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,
,1
Queens University Belfast, Schools of
* Chemistry and Chemical Engineering,
Medicine and Dentistry,
School of Biomedical Science, Belfast, UK;
University of California at Davis, Davis, California, USA;
|| Departments of Ob/Gyn and Biochemistry, University of Western Ontario, London, Ontario, Canada
1Correspondence: Queens University Belfast, Respiratory Research Group, Department of Medicine, Grosvenor Rd., Belfast, BT12 6BJ UK. E-mail: b.schock{at}qub.ac.uk
Alpha-tocopherol (aT), the predominant form of vitamin E in mammals, is thought to prevent oxidation of polyunsaturated fatty acids. In the lung, aT is perceived to be accumulated in alveolar type II cells and secreted together with surfactant into the epithelial lining fluid. Conventionally, determination of aT and related compounds requires extraction with organic solvents. This study describes a new method to determine and image the distribution of aT and related compounds within cells and tissue sections using the light-scattering technique of Raman microscopy to enable high spatial as well as spectral resolution. This study compared the nondestructive analysis by Raman microscopy of vitamin E, in particular aT, in biological samples with data obtained using conventional HPLC analysis. Raman spectra were acquired at spatial resolutions of 20.8 µm. Multivariate analysis techniques were used for analyses and construction of corresponding maps showing the distribution of aT, alpha-tocopherol quinone (aTQ), and other constituents (hemes, proteins, DNA, and surfactant lipids). A combination of images enabled identification of colocalized constituents (heme/aTQ and aT/surfactant lipids). Our data demonstrate the ability of Raman microscopy to discriminate between different tocopherols and oxidation products in biological specimens without sample destruction. By enabling the visualization of lipid-protein interactions, Raman microscopy offers a novel method of investigating biological characterization of lipid-soluble compounds, including those that may be embedded in biological membranes such as aT. Beattie J. R., Maguire C., Gilchrist S., Barrett L. J., Cross C. E., Possmayer F., Ennis M., Elborn J. S., Curry W. J., McGarvey J. J., Schock B. C. The use of Raman microscopy to determine and localize vitamin E in biological samples
Key Words: alpha-tocopherol tissue distribution lung tissue Raman mapping
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