全文請?jiān)L問：http://www.spm.com.cn/papers/p68.pdf
Plasmid pBR322 DNA(0.5mg/mL)isolated from Escherichia coli HB101 was suspended in Tris-HCl-EDTA(1mol/L-0.1mol/L,pH8.5);then a drop of the above solution was deposited on freshly clesved mica substrate.After adsorption for about 1 min,the sample was stained with phosphotungstic acid.The residual solution was removed with a piece of filter paper.Afterwards the sample was imaged with a home-made atomic force microscope(AFM)in air.The AFM images of pBR322 DNA with a molecular resolution have been obtained.These images show that pBR322 DNA exists in several different topological structures:(i)relaxed circular DNA with a different diameter;(ii)supercondensed DNA with diffcrent particle sizes;(iii)dimcric catcnane connccted by one relaxed circular molecule and another close-compacted molecule which might be either supercoiled or intramolecular knotted form;(iv)oligomeric catenane with multiple irregular molecules in which DNA is interlocked into a complex oligomer;(v)possibly-existing intermediates formed from monomer to oligomer. 全文請?jiān)L問：http://www.spm.com.cn/papers/p68.pdf 掃描探針顯微鏡(SPM/AFM/STM)