MEASURE OF THE SINGLET OXYGEN YIELD GENER ATED FROM NAPHTHALOCYANINE PHOTOSENSITIZERS

Photodynamic therapy of cancer is a selective therapy applied to cance rous tissues with chemical agents, photosensitizers, stimulated by an appropriate illumination system. Our study is based on the following p hotosensitizers: bis(tri-n-hexylsiloxy) (compound I), bis(dimethylocta decylsiloxy) (II), bis(dimethylthexylsiloxy) (III), bis(tert-butyldime thylsiloxy) (IV) silicon 2,3-naphthalocyanine (SiNc) and zinc 2,3-naph thalocyanine (ZnNc) (V). A method of calibration, to obtain the single t oxygen (O-1(2)) quantum yield, has been developed with the use of a O-1(2) quencher, 9,10-diphenylanthracene (DPA). With this technique, w e have calculated O-1(2) quantum yields. The following values were obt ained: for compound I, Phi = 0.38; for II, Phi= 0.39; for III, Phi = 0 .39 and for IV, Phi = 0.22.