MASKING GENERATES CONTIGUOUS SEGMENTS OF METAL-COATED AND BARE DNA FOR SCANNING TUNNELING MICROSCOPE IMAGING

被引:43
作者
DUNLAP, DD
GARCIA, R
SCHABTACH, E
BUSTAMANTE, C
机构
[1] UNIV OREGON,INST MOLEC BIOL,DEPT CHEM,EUGENE,OR 97403
[2] UNIV OREGON,DEPT BIOL,EUGENE,OR 97403
关键词
D O I
10.1073/pnas.90.16.7652
中图分类号
O [数理科学和化学]; P [天文学、地球科学]; Q [生物科学]; N [自然科学总论];
学科分类号
07 ; 0710 ; 09 ;
摘要
To date, no microscopic methods are available to confirm scanning tunneling microscope (STM) images of DNA. The difficulties encountered in repeating these images may be attributed to inadequate distribution of molecules on the substrate, poor adhesion to the substrate, or the low conductivity of the molecules. However, these factors are difficult to assess in an STM experiment where they may act simultaneously. A method to isolate these factors involves partly masking the deposited molecules before coating them with a conductive film to produce adjacent segments of coated and bare DNA after the mask is removed. The coated DNA segments are conductive and mechanically stable to allow easy identification of DNA by the STM. Furthermore, the path of a molecule can be traced from a coated to an uncoated region to test STM imaging of bare DNA. Masked preparations of DNA deposited on platinum/carbon-coated mica and highly oriented pyrolytic graphite were examined with a tunneling current 1000 times lower than the usual nanoamps. The tip apparently displaces molecules adsorbed to graphite to preclude imaging whereas more stably bound DNA on platinum/carbon-coated mica appears in reversed contrast.
引用
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页码:7652 / 7655
页数:4
相关论文
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