In vivo fluorescence kinetics and localisation of aluminium phthalocyanine disulphonate in an autologous tumour model

Sulphonated phthalocyanines are studied as photosensitisers for photodynamic therapy of cancer. Their strong fluorescence and tumour-localising properties make them also potentially useful for detection of cancer by fluorescence. For this purpose, we have studied the fluorescence kinetics and localisation of aluminium phthalocyanine disulphonate (AIPcS(2)) in 4-nitroquinoline 1-oxide (4NQO)-induced dysplasia and invasive cancer of the oral mucosa of the hard palate in Wistar albino rats. Twenty-two rats were divided into six groups. Five groups were subjected to a 4NQO application period of 8, 12, 16, 20 or 26 weeks and one was a control group. The dysplasia varied from slight to severe and was correlated with the duration of the application period. All animals received a dose of 1 mu mol kg(-1) ALPcS(2) i.v. Fluorescence images were recorded via a specially designed 'palatoscope' with excitation at 460 +/- 20 nm for autofluorescence, 610 +/- 15 nm for AlPcS(2) fluorescence and detection of emission at 675 +/- 15 nm. After subtraction of the two images the specific AlPcS(2) fluorescence remained. AlPcS(2)-mediated fluorescence increased significantly when the severity of dysplasia increased (P