中文摘要：

采用改进的Hummer方法合成氧化石墨烯,通过控制超声时间获得不同横向尺寸的纳米片,将其与大肠杆菌作用,发现氧化石墨烯的抗菌活性与其横向尺寸呈正相关,当氧化石墨烯平均横向尺寸为2.5μm时,大肠杆菌的失活率达到96.4%.以革兰氏阴性菌大肠杆菌、绿脓杆菌和革兰氏阳性菌金黄色葡萄球菌作为研究对象,考察氧化石墨烯的抗菌性能.结果表明,低浓度（≤100μg·mL^-1）时氧化石墨烯对革兰氏阴性菌的抑制作用强于对革兰氏阳性菌的抑制作用,当浓度达到200μg·mL^-1时,3种细菌失活率均能达到90%以上.最后通过原子力显微镜（AFM）观察大肠杆菌在氧化石墨烯作用下随时间的变化,发现大肠杆菌被氧化石墨烯纳米片包裹,其抗菌作用推测是通过氧化石墨烯片的氧化应激和阻隔营养物质的输送实现.

英文摘要：

Graphene oxide （GO） was synthesized by the modified Hummer method and the different lateral dimension of GO nanosheets were obtained under different ultrasonic irradiation time. After treating Escherichia coli with different lateral dimension of GO nanosheets, the antibacterial activity of GO has positive correlation to its lateral size. The viability of Escherichia coli cells decreased by 96.4% when the average lateral size of GO is 2.5 μm. Taking gram negative bacteria Escherichia coli and Pseudomonas aeruginosa as well as gram positive bacteria Staphylococcus aureus as the research object, the antibacterial activities of the optimal GO nanosheet with a series of concentrations were carried out. The results showed that the antibacterial activity of GO against gram negative bacteria was higher than that of gram positive bacteria at low concentration （4 100 μg·mL^-1）. When the concentration of GO reached 200μg·mL^-1 , the inactivation ratios of all the three bacterial could reach more than 90%. Finally, the time-dependent morphology change of Escherichia coli was observed by atomic force microscopy （AFM）, which showed that Escherichia coli ceils were covered by GO nanosheets, and the cells were probably killed by oxidative stress and the blocking of nutrients＇ transportation by GO nanosheets.