3 research outputs found
Data and algorithms
Data and algorithms for analysis associated with manuscript. See 'readme.txt' for further detail
A Selective Blocking Method To Control the Overgrowth of Pt on Au Nanorods
A method
for the preparation of smooth deposits of Pt on Au nanorods
is described, involving sequential deposition steps with selective
blocking of surface sites that reduces Pt-on-Pt deposition. The Au–Pt
nanorods prepared by this method have higher long-term stability than
those prepared by standard Pt deposition. Electrochemical data show
that the resulting structure has more extended regions of Pt surface
and enhanced activity toward the carbon monoxide oxidation and oxygen
reduction reactions
Angle-Resolved XPS Analysis and Characterization of Monolayer and Multilayer Silane Films for DNA Coupling to Silica
We measure silane density and Sulfo-EMCS
cross-linker coupling
efficiency on aminosilane films by high-resolution X-ray photoelectron
spectroscopy (XPS) and atomic force microscopy (AFM) measurements.
We then characterize DNA immobilization and hybridization on these
films by <sup>32</sup>P-radiometry. We find that the silane film structure
controls the efficiency of the subsequent steps toward DNA hybridization.
A self-limited silane monolayer produced from 3-aminopropyldimethylethoxysilane
(APDMES) provides a silane surface density of ∼3 nm<sup>–2</sup>. Thin (1 h deposition) and thick (19 h deposition) multilayer films
are generated from 3-aminopropyltriethoxysilane (APTES), resulting
in surfaces with increased roughness compared to the APDMES monolayer.
Increased silane surface density is estimated for the 19 h APTES film,
due to a ∼32% increase in surface area compared to the APDMES
monolayer. High cross-linker coupling efficiencies are measured for
all three silane films. DNA immobilization densities are similar for
the APDMES monolayer and 1 h APTES. However, the DNA immobilization
density is double for the 19 h APTES, suggesting that increased surface
area allows for a higher probe attachment. The APDMES monolayer has
the lowest DNA target density and hybridization efficiency. This is
attributed to the steric hindrance as the random packing limit is
approached for DNA double helices (dsDNA, diameter ≥ 2 nm)
on a plane. The heterogeneity and roughness of the APTES films reduce
this steric hindrance and allow for tighter packing of DNA double
helices, resulting in higher hybridization densities and efficiencies.
The low steric hindrance of the thin, one to two layer APTES film
provides the highest hybridization efficiency of nearly 88%, with
0.21 dsDNA/nm<sup>2</sup>. The XPS data also reveal water on the cross-linker-treated
surface that is implicated in device aging