Photodynamic treatment (PDT) causes a significant increase in the permeability of the blood-brain barrier (BBB) in healthy mice. Using different doses of laser radiation (635 nm, 10-40 J/cm²) and photosensitizer (5-aminolevulinic acid – 5-ALA, 20 and 80 mg/kg, i.v.), we found that the optimal PDT for the reversible opening of the BBB is 15 J/cm² and 5-ALA, 20 mg/kg, exhibiting brain tissues recovery 3 days after PDT. Further increases in the laser radiation or 5-ALA doses have no amplifying effect on the BBB permeability, but are associated with severe damage of brain tissues. These results can be an informative platform for further studies of new strategies in brain drug delivery and for better understanding of mechanisms underlying cerebrovascular effects of PDT-related fluorescence guided resection of brain tumor.

Antibacterial photodynamic therapy is a pioneering method for the inactivation of pathogenic bacteria. Four tetra alkyl-substituted cationic phthalocy

Tissue polarimetry holds great promise to improve the effectiveness of conventional cancer diagnostics and staging, being a fast, minimally invasive, and low-cost optical technique. We introduce an enhanced diagnostic method for ex vivo colon specimens assessment by utilizing Stokes and Mueller matrix polarimetry. The proposed method makes use of experimental Mueller matrices, measured from healthy and tumor zones of a colon specimen, as input data for post-processing algorithms that include physical realisability filtering, symmetric decomposition and estimation of various polarization and depolarization metrics for colon specimen diagnostics. We validated our results with the gold standard histological diagnostics provided by pathologists. It was found that the Stokes-Mueller matrix polarimetry, combined with the appropriate filtering, decomposition algorithms and polarization/depolarization metrics calculations provides relevant optical markers of the colon tissue pathological conditions (healthy versus cancer), as confirmed by histopathology analysis. This approach potentially provides physicians with valuable and complementary information that holds promises in helping with the diagnostics of colon tissue specimens.

A short review will be presented of the recent clinical achievements in the field of skin autofluorescence and exogenous fluorescence tumor detection. Photosensitizers used for exogenous photodetection of cutaneous lesions will be discussed from the point of view of their photodynamic diagnostic properties and their advantages and drawbacks associated with clinical applications. A survey on various results of detection and differentiation of the fluorescent data observed from malignant cutaneous lesions will be summarized and an optimization of the skin cancer detection techniques based on fluorescence diagnostics will be analyzed and discussed. A short presentation will be given of own experimental results and clinical experience acquired in the past decade in the autofluorescence diagnostics of different benign, dysplastic, and malignant skin neoplasia. The origins of the fluorescence spectra, their peculiarities, the feasibility of clinical tumor detection, and differentiation needs will also be discussed.