Volume 3 Issue 6, June 2008

Scientists often invoke comparisons with nature when discussing developments in nanotechnology, but the relationship between the two is more complex than it first appears, and can be broken down into nine different narratives.

Self-assembled nanofibres have been used to promote the growth of neuronal cells in mice after spinal cord injuries.

In the past, nanoelectromechanical resonators have been passive devices that required external oscillators to keep them working, so the development of a self-sustaining resonator powered only by a d.c. voltage is a major advance.

Membranes made of manganese oxide nanowires can be used to selectively absorb oil from water through a combination of superhydrophobicity and capillary action.

Rising production and use of engineered nanomaterials increases the likelihood of environmental exposure. A preliminary modelling study shows that quantitative risk assessment is possible but a large knowledge gap still exists.

The patterning of self-assembled monolayers can be controlled on subnanometre length scales by careful design of the molecular components.

Nanocomposites reinforced with functionalized graphene sheets that form strong interactions with the surrounding polymer matrix are shown to have significantly enhanced thermal and mechanical properties.

Through a combination of superhydrophobicity and capillary action, membranes made of manganese oxide nanowires can be used to selectively absorb hydrophobic contaminants, such as oil, from water.

Researchers have measured the mechanical response of individual metallofullerene molecules confined inside a carbon nanotube to the tip of an atomic force microscope with atomic resolution. Highly elastic — that is, almost frictionless — behaviour was observed under certain conditions

To date most sensors based on nanoelectromechanical systems (NEMS) have been passive devices that require external periodic or pulsed stimuli to excite them into resonance. Now researchers have demonstrated an active NEMS device excited by a d.c. source that exhibits excellent frequency stability, linewidth narrowing and low-noise performance.

Nanoparticles released into the environment could impact the performance of the protozoa that regulate the population of bacteria and other microbes in water. New experiments show that carbon nanotubes are internalized by one such protozoa, Tetrahymena thermophila, reducing its ability to ingest and digest harmful bacteria species.

New laboratory studies using a simplified food web show that quantum dots can be ingested by certain ciliates and transferred to higher trophic organisms such as the predatory rotifers by dietary uptake.

A small organic molecule self-assembles into helical ribbons that wrap around single-walled carbon nanotubes. The strength of the wrapping interaction depends on the chirality of each nanotube and enables mixtures to be separated.

Computer simulations suggest that high concentrations of fullerenes can change the mechanical properties of the lipid membrane in cells. However, these changes are not large enough to damage the membrane, which suggests that other mechanisms are responsible for membrane disruption and fullerene toxicity.