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SPECTROSCOPY 41


I


n recent months, several universities and research organisations have made


important breakthroughs in the use of Raman spectroscopy (RS) methods for health applications. So, what did the research entail? And how exactly was RS technology applied in each case?


Mapping human cartilage One of the most interesting recent initiatives is an Imperial College London project that is using RS to accurately map human cartilage and compare it to engineered cartilage at various stages while it is being grown in the laboratory. As Mads Sylvest Bergholt, Research Fellow at Imperial College London, explains, RS is a vital tool in the work because it essentially provides a chemical ‘fingerprint’ of the composition of a sample, as well as some information on the organisation of specific components such as collagen fibre orientation, in the form of a spectrum. “We can scan a tissue and obtain these spectra for every location in the tissue. In this work, we have imaged bovine cartilage and extracted information about collagen, glycosaminoglycan and water content in the tissues – the three main components of cartilage,” he says. “We found that cartilage was


more complex than previously thought, with at least six groups, zones or layers that differ not just by the content of their main components and the orientation of collagen, but also by the presence of other chemical species in the sample. Tis is in sharp contrast to the currently accepted three zone or layer model in the literature,” he adds. As part of the work, which


forms part of the ongoing UK Regenerative Medicine Platform that seeks to apply RS to tissue engineering in an effort


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to study how well scientists can reproduce native tissue, the team further demonstrated that it could grow tissue- engineered cartilage in the lab and then use RS to quantitatively characterise its biochemical composition and compare it with native tissue. In Bergholt’s view, one of the main advantages of RS over conventional imaging approaches is the fact that it does not need labelling and therefore requires little or no sample preparation. “It is also non-destructive and can therefore be used to study live-cells. One can do quantitative analysis since the Raman signal intensity is proportional to the sample concentration,” he says. In addition to using RS as a lab-based tool for cell and tissue characterisation, the Imperial team has also developed a computational approach to analysing cells volumetrically using Raman microspectroscopy – specifically an alpha300R+ confocal Raman micro-spectroscope produced by WITec. According to Molly Stevens, professor of Biomedical Materials and Regenerative Medicine at ICL, most Raman studies in the literature of


cells have been performed by generating conventional 2D images of the biochemical distributions, which ‘does not enable accurate quantification since molecules become blurred throughout the depth of the cell.’


“In this work we developed analytical and computational methods, called quantitative volumetric Raman imaging (qVRI), that allow us to visualise molecules inside cells in 3D using high-resolution Raman microscopy,” she says. “We have integrated qVRI as


an important part of our lab and can apply this to study cells and tissue in biomedicine ranging from stem cell research, cancer biology to drug discovery. In the future, this will allow us to better characterise cell systems at the molecular level. Further, we are planning to correlate the qVRI results that we find with various other complementary techniques used in cell biology,” she adds.


‘Listening’ for cancer Elsewhere, a University of Strathclyde-led project has employed a combination of cutting-edge RS technology and audio signalling software to enable brain surgeons to


Matthew Baker from the University of Strathclyde


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