中文摘要：

通过改进的Hummers法制备氧化石墨烯（G0），利用酰胺化反应将端基为氨基的六臂聚乙二醇（PEG）连到氧化石墨烯表面，改善其水溶性和生物相容性．原子力显微镜（AFM）数据表明所制备的GO．PEG尺寸小于250nm，稳定性试验证明GO．PEG在水和PBS缓冲液中可以很好地分散．利用制备的GO．PEG作为药物载体，通过物理共混的方法负载疏水性抗肿瘤药物——冬凌草甲素．紫外光谱法测得载药率高达105％，远高于一般其他的药物载体．选择肺癌细胞A549和乳腺癌细胞MCF．7对载药体系的细胞毒性进行了研究，结果表明即使在高达100mg／L的浓度下培养48h，载体GO．PEG对两种细胞仍然具有很小的毒性（相对细胞存活率〉85％），而通过载体负载后冬凌草甲素的疗效有所增强，对细胞具有更大的杀伤作用．

英文摘要：

Graphene oxide （GO） was prepared by modified Hummers method firstly. In order to improve its water solubility and biocompatibility, 6-armed PEG was grafted onto GO via an amidation process. The size of GO-PEG was less than 250 nm and stability test indicated excellent dispersibility of GO-PEG in water and PBS buffer. Furthermore, oridonin, a widely used cancer chemotherapy drug, is adsorbed onto GO-PEG via blending. The drug loading ratio was determined to be as high as 105%, which was much higher than other common drug carriers. A549 lung cancer cell and MCF-7 breast cancer cell were chosen to study the cytotoxicity of GO-PEG/oridonin, GO-PEG, and free oridonin. The results demonstrated that GO-PEG did not show obvious toxicity （relative cell viability〉85%）, even cultivated for 48 h at a relatively high concentration of 100 mg/L. Compared to oridonin, the GO-PEG/oridonin nanocarder shows higher cytotoxicity in A549 and MCF-7 cells.