FT-IR Spectroscopy Study in Early Diagnosis of Skin Cancer

Mid-infrared spectroscopy (4000-500 cm^-1) was used to analyze the spectral changes and differences of the characteristic absorption bands of the skin components due to cancer development for early clinical diagnosis.

Human biopsies from basal cell carcinoma, malignant melanoma, and nevus were used, while normal skin tissue served as a control.

The high quality of Fourier-transform infrared (FT-IR) spectra showed that upon cancer development the intensity of the absorption band at approximately 3062 cm^-1 was increased, indicating that most of the proteins had the configuration of amide B and the β-sheet protein structure predominated. The stretching vibration bands of vCH₂ in the region 2950-2850 cm^-1 were increased in melanoma and nevus, while were less pronounced in basal cell carcinoma due to the increased lipophilic environment. In addition, the intensity of a new band at 1744 cm^-1, which is assigned to aldehyde, was increased in melanoma and nevus and appeared as a shoulder in the spectra of normal skin. The absorption band of amide I at 1650 cm^-1 was split into two bands, at 1650 cm^-1 and 1633 cm^-1, due to the presence of both α-helix and random coil protein conformations for melanoma and nevus. This was confirmed from the amide II band at 1550 cm^-1, which shifted to lower frequencies at 1536 cm^-1 and 1540 cm^-1 for basal cell carcinoma and melanoma, respectively, indicating a damage of the native structure of proteins. The bands at 841 and 815 cm^-1, which are assigned to B-DNA and Z-DNA, respectively, indicated that only the bands of the cancerous Z-DNA form are pronounced in melanoma, while in BCC both the characteristic bands of B-DNA and Z-DNA forms are found.

It is proposed that the bands described above could be used as "diagnostic marker" bands for DNA forms, in the diagnosis of skin cancer.