In an early study Jani et al. administred rutile TiO2 (500 nm) as a 0.1 ml of 2.5 % w/v suspension (12.5 mg/kg BW) to female Sprague Dawley rats, by oral gavage daily for 10 days and detected presence of particles in all the major gut associated lymphoid tissue as well as in distant organs such as the liver, spleen, lung and peritoneal tissue, but not in heart and kidney. The distribution and toxicity of nano- (25 nm, 80 nm) and submicron-sized (155 nm) TiO2 particles were evaluated in mice administered a large, single, oral dosing (5 g/kg BW) by gavage. In the animals that were sacrificed two weeks later, ICP-MS analysis showed that the particles were retained mainly in liver, spleen, kidney, and lung tissues, indicating that they can be transported to other tissues and organs after uptake by the gastrointestinal tract. Interestingly, although an extremely high dose was administrated, no acute toxicity was observed. In groups exposed to 80 nm and 155 nm particles, histopathological changes were observed in the liver, kidney and in the brain. The biochemical serum parameters also indicated liver, kidney and cardiovascular damage and were higher in mice treated with nano-sized (25 or 80 nm) TiO2 compared to submicron-sized (155 nm) TiO2. However, the main weaknesses of this study are the use of extremely high single dose and insufficient characterisation of the particles.
Unfortunately, we studied that all of the above methods are employed after machining or forming, and they require a long process chain and costly production types of equipment [21–24]. Therefore, we proposed a titanium alloy implant preparation process that integrated with cutting and surface modification. The oxygen-rich atmosphere increases the partial pressure of oxygen in the oxidizing environment, and the heat generated during the cutting process increases the temperature and the rate of the oxidation. It uses the cutting heat and oxygen-rich atmosphere generated during the cutting process to form the oxide film (TiO2) to improve the corrosion resistance of the titanium alloy. The experimental equipment is shown in Figure 2. Since the cutting temperature is the most important factor in the oxide film formation process, this paper carried out researches based on theoretical analysis and experimental investigation to acquire an ideal temperature range for the cutting process to achieve the oxide layer.
Infrared spectra were performed (from 400 to 4000 cm−1) in vitamins@P25TiO2NPs samples and the vitamins alone as controls, employing a Nicolet AVATAR 360 Fourier transform infrared spectrophotometer.