Showing papers by "Raymond Bonnett published in 2003"

Photophysical behaviour of an opp-dibenzoporphyrin (2,12-diethyl-3,13-dimethyldibenzo[g,q]porphyrin) in micelles and organic solvents.

Abstract: Photophysical parameters relevant to photodynamic therapy have been studied for a novel lipophilic opp-dibenzoporphyrin (DBP), 2,12-diethyl-3,13-dimethyldibenzo[g,q]porphyrin, in N,N-dimethylformamide and TX-100 micelles. The structure of DBP is intermediate between a porphyrin and a phthalocyanine and is associated with higher molar extinction coefficients in the red Q-bands than those found in the haematoporphyrin derivative currently used for photodynamic therapy. The ultrafast measurements on DBP in DMF revealed a fast (ps) lifetime for the second excited singlet state. Observed lifetimes of the first excited singlet state were found to be similar in DMF and TX-100 (12.2 and 14.7 ns), but excited triplet lifetimes were different in the two solvents (0.46 and 2.86 µs). The fluorescent quantum yields of DBP in DMF and TX-100 were twice that of free-base tetraphenylporphyrin and the singlet oxygen quantum yield in DMF and TX-100 was high (0.56–0.65). The combination of stable chemical structure, stronger red-absorption, high singlet oxygen quantum yields, and high fluorescent quantum yields suggests that DBP is an potential chromophore for applications in photodynamic therapy.

Determination of vascular-endothelial growth factor levels in serum from tumor-bearing BALB/c mice treated with photodynamic therapy.

Abstract: MATERIAL/METHODS We implanted a malignant tumour, BFS1 fibrosarcoma, into BALB/c mice and then treated them using a new photosensitizer, hydroxygallium (III) phthalocyanine tetrasulfonic acid tetrasodium salt, BON-6. The administration of this compound was followed by light irradiation using a halogen lamp at 680 nm. VEGF concentrations were measured in sera from the mice and compared to the time of tumor growth. RESULTS BON-6 was found to be effective in PDT. This feature was accompanied by low levels of VEGF after BON-6+PDT, and also prolongation of the time of survival of treated animals. The mice which received BON-6+PDT survived 83.8 days (SD 10.23). The mean survival time in control groups did not exceed 35 days. Additionally, measurement of tumor size showed total regression in single cases after BON-6+PDT. CONCLUSIONS PDT, by decreasing VEGF serum levels, may influence the capability of tumor tissue to form new vessels.

Determination of basic fibroblast growth factor levels in serum of tumor-bearing BALB/c mice treated with photodynamic therapy.

Abstract: In the present study we have checked whether photodynamic therapy (PDT) may influence concentration of basic Fibroblast Growth Factor (bFGF) in in vivo conditions. We have implanted malignant tumor, i.e. BFS1 fibrosarcoma into BALB/c mice and have them treated using well established photosensitizer, hematoporphyrin derivative and new compound, hydroxygallium (III) phthalocyanine tetrasulfonic acid tetrasodium salt, BON-6. The administration of those compounds was followed by light irradiation using a halogen lamp at proper wavelengths. Our results indicate that in vivo photodynamic therapy may cause a significant decrease in bFGF concentration and this phenomenon is accompanied by prolongation of survival of treated animals.