Volume 4 Issue 4, April 2009

From possible next-generation electronic devices to the detailed workings of living cells, molecules can process information in many different ways, as Richard Jones reports.

Enzymatic reactions can be coupled together by carefully organizing the enzymes on DNA scaffolds.

Graphene samples with areas of several square centimetres and excellent electrical and optical properties have been fabricated using chemical vapour deposition.

As the removal of excess heat becomes increasingly important in semiconductor devices, localized thermoelectric cooling might be the answer to the problem of hotspots.

A three-dimensional assay based on genetically engineered viral nanoparticles and nickel nanohairs can detect much lower levels of protein markers associated with heart attacks than conventional assays.

Stretching experiments on single molecules offer a unique way to study the fundamental theories of statistical mechanics. Researchers have now shown that entangled calix[4]arene dimers can be used in such experiments as a tuneable model system for investigating the strength of hydrogen bonds on a single-molecule level.

Molecular-scale switches will be central components in nanoscale electronic devices. Switching in single-molecule junctions has so far been achieved through changes in the conformation or charge state of the molecule. Now, reversible binary switching has been demonstrated by mechanical control of the metal–molecule contact geometry—a mechanism which could form the basis for a new class of mechanically activated single-molecule switches.

There is a requirement for site-specific and on-demand cooling in a wide array of electronic, optoelectronic and bioanalytical applications. Thermoelectric coolers, fabricated from nanostructured superlattices based on bismuth and tellurium, have now been integrated into state-of-the-art electronic packages in the first demonstration of a viable chip-scale refrigeration technology.

Indium tin oxide (ITO) is widely used as a transparent conducting coating, but it has been difficult to combine electrical conductivity with good optical properties in the visible region. Researchers have now created layers of ITO nanowires that show optimum electronic and optical properties, and have demonstrated their use as fully transparent top contacts for light-emitting devices.

Structural DNA nanotechnology offers a powerful route to the dynamic and functional control of specific molecular species. Researchers have now demonstrated a dynamic form of patterning wherein a pattern component is captured between two independently programmed DNA devices. A simple and robust error-correction protocol that yields programmed targets in all cases has also been developed.

Predicting and controlling the functions in self-organized biomolecular nanostructures is a major challenge in systems biology. Now researchers have developed DNA scaffolds for the topological organization of different enzymes or cofactor-enzyme pairs. The organization of the biomolecules leads to the activation of enzyme cascades that do not occur in non-organized mixtures, and the reactivity of the system can be controlled by the DNA template.

A mesoporous silicon double layer with different pore sizes functions as a nanoreactor that can isolate, filter and quantify the kinetics of enzyme reactions in real-time by optical reflectivity. This tiny reactor may be used to rapidly characterize a variety of isolated enzymes in a label-free manner.

Early detection of the protein marker troponin I can reduce the risk of death from heart attacks. A three-dimensional assay based on engineered viral nanoparticles and nickel nanohairs is six to seven orders of magnitude more sensitive than conventional assays.

A protein nanopore with a permanent adaptor molecule can continuously identify unlabelled DNA bases with ∼99.8% accuracy. This level of performance could provide the foundation for the development of nanopore-based DNA sequencing technologies that are faster and less expensive than existing approaches.