Recent advances in atomic force microscopy of DNA.

Three advances involving DNA in atomic force microscopy (AFM) are reported here. First a HEPES-Mg buffer has been used that improves the spreading of DNA and provides good DNA coverage with as little as 200-500 picograms per sample. Second, the new "tapping" mode has been used to improve the ease and resolution of AFM-imaging of DNA in air. Finally, AFM images are presented of single-stranded phi X-174 virion DNA with the gene 32 single-stranded binding protein. A summary of the current state of the field and of the methods for preparing and imaging DNA in the AFM is also presented.