This paper describes the in‐situ synthesis of an oligo(ethylene glycol)‐functionalized polymer brush in which the oligo(ethylene glycol) chains are presented as side‐chains from a methacrylate backbone that is anchored to the surface. These polymer “bottlebrushes” have been synthesized by surface‐initiated atom transfer radical polymerization (SI‐ATRP) of oligo(ethylene glycol) methyl methacrylate (OEGMA) from a mixed self‐assembled monolayer (SAM) of an ATRP initiator‐functionalized alkanethiol and a diluent, methyl‐terminated thiol. The systematic control of the ATRP initiator surface density afforded by the mixed SAM on gold and the polymerization time enables the polymer chain length and surface density to be independently controlled. Surface plasmon resonance (SPR) spectroscopy of fibronectin (Fn) adsorption on poly(OEGMA) grown from the surface of the mixed SAMs on gold shows that above a threshold solution molar ratio of the ATRP‐initiator thiol to methyl‐terminated thiol of 0.2, and a dry film thickness of ∼ 4 nm, Fn adsorption on the surface‐initiated poly(OEGMA) coatings was below the detection limit of SPR. The relatively low surface density of the ATRP initiator required to confer protein resistance to the surface suggests that SI‐ATRP may be a viable strategy to create protein resistant polymer brushes on real‐world materials.

Atomic force microscopy contact forces are shown to obey a Poisson distribution, so that the ratio of their variance to mean gives the force of a single chemical bond between the tip and sample. The derived single-bond force was able to distinguish nominal van der Waals interactions (60 ( 3 pN) from hydrogenbond interactions (181 ( 35 pN) between atomic force microscope tips and gold and mica surfaces, respectively. This technique greatly reduced sampling time and sample wear, allowed quantitative use of low-resolution force data from a commercially available instrument, and detected important chemical differences between surface functional groups on the samples. These experiments constitute an important step in obtaining chemically specific information in atomic force microscopy.

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We have measured the kinetics of the methane decomposition reaction on Ni(111), Ni(100), and Ni(110) single crystal surfaces under the high incident flux conditions of 1 Torr methane. We find for these processes apparent activation energies of 12.6, 6.4, and 13.3 kcal mol−1, respectively. Initial methane sticking coefficients at 500 K vary with the Ni surface, but are all ∼10−8 to 10−7. The Ni(110) surface is the most active, followed by Ni(100) and Ni(111). A large (∼ factor of 20) kinetic isotope effect is seen for CH4 vs CD4 on the Ni(100) surface, whereas none is seen on the Ni(110) surface. A comparison is made between measured thermal sticking coefficients and those calculated from the results of recent molecular beam experiments of CH4 on Ni(111) and Ni(100) surfaces. Agreement of our results with the Ni(100) beam results is poor, whereas agreement with the Ni(111) beam results is very good. A comparison is also made between our results and rates of the catalytic steam reforming reaction of methane.

A novel technique for the quantitative observation of cell migration along linear gradient substrates functionalized with adhesive proteins is presented. Gradients of the cell adhesion molecule fibronectin are generated by the cross diffusion of functionalizable alkanethiols on gold and characterized by X-ray photoelectron spectroscopy and surface plasmon resonance. Two distinct migration assays are described that characterize the movement of either sparsely populated noncontacting cells or a confluent monolayer of cells into free space. The drift speed of bovine aortic endothelial cells is measured and shown to increase along a fibronectin gradient when compared to a uniform control substrate using both assays. The results of these experiments establish reproducible conditions for studies of cell migration on gradients of surface-bound ligands.

Highly ordered pyrolytic graphite (HOPG) is the substrate often used in scanning tunneling microscope (STM) studies of biomolecules such as DNA. All of the images presented in this article are of freshly cleaved HOPG surfaces upon which no deposition has occurred. These images illustrate features previously thought to be due to biological molecules, such as periodicity and meandering of "molecules" over steps. These features can no longer be used to distinguish real molecules from features of the native substrate. The feasibility of the continued use of HOPG as a substrate for biological STM studies is discussed.

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Oxidation experiments using a particular grade of highly oriented pyrolytic graphite have allowed observation of large numbers of both monolayer and multilayer etch pits on the same samples, formed under identical conditions. Scanning tunneling microscopy was used to measure pits produced after various etch times, temperatures, and O2 pressures. From these data pit growth rates, activation energies, and reaction orders were derived. Although multilayer pits were observed to grow over 3 times faster than monolayer pits in air, both types of pits had the same activation energy. Multilayer etch pits were sometimes observed to form at screw dislocations in the graphite but were also seen in the absence of such defects. The experimentally determined reaction rates and activation energies were not consistent with a direct reaction of edge-carbon atoms with atmospheric oxygen, but instead suggest a chain reaction or preequilibrium process. A mechanism for oxidation of multilayer pits involving reaction of partially oxidized sites on adjacent graphite layers is suggested.