Study on the absorption properties of sulphonated aluminum phthalocyanine in vivo and ex vivo in murine tumor models

The absorption spectrum of aluminum phthalocyanine with a mean degree of sulfonation of 2.1 (AlPcS2), previously measured in vivo in a murine tumor model (L1210 leukemia), showed a significant (10 to 15 nm) red shift with respect to the spectrum in solution and in vitro. To investigate whether this behavior was due to the peculiar model considered (ascitic tumor), the absorption line shape was evaluated in vivo noninvasively in a solid tumor (murine MS-2 fibrosarcoma) by means of time-resolved reflectance. The spectrum acquired in the range of 650 to 695 nm after the injection of 2.5 or 5 mg/kg body weight AlPcS2 confirms the red shift to 680 to 685 nm. Experiments performed ex vivo suggest that the spectral shift is related to the interactions of the drug with the extracellular biological substrate and depends on the sensitizer concentration. © 1997 Society of Photo-Optical Instrumentation Engineers.