title: Organophosphonate-based PNA-functionalization of silicon nanowires for label-free DNA detection.
abstract: We investigated hydroxyalkylphosphonate monolayers as a novel platform for the biofunctionalization of silicon-based field effect sensor devices. This included a detailed study of the thin film properties of organophosphonate films on Si substrates using several surface analysis techniques, including AFM, ellipsometry, contact angle, X-ray photoelectron spectroscopy (XPS), X-ray reflectivity, and current-voltage characteristics in electrolyte solution. Our results indicate the formation of a dense monolayer on the native silicon oxide that has excellent passivation properties. The monolayer was biofunctionalized with 12 mer peptide nucleic acid (PNA) receptor molecules in a two-step procedure using the heterobifunctional linker, 3-maleimidopropionic-acid-N-hydroxysuccinimidester. Successful surface modification with the probe PNA was verified by XPS and contact angle measurements, and hybridization with DNA was determined by fluorescence measurements. Finally, the PNA functionalization protocol was translated to 2 microm long, 100 nm wide Si nanowire field effect devices, which were successfully used for label-free DNA/PNA hybridization detection.
authors.affiliation: Walter Schottky Institute, Technical University Munich, Munich, Germany.
authors.forename: Anna
authors.initials: A
authors.lastname: Cattani-Scholz
authors.forename: Daniel
authors.initials: D
authors.lastname: Pedone
authors.forename: Manish
authors.initials: M
authors.lastname: Dubey
authors.forename: Stefan
authors.initials: S
authors.lastname: Neppl
authors.forename: Bert
authors.initials: B
authors.lastname: Nickel
authors.forename: Peter
authors.initials: P
authors.lastname: Feulner
authors.forename: Jeffrey
authors.initials: J
authors.lastname: Schwartz
authors.forename: Gerhard
authors.initials: G
authors.lastname: Abstreiter
authors.forename: Marc
authors.initials: M
authors.lastname: Tornow
mesh_terms: D015374:Biosensing Techniques / Q000379:methods*; D003460:Crystallization / Q000379:methods; D004247:DNA / Q000032:analysis* / Q000737:chemistry*; D004563:Electrochemistry / Q000379:methods*; D017403:In Situ Hybridization / Q000379:methods; D046911:Macromolecular Substances / Q000737:chemistry; D008422:Materials Testing; D008968:Molecular Conformation; D049329:Nanostructures / Q000737:chemistry* / Q000648:ultrastructure; D036103:Nanotechnology / Q000379:methods; D010316:Particle Size; D020135:Peptide Nucleic Acids / Q000737:chemistry*; D012825:Silicon / Q000737:chemistry*; D013194:Staining and Labeling / Q000379:methods; D013499:Surface Properties
chemical_list: D046911:Macromolecular Substances; D020135:Peptide Nucleic Acids; D004247:DNA; D012825:Silicon