Image of the distribution profile of targets in skin by Raman spectroscopy‐based multivariate analysis

Raman spectroscopic imaging is a label‐free spectral technology to investigate the distribution of transdermal targets in skin. However, it is difficult to analyze low content of analytes in skin by direct imaging analysis. Combining Raman mapping technology with multiple linear regression algorithms, concentration contribution factor of targets in ex vivo human skin tissue at every point has been calculated. The distribution profiles are visualized as heat maps demonstrating the targets levels in different skin layers. This method has been successfully employed to investigate the vibrational imaging of distribution of hyaluronic acid and lidocaine in skin. Moreover, three dimensional (3D) images of the penetration profiles of hyaluronic acid with different molecular weight have been obtained. The results from 3D images were in good agreement with these from two‐dimensional images, indicating that this method was a reliable way for monitoring the distribution of targets in skin.