AVS 53rd International Symposium
    Biomaterial Interfaces Tuesday Sessions
       Session BI-TuP

Paper BI-TuP14
Organophosphonate Functionalized Silicon Nanowires for DNA Hybridization Studies

Tuesday, November 14, 2006, 6:00 pm, Room 3rd Floor Lobby

Session: Biomaterial Interfaces Poster Session
Presenter: D. Pedone, Technical University Munich (TUM), Germany
Authors: D. Pedone, Technical University Munich (TUM), Germany
A. Cattani-Scholz, Technical University Munich (TUM), Germany
M. Dubey, Princeton University
J. Schwartz, Princeton University
G. Abstreiter, Technical University Munich (TUM), Germany
M. Tornow, Technical University Munich (TUM), Germany
Correspondent: Click to Email
Semiconductor nanowire field effect devices have great appeal for label-free sensing applications due to their sensitivity to surface potential changes that may originate from charged adsorbates. In addition to requiring high sensitivity, suitable passivation and functionalization of the semiconductor surface is obligatory. We have fabricated both individual and sets of parallel, eventually freely suspended, silicon nanowires from Silicon-on-Insulator substrates using standard nanopatterning (electron beam lithography, reactive ion etching) and surface micromachining techniques (sacrificial oxide etching). The wires of length 2 µm were typically 100 nm wide and high, and consisted of boron p-type 10@super 18@ cm@super -3@ implantation doped Si. Subsequent to nanofabrication, the devices were bio-functionalized in a 3-step sequence: First, a hydroxyalkylphosphonate monolayer was covalently attached to the native oxide of the Si wire, affording stable and dense passivation in aqueous solutions. Then, bifunctional linker groups were bound to this surface, and in the final step thiol-terminated DNA oligonucleotides were allowed to react with a maleimide moiety of the linker. In initial experiments we investigated DNA hybridization on such functionalized nanowires using a difference resistance setup, where subtracting the reference signal from a second wire could be used to exclude most unspecific effects. A net change in surface potential of the order of -2.5 mV could be detected upon addition of complementary DNA.