FT‐Raman spectroscopic study of thoracic aortic wall subjected to uniaxial stress

Abstract

The combination of Fourier transform-Raman spectroscopy and uniaxial tensile tests (in MTS Synergie 100 testing machine) was used to investigate microstructural changes in the secondary protein structure of the aortic wall under different levels of stress. The spectroscopic analysis clearly shows differing tension thresholds for material excised in two directions: circumferential and longitudinal. This is confirmed by the results of macroscopic mechanical analyses. The application of strain does not lead to any noticeable change in the bandwidths of the Raman bands. The stress-controlled Raman band analysis shows that the modes at 938 cm −1 assigned as C α -C of the α-helix, 1660 cm −1 amide I (the unordered structure of elastin) and 1668 cm −1 amide I (the collagen triple helix) undergo wavenumber shifting, but the bands at 1004 cm −1 assigned to the phenyl ring breathing mode and 2940 cm −1 to the ν (CH 3 ) and ν (CH 2 ) modes are not affected during the elastic behaviour. A clear correlation between Raman band shifting and the level of mechanical stress has been established. Elastin alone participates in the transmission of low stresses in the circumferential direction, whereas both elastin and collagen take part in the transmission of physiological and higher stresses.

Recent advances in linear and nonlinear Raman spectroscopy. Part V

“…The combination of Fourier transform (FT)‐Raman spectroscopy and uniaxial tensile tests was used by Hanuza et al . to investigate microstructural changes in the secondary protein structure of the aortic wall under different levels of stress . The Raman spectroscopic analysis clearly shows differing tension thresholds for material excised in two directions: circumferential and longitudinal.…”

“…[182] Polarized IR and Raman spectra of Na 3 Li(MoO 4 ) 2 -6H 2 O single crystal were measured by Hanuza and coworkers. [183] The results for the spontaneous Raman scattering were used in the analysis of the stimulated Raman spectra of the material studied [184] Raman and IR spectroscopy were used by Tomic and coworkers for the characterization of several minerals in morphologically similar vertisol sequences from Kizevak (Serbia). [185] Raman spectroscopy was used by Wehrmeister et al to study vaterite samples of biological, geological and synthetic origin.…”

A Reactive Inelasticity Theoretical Framework for Modeling Viscoelasticity, Plastic Deformation, and Damage in Fibrous Soft Tissue

“…Several studies support a correlation between mechanical loading and the state of molecular bonding as described below. Fourier-transform Raman spectroscopy during tendon's incremental stress relaxation tests [63], and thoracic aortic wall's ramp-to-failure [64] show that the protein conformation is highly dependent on mechanical loading. Additionally, when overloaded, collagen fibrils show local deformities (kinks) that contain denatured-collagen-rich regions [65,66].…”

Specific Applications of Vibrational Spectroscopy in Biomedical Engineering

“…Spectroscopic analysis shows differing tension thresholds for rich collagen material (ligaments, tendons) and tissues containing a high amount of elastin (blood vessel walls, skin). Moreover, the stress-strain plots and the Raman spectra recorded for the circumferentially and longitudinally oriented samples of aortic wall show significant differences (Hanuza et al, 2009). …”

“…This technique has been applied for such tissues as tendon, blood vessel walls and skin. Simple correlation between the Raman spectroscopic data and mechanical relations can be established (Hanuza et al, 2009;Winchester et al, 2008). Temperature, pH, presence of salts, electromagnetic radiation exposure and organic solvents modify biological compounds, inducing specific conformational changes which are relevant for the understanding of their functions (Parker, 1983).…”