A pilot study for distinguishing basal cell carcinoma from normal human skin tissues using visible resonance Raman spectroscopy

Aim: The aim of the study is to test visible resonance Raman (VRR) spectroscopy for rapid skin cancer diagnosis,and evaluate its effectiveness as a new optical biopsy method to distinguish basal cell carcinoma (BCC) from normal skin tissues.Methods: The VRR spectroscopic technique was undertaken using 532 nm excitation. Normal and BCC human skin tissue samples were measured in seconds. The molecular fingerprints of various native biomolecules as biomarkers were analyzed. A principal component analysis - support vector machine (PCA-SVM) statistical analysis method based on the molecular fingerprints was developed for differentiating BCC from normal skin tissues.Results: VRR provides a rapid method and enhanced Raman signals from biomolecules with resonant and nearresonant absorption bands as compared with using a near-infrared excitation light source. The VRR technique revealed chemical composition changes of native biomarkers such as tryptophan, carotenoids, lipids and proteins.The VRR spectra from BCC samples showed a strong enhancement in proteins including collagen type I combined with amide I and amino acids, and a decrease in carotenoids and lipids. The PCA-SVM statistical analysis based on the molecular fingerprints of the biomarkers yielded a 93.0% diagnostic sensitivity, 100% specificity, and 94.5%accuracy compared with histopathology reports.Conclusion: VRR can enhance molecular vibrational modes of various native biomarkers to allow for very fast display of Raman modes in seconds. It may be used as a label-free molecular pathology method for diagnosis of skin cancer and other diseases and be used for combined treatment with Mohs surgery for BCC.

Photodamage to Pigment in the Photosystem Ⅱ Reaction Center D1/D2/Cytochrome b559 Complex

Strong light （800μmol photons/m^2 per s）-induced bleaching of the pigment in the isolated photosystem Ⅱ reaction center （PSII RC） under aerobic conditions （in the absence of electron donors or acceptors） was studied using high-pressure liquid chromatography （HPLC）, absorption spectra, 77K fluorescence spectra and resonance Raman spectra. Changes in pigment composition of the PSII RC as determined by HPLC after light treatment were as follows： with Increasing illumination time chlorophyll （Chl） a and β-carotene （β-car） content decreased. However, decreases in pheophytin （Pheo） could not be observed because of the mixture of the Pheo formed by degraded chlorophyll possibly. On the basis of absorption spectra, it was determined that, with a short time of illuminatlon, the initial bleaching occurred maximally at 680 nm but that with Increasing Illumination time there was a blue shift to 678 nm. It was suggested that P680 was destroyed Initially, followed by the accessory chlorophyll. The activity of P680 was almost lost after 10 mln light treatment. Moreover, the bleaching of Pheo and β-car was observed at the beginning of illumination. After Illumination, the fluorescence emission Intensity changed and the fluorescence maximum blue shifted, showing that energy transfer was disturbed. Resonance Raman spectra of the PSII RC excited at 488.0 and 514.5 nm showed four main bands, peaking at 1 527 cm^-1 （υ101）, 1 159 cm^-1 （υ2）, 1 006 cm^-1 （υ3）, 966 cm^-1 （υ4） for 488.0 nm excitation and 1 525 cm^-1 （υ1）, 1 159 cm^-1 （υ2）, 1 007 cm^-1 （υ3）, 968 cm^-1 （υ4） for 514.5 nm excitation. It was confirmed that two spectroscopically different β-car molecules exist In the PSII RC. After light treatment for 20 mln, band positions and bandwidths were unchanged. This indicates that carotenoid configuration Is not the parameter that regulates photoprotectlon in the PSII RC.