title: High-resolution X-ray photoelectron spectroscopy of mixed silane monolayers for DNA attachment.
abstract: The amine density of 3-aminopropyldimethylethoxysilane (APDMES) films on silica is controlled to determine its effect on DNA probe density and subsequent DNA hybridization. The amine density is tailored by controlling the surface reaction time of (1) APDMES, or (2) n-propyldimethylchlorosilane (PDMCS, which is not amine terminated) and then reacting it with APDMES to form a mixed monolayer. High-resolution X-ray photoelectron spectroscopy (XPS) is used to quantify silane surface coverage of both pure and mixed monolayers on silica; the XPS data demonstrate control of amine density in both pure APDMES and PDMCS/APDMES mixed monolayers. A linear correlation between the atomic concentration of N atoms from the amine and Si atoms from the APDMES in pure APDMES films allows us to calculate the PDMCS/APDMES ratio in the mixed monolayers. Fluorescence from attached DNA probes and from hybridized DNA decreases as the percentage of APDMES in the mixed monolayer is decreased by dilution with PDMCS.
authors.affiliation: Chemistry and Geochemistry Department, Colorado School of Mines, Golden, Colorado 80401, United States.
authors.forename: Rebecca A
authors.initials: RA
authors.lastname: Shircliff
authors.forename: Ina T
authors.initials: IT
authors.lastname: Martin
authors.forename: Joel W
authors.initials: JW
authors.lastname: Pankow
authors.forename: John
authors.initials: J
authors.lastname: Fennell
authors.forename: Paul
authors.initials: P
authors.lastname: Stradins
authors.forename: Maria L
authors.initials: ML
authors.lastname: Ghirardi
authors.forename: Scott W
authors.initials: SW
authors.lastname: Cowley
authors.forename: Howard M
authors.initials: HM
authors.lastname: Branz
mesh_terms: D000588:Amines / Q000737:chemistry; D004247:DNA / Q000737:chemistry*; D015342:DNA Probes / Q000737:chemistry; D005456:Fluorescent Dyes / Q000737:chemistry; D009693:Nucleic Acid Hybridization; D056951:Photoelectron Spectroscopy; D012821:Silanes / Q000737:chemistry*; D012822:Silicon Dioxide / Q000737:chemistry; D013499:Surface Properties
chemical_list: D000588:Amines; D015342:DNA Probes; D005456:Fluorescent Dyes; D012821:Silanes; D012822:Silicon Dioxide; D004247:DNA