioelastomers with tailored material properties for use in medicine and industry.
Keywords: Elastin, amyloid-like, polyproline II, transmission electron microscopy, circular dichroism, nuclear magnetic resonance