纳米TiO2光催化杀灭大肠杆菌的超微结构研究

在近紫外光的照射下，纳米TiO2具有较强的光催化灭茵效果。用透射电子显微镜较完整地研究纳米TiO2光催化杀灭大肠杆菌的超微结构变化。结果表明，纳米TiO2可直接或间接作用于大肠杆菌；光催化过程中产生的氢氧自由基等活性氧类物质可导致大肠杆菌的外壁和质膜严重破损、断裂；胞浆流出；细胞质凝聚；类核区解体和丝状染色质消失。本研究为探讨纳米TiO2光催化灭茵机理提供了直观的证据。

Ultrastructural studies on the photocatalytical sterilizationusing titanium dioxide nanoparticles

Under the irradiation of near-UV light, the TiO_2 nanoparticles exhibit strong photocatalytic bactericidal activities. During the photocatalyic process, the ultrastructures of Escherichia coli (E. coli) have been studied in detail by transmission electron microscope (TEM). The results indicate that TiO_2 nanoparticles can act on E. coli directly and indirectly. The reactive oxygen species such as hydroxyl radical produced in the photocatalysis result in the disruption of the bacterial cell wall and cytoplasmic membrane, the leakage of the cell contents and the agglomeration of cytoplasmic matrix. The disaggregated nucleoid, the disappeared chromosome DNA and the decomposed of endotoxin were also observed in the killed cells of E. coli . The ultrastructural studies provide the evidence for understanding the cell killing mechanism of the TiO_2 photocatalyst.