https://www.chemistryworld.com/features/ready-for-a-raman-shift/3009970.article The Raman effect occurs because of molecular vibrations in the material that take energy from, or give it to, photons of light, causing a change in wavelength or colour. Importantly, the nature of that change is unique to the molecules inhabiting the material; it can be thought of as a chemical fingerprint. Because Raman spectroscopy can pick out very small chemical changes, it allows biomedical researchers to spot even minor fluctuations in the molecules associated with disease and categorise tissues according to whether they are healthy or not. This is achieved in spite of the fact that Raman is ‘fundamentally a weak technique’, explains Karen Faulds, a Raman expert at the University of Strathclyde in Scotland. Raman scattering was barely detectable back in the 1920s because such a small portion of the incoming light behaves in this way; only one in a million or even 10 million photons. Raman and Krishnan had to focus sunlight through a 180mm telescope to get a strong enough beam for their experiments. According to Faulds, we’re only able to get better signals today due to a raft of technological advancements: ‘The instrumentation, the detectors, the lasers, the filters and so on.’ ... According to Faulds, Raman researchers are now starting to find ways for their techniques to fit into clinical pathways. So what diseases can you detect using a Raman spectrometer? More than you’d think – the diagnostic power of Raman seems to know no bounds, in fact. A group led by Luis González-Solís at Centro Universitario de los Lagos in Mexico, for example, tested Raman for diagnosing tooth decay, type 2 diabetes, and breast and cervical cancer, and for monitoring leukaemia treatments, just in the last four years. Another group at the Massachusetts Institute of Technology (MIT) in the US is developing Raman-based technology for guiding placement of epidural needles and continuous blood glucose monitoring for diabetics. |
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