Imaging of DNA Molecules by Atomic Force Microscope

This paper explores suitable conditions for the imaging of DNA molecules by atomic force microscope (AFM). 
As a typical biological macro-molecule, DNA with genetic information has  attracted  extensive attention,  which is an 
important research  subject in biomedicine.  In this work, 3-Aminopropyl Triethyl Silane (APTES), Ni2+and  Mg2+
were used to modify the  surface of  mica substrate, and DNA molecules were adhered to the mica surface through the 
physical interaction of charges. The DNA molecules were imaged  using an AFM under both air conditions and liquid 
conditions. By analyzing the images of DNA molecules obtained in the experiments, it was found that the mica surface modified with Ni2+had the best imaging quality under the liquid condition. This work will be useful for the study of high quality AFM imaging of DNA molecules, and the manipulation of DNA molecules by AFM mechanical forces.