Directed deposition of single molecules on surfaces

Scanning probe microscopy-based techniques can address and manipulate individual molecules. This makes it possible to use them for building nanostructures by assembling single molecules. Recently the formation of surface structures by positioning single molecules with the Atomic Force Microscope (AFM) was demonstrated on an irreversible delivery process. This inherits the drawback, that the transfer has to occur between differently functionalized surfaces and allows no proofreading of the built structures. Here we demonstrate a procedure for directed deposition of single DNA molecules, which intrinsically allows a reversible positioning. This method uses specific interactions between complementary DNA oligonucleotides for symmetric coupling of the transport molecules to the support and AFM tip, respectively. Thus, it allows for a simple "drag-and-drop" procedure, which relies on the statistical breakage of the molecular interaction under a force load. In addition, the delivery of the transport molecules was observed in real-time by single-molecule fluorescence microscopy.