Effects of hydration on molecular junction transport.

The study of charge transport through increasingly complex small molecules will benefit from a detailed understanding of how contaminants from the environment affect molecular conduction. This should provide a clearer picture of the electronic characteristics of molecules by eliminating interference from adsorbed species. Here we use magnetically assembled microsphere junctions incorporating thiol monolayers to provide insight into changing electron transport characteristics resulting from exposure to air. Using this technique, current-voltage analysis and inelastic electron tunnelling spectroscopy (IETS) demonstrate that the primary interaction affecting molecular conduction is rapid hydration at the gold-sulphur contacts. We use IETS to present evidence for changing mechanisms of charge transport as a result of this interaction. The detrimental effects on molecular conduction discussed here are important for understanding electron transport through gold-thiol molecular junctions once exposed to atmospheric conditions.

Separation and recovery of intact gold-virus complex by agarose electrophoresis and electroelution: application to the purification of cowpea mosaic virus and colloidal gold complex.

Colloidal gold has been coupled to a mutant cowpea mosaic virus (CPMV), which contains 60 cysteine residues on the surface. A purification process was developed to separate the gold-containing viral nanoblocks (VNBs) from the free gold. Agarose electrophoresis was utilized to separate the mixture followed by electroelution of the desired sample to recover the intact virus. Mobility of Au-VNB and free colloidal gold was facilitated by the addition of thioctic acid (TA). 30% of the gold-containing virus was recovered after electroelution as determined by absorbance measurements. Histogram analysis of transmission electron microscopy (TEM) images demonstrated the efficient separation of gold-containing virus from free gold. TEM and scanning electron microscopy (SEM) images indicated that the virus was recovered intact. Monodisperse spherical particles of nominal size of 45 nm were observed under SEM.

Diamond and diamond-like carbon from a preceramic polymer.

The synthesis of poly(hydridocarbyne), one of a class of carbon-based random network polymers and a structural isomer of polyacetlyene, is reported. The network backbone of this polymer is primarily composed of tetrahedrally hybridized carbon atoms, each bearing one hydride substituent and linked via three carbon-carbon single bonds into a three-dimensional random network of fused rings. This atomic-level carbon network backbone confers unusual properties on the polymer, including facile thermal decomposition to form diamond or diamond-like carbon high-quality films at atmospheric pressure, by direct deposition or by chemical vapor deposition (CVD), without the use of hydrogen or any other reagent.