In vitro assembly of a viral envelope.

Viruses such as influenza and Ebola are enveloped in lipid bilayers annexed from host cells and containing glycoproteins essential for the infection process. At the molecular level little is known about the assembly process in terms of physical interactions between the lipids and glycoproteins. In this paper we assemble HIV glycoproteins in lipid vesicles in order to examine envelope assembly, a process that is usually only executed under control of a host cell. Using atomic force microscopy it was possible to observe fusion of individual envelope like particles, and contrast this with the behaviour of lipid vesicles without envelope glycoproteins. It was found that the inclusion of glycoproteins caused the vesicles to distort and that the subsequent fusion "footprint" with a lipid bilayer was related to the envelopes' unique morphology. This non-spherical morphology suggests that the presence of a viral capsid may be essential for the stability of an enveloped virus. Interactions between trans-membrane gp41 and gp120, the spikes protruding from a virion, were examined using supported lipid bilayers. Interactions between the gp120 and membrane-located gp41 resulted in the assembly of unusual molecular wires, one molecule in height and with a zigzag arrangement of gp120 molecules. In this work we have shown that purely physical/chemical interactions have dramatic effects on glycoprotein/lipid assembly and should be considered in the development of virus based technologies such as virosomes.

Oscillatory carbonylation using alkyne-functionalised poly(ethylene glycol).

In this study palladium-catalysed oscillatory carbonylation has been achieved using mono alkyne-terminated poly(ethylene glycol) methyl ether substrates. Reproducible, synchronised oscillations in pH and solution turbidity have been recorded over several days. A reaction network accounting for the observed phenomena has been proposed.

Creating a bio-hybrid signal transduction pathway: opening a new channel of communication between cells and machines.

Manipulation of signal transduction pathways presents a viable mechanism to interface cells with electronics. In this work, we present a two-step signal transduction pathway involving cellular and electronic transduction elements. In order to circumvent many of the conventional difficulties encountered when harnessing chemical signalling for the purpose of electronics communication, gaseous nitric oxide (NO) was selected as the signalling molecule. By genetic engineering of the nitric oxide synthase protein eNOS and insertion of light-oxygen-voltage (LOV) domains, we have created a photoactive version of the protein. The novel chimeric eNOS was found to be capable of producing NO in response to excitation by visible light. By coupling these mutant cells to a surface modified platinum electrode, it was possible to convert an optical signal into a chemical one, followed by subsequent conversion of the chemical signal into an electrical output.

Protein directed assembly of lipids.

Highly ordered ring-like structures are formed via the directed assembly of lipid domains in supported bilayers, using the extracellular matrix protein fibronectin. The ability of biological molecules to guide nanoscale assembly suggests potential biomimetic approaches to nanoscale structures.