Preparation Of TiO₂-based Nanodots Films And Their Light-induced Cell Detachment Performance

Cell sheet technology is one of the frontier issues in the research of tissue engineering. Such technology needs a large amount of cell sheets with high activity. Therefore, the appropriate culture substrate and method of in vitro cell sheet harvest become the key parts in cell sheet technology. When cell contacts with the surface of a solid material, protein is considered as a intermedium. Therefore, the surface properties of materials that affect protein adsorption, such as wettability, crystalline phase, chemical composition, will definitely affect the subsequent responses of cells.In this thesis, based on the study of light-induced cell detachment from anatase TiO2 nanodots film, the surface properties of TiO2 nanodots film were modified through ZnO incorporation and crystalline phase variation of TiO2, so that the biological performance could be improved. The main researches focus on the film morphology, chemical composition, crystalline phase, the optical absorption edge, surface wettability and cell adhesion, spreading, proliferation properties. Based on these results, the films were used for light-induced cell detachment finally. The activity of detached cells was tested and the mechanism of light-induced cell detachment was explored. The main contents and conclusions are as follows:(1) Preparation and characterization of hierarchical TiO2/ZnO composite nanodots filmFirst of all, TiO2 nanodots films were prepared by a self-assembly method. Then ZnO was deposited on TiO2 nanodots films to form hierarchical TiO2/ZnO composite nanodots films. All the films showed excellent cell compatibility and the sample with proper ZnO content promoted the proliferation of MC3T3-E1 cells. After 20min UV365 irradiation, cells could be rapidly detached from films and the sample with proper ZnO content showed higher cell detachement ratio than pure TiO2. The detachment ratio reached 89.3%.(2) Preparation and characterization of TiO2/ZnO composite nanodots filmMixed Ti and Zn precursor sol with different Zn/Ti molar ratio was first prepared. TiO2/ZnO composite nanodots films were prepared on quartz glass substrates through phase separation self assembly. With increasing Zn amount, the crystallinity of nanodots films decreased. All the films showed good cell compatibility and light-induced cell detachment performance. ZT0.03 sample showed the highest detachment ratio. After 20min UV365 irradiation, the ratio reached 91.0%.(3) Preparation and characterization of rutile/anatase composite TiO2 nanodots filmQuartz substrates were coated with a layer of TiO2 sol through phase separation self assembly. Then the samples were heated at different temperatures (500℃,700℃, 900℃ and 1100℃) to obtain rutile/anatase composite TiO2 nanodots film. All the films showed good cell compatibility and TiO2 nanodots film containing more rutile phase had a higher efficiency of light-induced cell detachment. That is ascribed to the structural variations of protein molecules adsorbed before and after UV365 irradiation.Intact MC3T3-E1 and NIH3T3 cell sheets could be obtained easily by UV365 irradiation on such nanodots films. Readhesion of detached cells and the live-dead staining of cell sheets showed that the cells detached by UV365 irradiation maintained high activity. It is expected such cell sheet could be utilized in tissue engineering. The present work could be utilized to optimize light-induced cell detachment behavior.