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2006 Highlights

Patterning of Large Arrays of Organic Semiconductor Single Crystals

Field-effect transistors made of single organic crystals are ideal for studying the charge transport characteristics of organic semiconductor materials. Their outstanding device performance, relative to that of transistors made of organic thin films, makes them also attractive candidates for electronic applications such as active matrix displays and sensor arrays. The only approach currently available […]

Chemical Imaging of Lipid Domains by High-Resolution Secondary Ion Mass Spectrometry (HR-SIMS)


Marjorie Longo, UC Davis; Steve Boxer, Stanford University

Phase separated supported lipid bilayers were chemically imaged by HR-SIMS performed with the NanoSIMS 50 (Cameca Instruments). A focused Cs+ ion beam is rastered across the sample, extensively fragmenting the surface components. Secondary ions of up to 5 different masses are simultaneously detected and a lateral resolution of 50 nm can be achieved. In our experiments, a unique stable isotope was selectively incorporated into each membrane component, and the intensity and location of the isotopically enriched secondary ions were used to create a component-specific image of the phase separated lipid bilayer.

Simulations of Polyphenylacetylene (PPA) “Foldamers”

Vijay Pande, Stanford University.

What are PPA “foldamers”

nonbiological polymers that fold
model systems for self-assembling nano structures
challenge for simulation: long timescale and complex dynamics

New results

longer chains considerably are more complex: multiple traps and remarkable complexity
new methods used to predicted long timescale behavior: Markovian model and Folding@Home grid computing
Folding@Home: a new paradigm […]

The Key to Making High Mobility Polymer Thin Film Transistors: Nucleation of Crystals Off of the Gate Dielectric

Polymer Thin Films When conjugated polymer crystals nucleate off of the gate dielectric, the conjugated backbones, shown in red, are all aligned. Charge can easily hop from one grain to another.

Kline, R. J., McGehee, M. D., Fréchet, J. M. J., et al. Macromolecules 38, 3312 (2005)
Kline, R. J., McGehee, M. D. & Toney, M. F., Nature Materials 5, 222 (2006).

Label-Free Bioanalytical Detection Using Membrane-Coated Silica Nanoparticles

Label-Free Bioanalytical Detection.jpg

Membrane-coated silica particles exhibit colloidal phase transitions that are governed by membrane surface interactions.

Collective phase behavior of the beads serves as a cooperative amplifier; a readily detectable response from small numbers of microscopic binding events between ligands and membrane-bound protein(s) of interest alters the structure of the colloidal dispersion in measurable ways.

Further statistical analysis of bead pair distribution functions enables quantitative determination of binding affinities.