Fluorescence photometric techniques for determination of microscopic tissue distribution of phthalocyanine photosensitizers for photodynamic therapy
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Detection of photosensitizers at the microscopic level is fundamental to understanding the mechanism of photodynamic therapy. Fluorescence microscopy is capable of high sensitivity using photometric detectors which enable quantitative measurements of photosensitizer fluorescence intensity. The use of a cooled slow-scan CCD (charge-coupled device) imaging system is particularly suitable for this application since the image can be time-integrated by the CCD sensor. Using the digital image processing a wide range of signal levels may be quantitatively compared, and the high sensitivity eliminates interference from photobleaching. In this work a CCD camera system has been used to obtain fluorescence images of aluminium sulphonated phthalocyanine in normal and malignant colonic rat tissue sections. Correlation of relative fluorescence intensities with concentration is discussed with regard to phthalocyanine sensitizers.
KeywordsPhotodynamic therapy Phthalocyanine Fluorescence microscopy
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