Detection of cutaneous melanin based on Raman spectroscopy with optical coherence tomography localization

Abstract

Melanoma skin cancer is one of the most dangerous types of cancer and responsible for more than half of the skin cancer-related deaths. Common methods for skin cancer detection are dermoscopy and visual inspection, the accuracy of which is greatly influenced by the training and experience of the physician. In some extreme cases, histological findings, which are considered the gold standard for detecting skin cancer, might also cause a debate among competent clinicians. To achieve accurate non-invasive skin cancer diagnostics, a dual-mode optical biopsy system made up of a Raman spectrometer and an OCT system was built. OCT morphological images enable precise localization of the position and depth of lesions for subsequent Raman detection. Skin models were generated by dissolving synthetic melanin in dimethyl sulfoxide (DMSO) and applying it to fresh porcine skin samples to investigate the influence of melanin concentration on skin spectra. The amide-I band and the CH2-deformation band detected by using Raman spectroscopy had a lower intensity in the spectra of the samples treated with melanin, which may imply that the addition of melanin promotes the breakdown of proteins and lipids. The intensities of the CH2 twist and C-C stretch bands increased compared to the drop of the aforesaid bands. Given that these two structures are often present in phospholipids, which are the fundamental components of cell membranes, one possible explanation is that melanin has less influence on membranes than on biological macromolecules.