Volume 3 Issue 10, October 2008

When a research council in the UK consulted the public about different aspects of nanomedicine, the feedback was loud and clear. Richard Jones reports.

A Swiss collaboration has found that many more nanoparticles can leave an experimental sewage works than was previously thought.

A catalytic reaction occurring on a single gold nanoparticle can be monitored directly with surface plasmon spectroscopy.

Composites containing ultralong single-walled carbon nanotubes can be integrated with transistors to make stretchable and flexible electronic devices.

The mechanical properties of carbon nanotubes have not matched theoretical predictions in the past. New measurements have now confirmed that nanotubes are indeed as strong as theory suggests.

Ion channels can be attached to certain types of protein receptors in cells to make a detector–switch pair that could be used in various sensing and screening applications.

Nanoscale particles play an important role in the chemical and biological sciences, but efforts to make nanoparticles from borosilicate glass — which exhibits high tolerance to chemicals and solvents — have proved unsuccessful so far. Now it has been shown that upon mixing a silicon–boron binary oxide solution with water, borosilicate nanoparticles are produced as a result of a vigorous exothermic phase separation.

Molecular transport through nanoscale pores is important in many areas of science, but it is difficult to obtain information about the molecules as they pass through the pore. Now it has been shown that imaging with a transmission electron microscope can be used to observe the structure and orientation of a hydrocarbon chain as it passes through a defect in the wall of a carbon nanotube, and also to study how the chain interacts with the nanopore.

Current techniques to determine reaction rates on the nanoscale measure ensemble averages, making it difficult to relate the catalytic activity of nanoparticles to their morphology. Researchers have now used surface plasmon spectroscopy to observe the kinetics of a redox reaction catalysed by a gold nanoparticle and also the atomic deposition of gold onto a nanocrystal.

Single-electron devices offer many advantages over traditional devices, but it is a challenge to fabricate them in large numbers. A novel geometry in which the source and drain electrodes are vertically separated by thin dielectric films, and nanoparticles attached to the sidewall of the dielectric films act as Coulomb islands, can now be used for the CMOS-compatible fabrication of single-electron devices that operate at room temperature.

Semiconducting carbon nanotubes have a direct bandgap, which means that they could form the basis of nanoscale light sources. However, nanotubes tend to emit light over a broad range of wavelengths and directions. Placing the nanotube in a microcavity reduces the spectral width of the output and makes the emission highly directional. This microcavity-controlled, current-driven on-chip emitter is thus an important first step in the development of nanotube-based nanophotonic devices.

Conjugated polymer fibres offer many advantages over other photonic materials, such as tunable properties and easy processability, making them attractive for optoelectronic applications. The waveguiding performance and emission tunability of fully conjugated, electrospun polymer nanofibres have been assessed and their forward emission shown to improve after periodic structures are imprinted using nanoimprint lithography.

The challenge in developing electrical biosensors lies in connecting a molecule detector to an electrical switch. Attaching ion channels to certain cell receptors forms a detector–switch pair that converts chemical information into a measurable electrical signal, creating a platform suitable for screening drugs and other molecules.

The mechanical properties of carbon nanotubes rarely match the values predicted by theory owing to a combination of artefacts introduced during sample preparation and inadequate measurements. However, by avoiding chemical treatments and using high-resolution imaging, it is possible to obtain values of the mean fracture strength that exceed previous values by approximately a factor of three.