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Effect of Photosensitizer Delivery System and Irradiation Parameters on the Efficiency of Photodynamic Therapy of B16 Pigmented Melanoma in Mice
Author(s) -
Biolo Roberta,
Jori Giulio,
Soncin Marina,
Rihter Boris,
Kenney Malcolm E.,
Rodgers Michael A. J.
Publication year - 1996
Publication title -
photochemistry and photobiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.818
H-Index - 131
eISSN - 1751-1097
pISSN - 0031-8655
DOI - 10.1111/j.1751-1097.1996.tb03018.x
Subject(s) - photosensitizer , photodynamic therapy , irradiation , melanoma , cancer research , chemistry , photochemistry , medicine , physics , organic chemistry , nuclear physics
— Previous studies (Biolo et al., Photochem. Photobiol. 59, 362‐365, 1994) showed that liposome‐delivered Si(IV)‐na‐phthalocyanine (SiNc) photosensitizes B16 pigmented melanoma subcutaneously transplanted in C57 mice to the action of 776 nm light. However, the efficacy of the phototreatment was limited by a lack of selectivity of tumor targeting by SiNc as well as by incomplete necrosis of the neoplastic mass. The present investigations show that the use of a different delivery system (Cremophor emulsion vs liposomes of dipalmitoylphosphatidylcholine) causes no significant increase in the selectivity of tumor targeting for three injected doses of SiNc (0.5, 1, 2 mg/kg). However, upon 776 nm light irradiation (300 mW/cm 2 ; 520 J/cm 2 ), the delay in the rate of tumor growth was maximal (7‐8 days) for the highest naphthalocyanine dose. On the other hand, a remarkable improvement in the tumor response was obtained by inducing an intratumoral temperature increase to 44°C immediately after PDT. The thermal effect appeared to be due to photoexcitation of melanin by 776 nm light (550 mW/cm 2 ; 520 J/cm 2 ) and subsequent partial conversion of absorbed energy into heat.