Volume 9 Issue 11, November 2010

Twenty-five years on from the discovery of C₆₀, the outstanding properties and potential applications of the synthetic carbon allotropes — fullerenes, nanotubes and graphene — overwhelmingly illustrate their unique scientific and technological importance.

A green use of carbon-based resources that minimizes the environmental impact of carbon fuels could allow a smooth transition from fossil fuels to a sustainable energy economy.

Jim Heath tells Nature Materials about the discovery of C₆₀ and how the findings catalysed our way of thinking about size and shape on the nanoscale.

Biocompatible light-emitting structures based on high-performance inorganic compound semiconductors on flexible substrates open the path to futuristic therapeutic devices, instrumented surgical gloves and many other applications.

Experiments on magnetic insulators and semiconductors imply that the spin Seebeck effect is conceptually different from the standard thermoelectric effect, launching new challenges for both theorists and experimentalists in spintronics.

Propelled by the recent renaissance of oxides, a material has emerged with sufficient purity and perfection to join those select materials that show the fractional quantum Hall effect: ZnO.

Excitons in a highly ordered organic semiconductor are found to diffuse over distances of a few micrometres. This may pave the way towards designing efficient excitonic solar cells.

The DNA-mediated assembly of anisotropic gold nanoparticles shows the importance of particle shape in the controlled formation of DNA–nanoparticle superlattices.

The fabrication of oxide thin-film heterostructures has improved considerably over the past few years. The first demonstration of the fractional quantum Hall effect in an oxide now attests to the potential of these compounds to rival conventional semiconductors.

By using the spin Seebeck effect, the generation of an electric voltage from a heat gradient is demonstrated for the first time in an insulator. This finding extends the range of potential materials for thermoelectric applications, and provides a crucial piece of information for understanding the physics of the spin Seebeck effect.

The generation of an electric voltage from a heat gradient is demonstrated for the first time in the ferromagnetic semiconductor GaMnAs. This allows flexible design of the magnetization directions, a large spin polarization, and measurements across the magnetic phase transition. The effect is observed even in the absence of longitudinal charge transport.

The improvement of catalysts for the oxygen-reduction reaction is an important challenge for fuel cells and other electrochemical-energy technologies. A composite nanoporous Ni–Pt alloy with a tailored geometric architecture is now shown to exhibit high mass activity for oxygen reduction.

Bilayer membranes encase several biological entities, for example cells and organelles. Their rupture under mechanical stress usually occurs by a pore-formation mechanism. Now, lipid-bilayer membranes spreading on a solid surface are shown to rupture in a series of rapid avalanches causing fractal membrane fragmentation.

DNA-functionalized, anisotropic nanostructures, such as triangular nanoprisms and nanorods, are shown to assemble by means of DNA hybridization into colloidal crystal structures. The crystallization parameters of these nanostructures, and hence the dimensionality and symmetry of the resultant superlattice, are strongly influenced by particle shape.

The formation of a NaTl lattice structure by DNA-mediated assembly of gold nanoparticles and virus-like protein nanoparticles is reported. The inorganic and organic components each form diamond-like frameworks that interpenetrate to give the NaTl lattice. These diamond-like structures are of interest for potential applications as photonic materials.

The oral delivery of small interfering RNA (siRNA) to diseased intestinal tissue is challenging because of the harsh environment created by gastrointestinal fluids and mucosa. Now, such delivery of siRNA to sites of intestinal inflammation is achieved using polythioketal nanoparticles and gene expression is successfully inhibited in the inflamed tissue.

Flexible electronic devices that can be stretched without losing performance have seen increasing functionality. In particular, the demonstration of light-emitting diodes and photodetectors on flexible electronic substrates now opens the door to applications of flexible optoelectronic sheets in biomedicine and robotics.

Excitons in polycrystalline films of organic semiconductors typically migrate distances of the order of tens of nanometres. Photoconductivity measurements in highly ordered rubrene now show that exciton diffusion can reach the micrometre range, opening a route to designing excitonic circuitry for applications in photocatalysis, photochemical sensing or photovoltaic energy conversion.

In situ spectroscopic analysis of operating solid oxide electrochemical cells has proved to be difficult owing to high-vacuum requirements. Ambient-pressure X-ray photoelectron spectroscopy on single-chamber cells now suggests that surface reaction kinetics and electron transport on the electrodes are co-limiting processes.

The discovery of C60 — a molecular allotrope of carbon — marked a pivotal moment in the field of nanotechnology. Twenty-five years on, carbon remains the element of choice for simple but functional materials.