经多聚赖氨酸修饰后的云母表面形貌及细胞DNA的AFM观察

The AFM Observation of the Morphology of Mica Surface and Cellular DNA Modified by Poly-lysine

通过原子力显微镜(AFM)观察并分析多聚赖氨酸在不同浓度和不同修饰方式下云母表面的形貌,选择适于观察细胞DNA的最佳修饰条件.使用不同浓度的多聚赖氨酸对云母表面进行直接滴加和镀膜两种方式进行处理后,AFM观察其对云母表面形貌的影响以及DNA分子在修饰后的云母表面沉积情况.结果显示:多聚赖氨酸直接滴加至云母上时,其表面会形成大小不同的颗粒与聚集体;采用镀膜方式后,云母表面颗粒数量明显减少,颗粒粒度亦明显变小,经镀膜处理的云母表面更为平坦,表面平均粗糙度(Ra)更小;降低多聚赖氨酸浓度会使云母表面粗糙度减小,多聚赖氨酸浓度降至0.1μg/mL及以下时云母表面的粗糙度不再有明显变化.经0.1μg/mL多聚赖氨酸镀膜处理云母后,DNA分子在其上有较好的铺展.与直接滴加的方式相比,采用多聚赖氨酸镀膜方式处理云母表面,可降低粗糙度.0.1μg/mL多聚赖氨酸镀膜后,细胞DNA在云母表面分散较更好,适于AFM对DNA分子的观察和相关研究.

This study aims to investigate the optimal observation condition by atomic force microscope（AFM） for cellular DNA through the AFM observation and analysis of the morphology of mica surface under the condition of different concentrations of poly-lysine modification.Our method is to make an AFM observation of the morphology of mica surface and the deposition of cellular DNA on mica when poly-lysine of different concentrations is directly added to or coated on freshly cleaved mica.The result shows that particles of various size and aggregation were visible when poly-lysine was directly added to the mice.However,the number and granularity of particles and the roughness（Ra） were significantly reduced after poly-lysine was coated on the mica.The surface of mica coated with poly-lysine was smoother.The roughness was decreased with the lower concentration of poly-lysine.The roughness did not show a significant change when the concentration of poly-lysine was not higher than 0.1 μg/mL.DNA molecular were better spread when the surface of mica was coated with 0.1 μg/mL poly-lysine.The study concludes that,compared with the method of direct adding,the coating of poly-lysine was more effective for reducing the roughness.When coated with 0.1 μg/mL poly-lysine,DNA molecular were better spread on the surface of mica.