Absorption spectra of photosensitizers detected in vivo in tumor bearing mice

The absorption spectrum of disulphonated Aluminum Phthalocyanine (AlS2Pc) was measured in vivo in a murine tumor model by time-resolved reflectance (TRR). Mice bearing the L1210 leukemia were administered intraperitoneally 2.5 mg/kg body weight of AlS2Pc. Reflectance measurements were performed in the 650-695 nm range before and 4 h after the drug administration. The absorption coefficient at each wavelength was obtained by fitting the experimental curve using the diffusion equation. The spectrum of the photosensitizer was obtained as a difference between the absorption of treated and untreated mice. The absorption spectrum of AlS2Pc was peaked at 685 nm, showing a red-shift of approximately 15 nm with respect to the spectrum in aqueous solution.