Eosin oxygen effects

There was a slight effect of the oxygen concentration ([02] = 10-3 to 10-2 mole/liter) on A02 when eosin and fluorescein were used as sensitizers. Assuming that this is due to the relatively long lifetimes of the corresponding excited singlet states which may allow these states to interact with oxygen, crude values of k6 were calculated (see Table II). 

The localization of the sensitizer has a significant effect on the photodynamic activity. Eosin is scarcely taken up by cells, and Pooler and Girotti [131] report that Eosin isothiocyanate is 50-100 times more efficient for inducing photohemolysis of human erythrocytes. The spectral properties and quantum yields for singlet oxygen production are identical for both compounds. Therefore, they attribute the difference in photodynamic activity to the ability of the isothiocyanate derivative to bind covalently to band 3 protein. 

Scheme 1.1. Effects of heat, light, and acid in the presence of oxygen on the dimeric Strychnos alkaloids. Reagents a. O2 + A, or O2 + hv b. O2 + hv + eosin, or O2 + pyr/AcOH c. O2, H30. ...

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