Drawing with DNA

Nanotechnology

A common problem encountered when different materials are to be deposited on the same spot is that they dont land exactly on top of each other. The result is multiple imprints slightly misaligned—what is called lack of registry.

A tool has now been developed to address the problem for nanoscale applications: a double-barreled nanopipette that gives researchers fine control when depositing molecules on a surface. David Klenerman of the University of Cambridge and his coworkers there and at Imperial College London use the nanopipette with scanning ion conductance microscopy to draw pictures on glass slides with fluorescent DNA as the pigment (Angew. Chem. Int. Ed. 2005, 44, 6854).

Each barrel of the nanopipette is filled with an electrolyte solution containing one of the components to be deposited. As the nanopipette approaches the surface, a droplet forms at the tip. A voltage applied between the two barrels determines which component and how much will be deposited. A variety of biological and synthetic molecules can be deposited.

As a demonstration of the fine control and improved registry, Klenermans team used red and green DNA, produced by fluorescence labeling, to reproduce artwork. Spots containing only one fluorophore show up as that color, whereas spots containing both fluorophores show up as yellow.

Each image took about 30 minutes to generate. We see it as a prototyping tool, Klenerman says. He plans to combine this technique with a method for imaging live cells. We can imagine controllably dosing a receptor on a cell surface and seeing how much is required to make it respond, he says.