Volume 4 Issue 3, March 2009

New research by social scientists is presenting a clearer picture of the factors that influence the public perception of nanotechnology and, as Chris Toumey reports, the results present challenges for those working to increase public acceptance of nanoscience and technology. See focus on public perceptions of nanotechnology.

Information can be encoded in electron waves on a surface using electronic holograms constructed from single molecules. The information is stored in two spatial dimensions and one energy dimension, and is read with a scanning tunnelling microscope.

Semiconducting inks based on carbon nanotubes have mobilities that are comparable with those of polycrystalline silicon, and could one day match the performance of single-crystal silicon. A host of applications based on this inexpensive approach to electronics are expected.

Current diagnostic tools detect cartilage degeneration only at advanced stages, but the atomic force microscope can now detect structural changes earlier, paving the way for treatment of joint diseases.

It is possible to couple the spins of molecular nanomagnets — each acting as a quantum bit — to make an entangled state that could prove useful in a quantum computer.

The observation of a Mott transition from a metal to an insulator in an ultraclean carbon nanotube could open the door to a new generation of experiments that explore the influence of electron correlations on the properties of condensed-matter systems.

The interplay between atomic and electronic structure, in association with applied mechanical stress, can lead to surprising differences between the atomic arrangements found in nanoscale and macroscopic structures. The spontaneous formation of the smallest possible metal nanotube with a square cross-section has now been observed during the elongation of silver nanocontacts.

Knowledge about strain at the nanoscale is essential for tailoring the mechanical and electronic properties of materials. It has now been shown that infrared near-field microscopy can provide direct, non-invasive mapping of residual strain fields, with nanoscale resolution. In addition, plasmon-assisted near-field imaging of free-carrier properties in nanoscale strain fields has been demonstrated.

A voltage-induced symmetry change in a ferromagnetic material can change its magnetization or magnetic anisotropy, but these effects are too weak to be used in memory devices. Researchers have now shown that a relatively small electric field can cause a large change in the magnetic anisotropy of a few atomic layers of iron. The results could lead to low-power logic devices and non-volatile memory cells.

A ‘smart dust’ biosensor — composed of tiny particles that can move, sense and process signals — can capture, tag and transport analytes to a detection region. Built from antibody-functionalized microtubules and kinesin motors powered by caged ATP molecules, this small and autonomous sensor could have many applications in biomedicine and biodefence.

Information has been encoded into the quantum wavefunctions of a two-dimensional electron gas using electronic holograms constructed from single molecules. The information is stored in two spatial dimensions and one energy dimension and is read with a scanning tunnelling microscope, to enable information densities exceeding 20 bits nm⁻².

The ability to assemble weakly-interacting subsystems is a prerequisite for implementing quantum-information processing. In recent years, molecular nanomagnets have been proposed as suitable candidates for qubit encoding and manipulation, with antiferromagnetic Cr₇Ni rings of particular interest. It has now been shown that such rings can be chemically linked to each other and the coupling between their spins tuned through the choice of chemical linker.

Membrane proteins are central to many biological processes, but it is difficult to measure their interactions with other objects. Sensors based on arrays of resonating microcantilevers have now performed label-free and time-resolved measurements of the interactions between a protein receptor and a bacterial virus under physiological conditions.

Atomic force microscopy can be used to detect the early onset of osteoarthritis in cartilage samples obtained from mice and patients, well before conventional diagnosis methods. This work could lead to a minimally invasive tool for the early detection of osteoarthritis and the development of more effective therapies for treating this disease.

Nanocrystals - such as quantum dots and magnetic nanoparticles - embedded in lipoproteins can be used to image and quantify the kinetics of lipid metabolism in vivo in a non-invasive manner using fluorescence and dynamic magnetic resonance imaging.