Articles

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.

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.

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.

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.

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.

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.

Carbon nanotubes can enhance the excitability of neurons by forming tight contacts with the cell membranes to favour electrical shortcuts between the distal and proximal compartments of the neuron.

Current methods for synthesizing double-wall carbon nanotubes also produce single- and multi-wall nanotube impurities. Density gradient ultracentrifugation has now been used to separate double-wall nanotubes from such mixtures. The resulting material has distinct advantages over single-wall nanotubes when used in transparent conductors.

A new class of quantum dots with a soft core and a compressive shell has optical and electronic properties that can be tuned by strain.

The growth temperature and diameter of indium arsenide nanowires have been tuned to fabricate highly–reproducible polytypic and twin–plane superlattices within single nanowires. In addition to reducing defect densities, this level of control should also lead to band–gap engineering and novel electronic behaviour.

Combining discrete molecular junctions to make integrated circuits is a major goal in molecular electronics, but problems with reliability, stability and yield have hindered progress. Researchers have now overcome some of these challenges to simultaneously fabricate 20,000 molecular junctions on a single wafer and connect 200 of them in series.

The alarming growth of the antibiotic-resistant superbugs has created a demand for sensors that can investigate antibiotics and their modes of action. The label-free detection of the antibiotic vancomycin binding to mucopeptides on cantilever arrays, with 10 nM sensitivity and at clinically relevant concentrations in blood serum, could lead to improved biosensors and a better understanding of antibiotic drug action in bacteria.

A combination of scanning transmission electron microscopy and electron energy loss spectroscopy has been used to produce and analyse images of free-standing graphene sheets with atomic resolution. The influence of microstructural peculiarities on the stability of the sheets and the evolution and interaction of point defects were also explored.

Nanoparticle superlattices are promising for many applications but the de-wetting processes normally used to produce these systems are not compatible with conventional patterning methods. Researchers have now developed an approach for patterning such superlattices that involves moulding microdroplets containing the nanoparticles and spatially regulating their de-wetting process.

Experiments to explore electron transport in single molecules generally involve the use of chemical linker groups at both ends of the molecule to firmly anchor it to the source and drain contacts. Here it is shown that oligo-phenylene ethynylene molecules with a single anchor group can form molecular junctions as well. The process is attributed to aromatic stacking between neighbouring molecules in nearby electrodes.

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.

Fully exploiting the properties of graphene will require a method for the mass production of this remarkable material. The dispersion and exfoliation of graphite in organic solvents can produce graphene monolayers with a yield of about 1% by weight. Moreover, these samples are free from defects and oxides, and can be used to produce semi-transparent conducting films and conducting composites.

Coating conventional tungsten and stainless steel electrodes with carbon nanotubes improves their performance in research involving the implantation of electrical devices into the nervous system. The results could have an impact on electrophysiology and the development of brain–machine interfaces.

Nanoscale metal/oxide/metal devices that are capable of fast non-volatile switching have been built from platinum and titanium dioxide. The devices could have applications in ultrahigh density memory cells and novel forms of computing.

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.