Experimental study on killing tumor cells by activation of hematoporphyrin derivatives by bi-frequency focal ultrasound in vitro

Tumor cells K562 were killed by the hematoporphyrin derivatives (HpD) activated by bi-frequency focal ultrasound in which a choice of irradiating parameter of ultrasound was tested by experiment. The effect of killing tumor cells was investigated by MTT method and compared with the contrast group. The results showed that the bi-frequency ultrasound exhibited an improved effect of killing tumor cells than single frequency ultrasound. It was 2-3 times higher than the single frequency ultrasound for the killing effect of tumor cells. After the irradiation of ultrasound, the cell-killing effect of hatching 16 h is better than that of hatching 4 h in the hatching tank. This might be due to delay of cell apoptosis.