Ghita Adrian, Hubbard Thomas, Matousek Pavel, Stone Nicholas
Biomedical Spectroscopy Lab, School of Physics and Astronomy, College of Engineering, Mathematics and Physical Sciences, University of Exeter, Stoker Road, Exeter EX4 4QL, U.K.
Institute of Biomedical and Clinical Science, University of Exeter Medical School, Exeter, EX1 2LU, U.K.
Anal Chem. 2020 Jul 21;92(14):9449-9453. doi: 10.1021/acs.analchem.0c01842. Epub 2020 Jul 7.
Here we conceptually demonstrate the capability of deep Raman spectroscopy to noninvasively monitor changes in the water content within biological tissues. Water was added by injection into an isolated tissue volume (a 20 mm diameter disk of 5 mm thickness) representing a 20% increase in the overall mass, which was equivalent to a 5% increase in the water/tissue content. The elevated water content was detected through a larger volume of tissue with a total thickness of approximately 12 mm and a spiked tissue segment located in its center using transmission Raman spectroscopy (TRS) by monitoring the change of the OH (∼3390 cm) Raman band area (3350-3550 cm spectral region) after being normalized to the neighboring CH stretching band. The tissue sample was raster scanned with TRS to yield a spatial map of the water concentration within the sample encompassing the spiked tissue zone. The mapping revealed the presence and location of the spiked region. The results provide the first conceptual demonstration using a deep Raman-based architecture, which can be used noninvasively for the detection of an elevated water content deep within biological tissues. It is envisaged that this concept could play a role in rapid in vivo detection and localization of cancerous lesions (generally exhibiting a higher water content) beneath the tissue surface.
