Raman spectroscopy combined with SHG gives a new perspective for rapid assessment of the collagen status in the healing of cutaneous wounds

Accurate and rapid assessment of the healing status of a wound in a simple manner would enable clinicians to diagnose wounds in time and promptly adopt appropriate treatments for nonhealing wounds. Traditional histologic and biochemical characterization of biopsied wound tissue is complicated to operate, slow and complex to interpret. Here we applied three testing methods and drew a conclusion that Raman microspectroscopy combined with SHG is a comprehensive way to trace the regeneration status of collagen during wound repair from both aspects of quantity and morphology. Four slices of one sample at different locations were made and three spots of each slice were detected. The average was used as the last spectrum. Spectra of wound samples at different time points show an obvious increase in the special Raman region of collagen fingerprints (1672, 1641, 1274, 1244, and 1180 cm(-1)) and C-C\C-H vibration of total proteins (1445, 941 cm(-1)) as the time duration for healing was prolonged. Besides, we used two analytical methods to analyze Raman spectra: the 1665/1445 cm(-1) band area ratio and principal component analysis, respectively. The former reflects collagen accumulation during wound healing, while the latter shows a successful cluster of samples at different healing status. Our results demonstrate that Raman spectroscopy combined with SHG may be used as a complementary tool for in situ biochemical characterization in wound healing studies and clinical diagnosis.