Small aromatic organothiol derivatives, with the structure HS±C 6 H 4 ±X, have been used to stabilise gold nanoparticles. The nature of the functional group, X, is important for controlling the relative strength of the particle±particle and particle±solvent interactions and hence in determining the physical properties of these systems (e.g. solubility). Particles were stabilised with different ligands for which X~OH, ±COOH, ±NH 2 , and ±CH 3 and thin ®lms of the particles were formed, by solution evaporation, on microelectrode patterned surfaces. The electronic behaviour indicates that conduction can be understood in terms of an activated electron tunnelling model. Finally, preliminary studies were carried out on the effect of exposure to different chemical vapours on the electronic transport properties.

Attenuated total reflection Fourier transform infrared spectroscopy has been developed to monitor the tethering of phospholipid bilayers to gold-coated, ZnSe crystals. Bilayer attachment has been accomplished by fusing lipid vesicles onto a self-assembled monolayer comprised of a mixture of 2-mercaptoethanol (EO1) and a hexaethyleneoxythiol derivative of cholesterol (EO6C). The cholesteryl moieties penetrate into the lower leaflet of the bilayer and serve to “anchor” the bilayer to the solid support. For fractional surface area coverage of EO6C < 0.24, no lipid adsorption was detected, while for higher EO6C coverages, bilayers are formed with the outer and inner leaflets comprised, respectively, of pure lipid and the complementary lipid/cholesteryl mixture. From a thermodynamic analysis of this result we conclude that the initial step in bilayer self-assembly onto the surface is adsorption and rupture of a single lipid vesicle. The frequencies of the lipid CH2 stretching vibrations are characteristic of a fluid liquid-crystalline bilayer.

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This paper describes the formation of bilayer lipid membranes on a micromachined support, consisting of a 128 µm (diameter) aperture on a gold/SU8 surface suspended over a small aqueous reservoir (∼25 nL). The bilayers are highly impermeable to ion transport with specific resistance values up to 10 7 Ω cm 2 . Single-channel activities of gramicidin and alamethicin were observed in these systems. This work demonstrates that micromachined supports for bilayers are promising for the development of a biosensor with single-channel sensitivity.

In their natural habitat, bacteria are consumed by bacterivorous nematodes; however, they are not simply passive preys. Here we report a defensive mechanism used by certain bacteria to mobilize nematode-trapping fungi to kill nematodes. These bacteria release urea, which triggers a lifestyle switch in the fungus Arthrobotrys oligospora from saprophytic to nematode–predatory form; this predacious form is characterized by formation of specialized cellular structures or ‘traps’. The bacteria significantly promote the elimination of nematodes by A. oligospora. Disruption of genes involved in urea transport and metabolism in A. oligospora abolishes the urea-induced trap formation. Furthermore, the urea metabolite ammonia functions as a signal molecule in the fungus to initiate the lifestyle switch to form trap structures. Our findings highlight the importance of multiple predator–prey interactions in prey defense mechanisms.