Chemical biology news from across RSC Publishing.
Instant insight: Revealing the hidden depths
20 July 2007
Pavel Matousek, at the Rutherford Appleton Laboratory, UK, describes emerging spectroscopic techniques that promise to change cancer and bone disease diagnosis.
Over the past two years we have witnessed the emergence of chemically specific analytical tools that could revolutionise the way various diseases are diagnosed. The same tools could also have a profound impact on how pharmaceutical product quality is assessed and hidden drugs and explosives are detected. The methods are based on Raman spectroscopy - a powerful vibrational spectroscopy technique.
Scientists use SORS to probe deep inside samples
The concept is based on collecting Raman spectra from regions away from the illumination point on the sample surface. Each laterally-offset Raman spectrum contains different relative contributions from sample layers at different depths. This difference is brought about by a wider lateral diffusion of photons emerging from greater depths - these photons have to travel larger distances and on their way they diffuse sideways to a greater extent than the photons originating from shallower layers. For a two-layer system, a simple scaled subtraction of two spectra obtained at different spatial offsets can be used to produce pure Raman spectra of individual layers. If there are more than two layers, as is often the case with biological samples, then multivariate data analysis of a more extensive data set is needed.
Spectra are collected away from the point of illumination
Examples of other applications include the quality control of pharmaceutical products, the non-invasive probing of counterfeit drugs through white plastic bottles and blister packs and the detection of powder explosives inside envelopes or plastic containers.
These exciting developments come at a time when Raman spectroscopy is completing its transformation from laboratory technique to practical analytical tool; a journey driven by recent advances in laser and detection technologies. Further developments of many of these new applications promise to exert a profound influence over our daily lives in the not too distant future.
Read Pavel Matousek's review 'Deep non-invasive Raman spectroscopy of living tissue and powders' in the August issue of Chemical Society Reviews.
Link to journal article
Deep non-invasive Raman spectroscopy of living tissue and powders
Pavel Matousek, Chem. Soc. Rev., 2007, 36, 1292