title: Bioreactive self-assembled monolayers on hydrogen-passivated Si(111) as a new class of atomically flat substrates for biological scanning probe microscopy.
abstract: This is the first report of bioreactive self-assembled monolayers, covalently bound to atomically flat silicon surfaces and capable of binding biomolecules for investigation by scanning probe microscopy and other surface-related assays and sensing devices. These monolayers are stable under a wide range of conditions and allow tailor-made functionalization for many purposes. We describe the substrate preparation and present an STM and SFM characterization, partly performed with multiwalled carbon nanotubes as tapping-mode supertips. Furthermore, we present two strategies of introducing in situ reactive headgroup functionalities. One method entails a free radical chlorosulfonation process with subsequent sulfonamide formation. A second method employs singlet carbenemediated hydrogen-carbon insertion of a heterobifunctional, amino-reactive trifluoromethyl-diazirinyl crosslinker. We believe that this new substrate is advantageous to others, because it (i) is atomically flat over large areas and can be prepared in a few hours with standard equipment, (ii) is stable under most conditions, (iii) can be modified to adjust a certain degree of reactivity and hydrophobicity, which allows physical adsorption or covalent crosslinking of the biological specimen, (iv) builds the bridge between semiconductor microfabrication and organic/biological molecular systems, and (v) is accessible to nanopatterning and applications requiring conductive substrates.
authors.affiliation: Department of Biochemistry, Stanford University Medical Center, California 94305-5307, USA. pwagner@stanford.edu
authors.forename: P
authors.initials: P
authors.lastname: Wagner
authors.forename: S
authors.initials: S
authors.lastname: Nock
authors.forename: J A
authors.initials: JA
authors.lastname: Spudich
authors.forename: W D
authors.initials: WD
authors.lastname: Volkmuth
authors.forename: S
authors.initials: S
authors.lastname: Chu
authors.forename: R L
authors.initials: RL
authors.lastname: Cicero
authors.forename: C P
authors.initials: CP
authors.lastname: Wade
authors.forename: M R
authors.initials: MR
authors.lastname: Linford
authors.forename: C E
authors.initials: CE
authors.lastname: Chidsey
mesh_terms: D000473:Alkanes / Q000737:chemistry; D003432:Cross-Linking Reagents; D004247:DNA / Q000648:ultrastructure; D006859:Hydrogen; D016252:Microscopy, Scanning Tunneling / Q000379:methods*; D015394:Molecular Structure; D012825:Silicon / Q000737:chemistry*; D013057:Spectrum Analysis; D013388:Succinimides / Q000737:chemistry; D013449:Sulfonamides / Q000737:chemistry; D013499:Surface Properties
chemical_list: D000473:Alkanes; D003432:Cross-Linking Reagents; D013388:Succinimides; D013449:Sulfonamides; D006859:Hydrogen; D004247:DNA; D012825:Silicon