Spermidine-induced two-dimensional DNA condensations on mica surfaces:A different pathway from condensations in solution  

作　　者：ZHANG XingHua HOU XiMiao JI Chao LIMing DOU ShuoXing WANG PengYe 

机构地区：[1]Laboratory of Soft Matter Physics, Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China

出　　处：《Chinese Science Bulletin》2009年第14期2425-2433,共9页

基　　金：Supported by the National Natural Science Foundation of China (Grant Nos. 10834014, 10674173);National Basic Research Program of China (Grant No. 2009CB930704)

摘　　要：With atomic force microscopy (AFM) we systematically studied the DNA condensations on mica surfaces induced by multivalent cation spermidine. The pattern of the DNA condensates is a flat single layer, with a core in the centre and DNA wrapping around it at high density. We assume this to be a two-dimensional condensation of free coiled DNA onto negatively charged mica surfaces by the multivalent cation. The DNA molecules condense on mica surfaces via a pathway different from the formation of toroids, rods or globules in bulk solutions. We give an explanation to why toroid structures are difficult to be observed by AFM, and further discuss the relationship between DNA condensations in solutions and on mica surfaces. The present work will be helpful for understanding the behaviors of DNA on charged surfaces, which might be significantly different from that in solutions.With atomic force microscopy （AFM） we systematically studied the DNA condensations on mica surfaces induced by multivalent cation spermidine. The pattern of the DNA condensates is a flat single layer, with a core in the centre and DNA wrapping around it at high density. We assume this to be a two-dimensional condensation of free coiled DNA onto negatively charged mica surfaces by the multivalent cation. The DNA molecules condense on mica surfaces via a pathway different from the formation of toroids, rods or globules in bulk solutions. We give an explanation to why toroid structures are difficult to be observed by AFM, and further discuss the relationship between DNA condensations in solutions and on mica surfaces. The present work will be helpful for understanding the behaviors of DNA on charged surfaces, which might be significantly different from that in solutions.

关 键 词：DNA分子 表面 云母 诱导 亚精胺 原子力显微镜 多价阳离子 溶液 

分 类 号：O484[理学—固体物理] Q523[理学—物理]