Method for monitoring singlet oxygen quantum yield in real time by time resolved spectroscopy measurement

The singlet oxygen quantum yield (ΦΔ) was monitored in real time through time resolved spectroscopy measurement, using gadolinium labeled hematoporphyrin monomethyl ether (Gd-HMME) as photosensitizer. According to the kinetics equations of singlet oxygen generation and reaction, ΦΔ was related to phosphorescence lifetime (τp). Through measuring τp of Gd-HMME in different oxygen conditions, the radiation transition property of first exited triplet state (T1) was monitored; combined with the triplet state quantum yield (ΦT) determined by linear fitting the ΦΔ, which was measured in different oxygen content using a relative measurement, ΦΔ can be determined in real time. The identification of anoxia during the treatment of photodynamic therapy (PDT) by this method is also presented.