Imaging and Force Spectroscopy on DNA : Amplitude and Frequency Modulation on Single DNA Molecules

✍ Scribed by Giovanni Di Santo; Susana Tobenas; Jozef Adamcik; Giovanni Dietler

• Book ID: 102866641
• Publisher: Wiley (John Wiley & Sons)
• Year: 2008
• Weight: 729 KB
• Volume: 10
• Category: Article
• ISSN: 1439-4243
• DOI: 10.1002/imic.200890071

✦ Synopsis

Imaging of single DNA molecules has reached the best spatial resolution by means of dynamic force mode. Amplitude and Frequency Modulation modes at room and low temperature in UHV indicate semi-contact or non-contact as the best modes to achieve high resolution on such small biological molecules. A step forward to more quantitative results is single point force spectroscopy. The force and potential evaluation from the experimental curves evidences the contrast between substrate and DNA and suggests the Non Contact AFM as a possible tool for molecular recognition. Fig.: 1 Topographic AFM images by Amplitude Modulation in ambient conditions (left), UHV at room (center) and LN 2 temperatures (right). The DNA molecules are deposited on freshly cleaved mica from a 5 mM MgCl 2 solution. The height multiprofile plot show the 0.6-0.7 nm value for the molecule height as measured in air. Profile plots for the UHV results shows an increased measured height (1.0±0.1 nm) in good agreement with similar measurements reported in the literature [12].