In vitro secretion of TNF-α from bone marrow mononuclear cells incubated on amino group modified TiO2 nano-composite under ultrasound irradiation

It is recently known that titanium dioxide (TiO2) can be excited by ultrasound and release of OH radicals on the surface. In this study, secretion of an indirect angiogenic factor, tumor necrosis factor-α (TNF-α), from bone marrow mononuclear cells (BM-MNC) incubated on amino group modified TiO2 nano-particles covalently coated on polyester fabric (TiO2/PET) under ultrasonic irradiation was examined in vitro. The cell viability and TNF-α secretion were measured under ultrasound irradiation condition with 255 mW/cm2 of intensity, which is below the highest output (1 W/cm2) specified in the safety standard for a medical ultrasonic diagnostic apparatus. The living cell number on the TiO2/PET and original PET with/without continuous ultrasound irradiation was unchanged statistically by ANOVA test. TNF-α secretion level from BM-MNC remarkably increased on the TiO2/PET under ultrasonic irradiation without cell damage. It was, therefore, thought that the high level of TNF-α secretion on the TiO2 nano-composite by ultrasound irradiation was due to oxidative stress induced from OH radicals on TiO2.