Decrimping: The First Stage Of Collagen Thermal Denaturation Unraveled By In Situ Second-Harmonic-Generation Imaging

With polarized and time-lapsed second-harmonic-generation (SHG) imaging, three distinct thermodynamic stages are revealed during heating of collagenous tissue. In the first "decrimping" stage, SHG intensity remains unchanged while the characteristic crimp pattern of collagen fiber disappears. The intactness of underlying fibrils is confirmed by unaffected second-order susceptibility, suggesting decrimping is related to the breakage of cross-linking between collagen fibrils. In the latter stages, significant SHG decrease is observed, providing quantification to collagen thermal denaturation. This study manifests the benefits of adopting SHG for understanding the thermal response of collagen, and will be useful toward better thermal therapy design. (C) 2011 American Institute of Physics. [doi:10.1063/1.3578191]