The influence of the number of shock waves and the energy flux density on the Raman spectrum of collagen type I from rat

Shock waves are used to treat musculoskeletal injuries and trigger the body's mechanisms to initiate healing; however, the cellular and molecular working mechanisms are not fully known. Raman spectroscopy may be a useful tool to provide information on structural changes. Solid collagen type I from rat tail (> 90% pure) was suspended in water and was exposed in vitro to different numbers of shock waves and energy flux densities. Raman spectra were recorded at 2 h, 1 week, and 3 weeks after shock-wave treatment. The spectral analysis indicated that varying the number of shock waves and the energy flux density induced molecular changes in the collagen structure. Varying the energy flux density induced more significant changes than modifying the number of shock waves; however, in most cases, the collagen recovered its original conformation 3 weeks after treatment. A significant decrease in the relative intensities of the conformational bands, which include amide I, amide III, and stretching C-C, was observed at different energy flux densities. In many clinical cases, the natural repair of tissue is improved after shock-wave treatment. Raman spectroscopy revealed that varying the energy flux density of the shock waves applied to rat collagen type I induced strong conformational molecular changes. Approximately 2-3 weeks after shock-wave treatment, a phase of molecular ordering tending to a recovering molecular sequence repair was observed.