Fig. 6

Trypan blue staining for cell viability. The results showed that ultrasound treatment for 60 s and UTMD treatment for 60 s had no significant effect on cell viability. With the further increase of UTMD treatment time from 60 to 180 s, cell viability decreases from 86.33 ± 1.89% to 38.00 ± 1.63% after 48 h of treatment. All values are expressed as the mean ± SD. **P < 0.01; n = 3