Ex vivo confocal Raman microspectroscopy of porcine dura mater using 532 nm excitation and optical clearing
Ali Jaafar,1,2,3 Ágnes N. Szokol1 , Malik H. Mahmood1,2,4, István Rigó1 , Anton Y. Sdobnov5,6 , Valery V. Tuchin,5,7,8 and Miklos Veres1
1Institute for Solid State Physics and Optics, Wigner Research Center for Physics, Hungary; 2Institute of Physics, University of Szeged, Hungary; 3Ministry of Higher Education and Scientific Research, Iraq; 4Physiology Department, College of Medicine University of Misan, Iraq; 5Science Medical Center, Saratov State University, Russia; 6Optoelectronics and Measurement Techniques Laboratory, University of Oulu, Finland; 7Laboratory of Laser Diagnostics of Technical and Living Systems, Institute of Precision Mechanics and Control of the Russian Academy of Sciences, Russia
8Interdisciplinary Laboratory of Biophotonics, National Research Tomsk State University, 36 Lenin ave, 634050, Tomsk, Russia
Abstract
The confocal Raman microspectroscopy (CRM) spectra of ex vivo porcine dura mater was examined using 532 nm excitation wavelength in-depth from 0 to 200 μm. The Optical Clearing (OC) with different treatment times of 0, 5, 10, 15 and 30 min showed that the optical properties of porcine dura mater can be controlled to a maximum depth of 200 μm, and the effect of 30 min glycerol treatment of porcine dura mater made the deep-located regions available for investigations. OC could increase the intensity of all principal collagen bands. The resonant Raman enhancement of some Raman bands was observed during depth profiling measurements of OC treated dura mater. It was clearly seen that the optical clearing technique combined with CRM at 532 nm wavelength allowed one to preserve the high probing depth, signal-to-noise ratio and spectral resolution simultaneously. In addition, we decided to used 532 nm excitation wavelength from a practical perspective, as for medical diagnostics and treatment it is easier to use the visible green laser during surgery to figure out the resection tumor based on vibrational features because the laser spot will be visible. Moreover, the resonance enhancement due to intrinsic tissue chromophores—carotenoids for visible laser increases the detection limit of the method.
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ALI JAAFAR
Institute for Solid State Physics and Optics, Wigner Research Center for Physics, P.O. Box 49, Budapest, H-1525, Hungary
Hungary
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