By using 1,3-diphenylisobenzofuran (DPBF) as a singlet-oxygen trap, the mechanism of actination of hematoporphyrin (HP) by ultrasound was investigated.By measuring the relative loss of DPBF by an ultraviolet-visible light spectrophotometer, singlet-oxygen is proved to generate in the solution of HP and DPBF after insonation by ultrasound.Experimental results show that the relative loss of DPBF increases with the insonation time and ultrasound intensity, which supports the argument that singlet-oxygen is generated when HP is activated by ultrasound.An approach dividing the sonoluminescence from the sound field by using isotropic light trap is presented, and it is used to determine whether fluorescence or high temperature caused by ultrasound cavitaion will activate HP so as to produce singlet-oxygen.By comparison of the above results with those irradiated by white light, it is shown that sonoluminescence is not strong enough to activate HP although it can sensitize photo plate.

Key words: hematoporphyrin and its derivatives, ultrasound activation, singlet-oxygen, 1,32diphenylisobenzofuran(DPBF)