SURFACE-ENHANCED RAMAN-SCATTERING (SERS) STUDY OF THE INTERACTION BETWEEN HEMATOPORPHYRIN AND GUANINE

The interaction between hematoporphyrin and guanine has been investigated by the Raman spectroscopic method. Irradiation of guanine solution mixed with hematoporphyrin was observed through the change in the Raman spectra. It was observed that the band at 1534 cm-1 shifted and the bands at 1274 cm-1 and 1190 cm-1 disappeared in the presence of hematoporphyrin. A prolonged irradiation time of five hours caused the SERS spectra of guanine to disappear. These results indicate that the guanine was modified in the photosensitized reactions in the presence of hematoporphyrin. We used SERS to study the photodynamic modification of nucleic acid base by hematoporphyrin. We found that illumination of guanine and adenine with the 514.5-nm argon-ion laser line in the presence of hematoporphyrin resulted in the selected degradation of guanine.