| Singlet oxygen (1O2) is a major phototoxic component during Type-Ⅱ photochemical reaction of photodynamic therapy (PDT) and its generation is dependent on the availability of tissue oxygen. To examine the effect of oxygen concentration on1O2luminescence detection, two hydrophilic photosensitizer (PS), rose bengal (RB) and meso-metra (N-methyl-4-pyridyl) porphinetratosylate (TMPyP) were used as model PS. Irradiation was carried out using pulsed523nm laser light under hypoxic (2%,13%), normoxic (21%) and hyperoxic (65%) conditions. The spatial and spectral resolved1O2luminescence was measured by near-infrared camera and photomultiplier tube (PMT), respectively. Upon the irradiation, the emission signal mainly consisted of background scattering light, PS fluorescence and phosphorescence, and1O2luminescence. The PS phosphorescence was evidently dependent on the oxygen concentration and PS type, which resulted in the change of emission profile of1O2luminescence. The present study suggests that the effect of oxygen concentration on1O2luminescence detection is particularly important when the oxygen concentration is extremely low. |
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