Fundamental study on activation of aminated titanium dioxide composite by low-intensity focused ultrasound irradiation in anti-infective catheter system

It has been reported that the hydroxyl (OH) radical is produced by irradiating ultrasound to titanium dioxide (TiO2). On the other hand, infection at the exit site of catheter retained in the body has become a serious problem. Therefore, we are developing a novel anti-infective catheter system in which the exit site of a catheter is covered with an aminated titanium dioxide (AmTiO2) composite, which consists of AmTiO2 nanoparticles immobilized on a substrate and exhibits cell adhesiveness, and the anti-infective effect (OH radical production) is induced by irradiating lowintensity focused ultrasound (LIFU) to the composite. In this study, the ability to activate TiO2 nanoparticles by ultrasound irradiation was verified in a preliminary experiment, and then the feasibilities that the AmTiO2 composite is activated and that the OH radical is produced by LIFU irradiation were verified by dye decomposition experiment and dihydroxybenzoic acid (DHBA) measurement. In addition, as a trigger for activating the AmTiO2 composite by LIFU irradiation and for producing the OH radical, the decrease in cavitation threshold was suggested.