Articles in 2009

Individual zinc oxide nanoparticles are shown to be intrinsically ferromagnetic when they are doped with cobalt, which should prove useful in spintronics and other applications.

A class of core–shell nanoparticles self-assembled from amphiphilic peptides can kill a range of bacteria, yeast and fungus. They are more potent than their unassembled peptide counterparts and can suppress bacterial growth in the brains of rabbits infected with meningitis. These particles, which carry a high number of positive charges, are promising antimicrobial agents.

A magnetic vortex can be made to gyrate by a d.c. spin-polarized current. Researchers have now demonstrated the synchronization of four magnetic vortices through their interaction with antivortices. This work could lead to improved nanoscale microwave oscillators and a new way to study the behaviour of interacting solitons.

Mass detection of single biological molecules in real time by a nanoelectromechanical system (NEMS) is demonstrated for the first time, and this is used to perform first generation NEMS-based mass spectrometry. Precipitous frequency shifts, proportional to the mass of the molecules, are recorded in real time by the NEMS mass spectrometry system as protein molecules and nanoparticles adsorb, one-by-one, onto an ultrahigh frequency NEMS resonator.

It has been shown that inhaling multiwalled carbon nanotubes does not lead to significant lung inflammation, but can suppress the immune function of mice. Now it is demonstrated that signals in the lung can activate signals in the spleen to inhibit the immune function of mice inhaling low levels of nanotubes.

DNA nanomachines are synthetic DNA assemblies that switch between defined molecular conformations when stimulated by external triggers. So far, DNA devices have been limited to in vitro applications. A DNA nanomachine has now been constructed that can function as a pH sensor based on fluorescence resonance energy transfer (FRET) inside living cells.

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.