Jul 20, 2006
Manipulating DNA molecules
One of the most critical factors when investigating biological molecules with a scanning probe microscope is the method used to adsorb them onto a surface. Molecular details of the specimen will only become apparent when they rise clearly above the flat background.
Several techniques have been developed to tailor the adsorption of biomolecules according to different requirements. These include the functionalization of the surface with self-assembled monolayers, the use of ligand-receptor complexes and the regulation of the buffer conditions.
A research collaboration between Mervyn Miles' group at the University of Bristol, UK, Giovanni Valdrè at the University of Bologna, Italy, and Mark Szczelkun's group in Bristol has investigated how different mineral surfaces influence the deposition of single DNA molecules from solution. In particular, the researchers focused on layered silicates due to their ability to produce atomically flat surfaces when cleaved. Their findings indicated that these surfaces are not inert substrates - as is generally accepted - but can actively drive the deposition of DNA.
In the case of chlorite surfaces the scientists were able to deposit DNA molecules in stretched conformations using only the [m1]variation in surface potential between different areas of the mineral. As can be seen from the image, the degree of manipulation of individual molecules was remarkable. The researchers are confident that the technique will become widespread, particularly when combined with scanning probe microscopy and/or optical tweezers.
About the author
Massimo Antognozzi obtained a PhD in physics in Mervyn Miles' group at the University of Bristol, UK. After a period as a postdoc in the biochemistry department at Bristol studying DNA-enzyme reactions, he moved to the medical school in Hannover, Germany in Bernhard Brenner's Lab. There he investigated molecular motors using optical tweezers. In 2005 he moved back to Bristol in the nanostructures group supported by an RCUK fellowship.