Nanomagnetic remote control of animal behaviour

MAGNETIC nanoparticles targeted to nerve cell membranes can be used to remotely control cellular activity and even the simple reflex behaviours of nematode worms, according to research by a team of biophysicists at the University of Buffalo. The new method, which is described in the journal Nature Nanotechnology, could be very useful for investigating how cells interact in neuronal networks, and may eventually lead to new therapies for cancer and diabetes.

Heng Huang and her colleagues synthesized manganese-iron nanoparticles, each just 6 millionths of a millimeter in diameter, and coated with the bacterial protein straptavidin attached to a fluorescent molecule called DyLight549. Strepdavidin binds another molecule, much like a key fits into a lock, enabling specified cells to be targeted, while DyLight549 acts like a molecular thermometer, whose fluoresence intensity changes with temperature.

Silver nanorod microscopy

Japanese researchers have developed a design concept for a light microscope which could in principle be used for imaging of nanoscale objects. The device would rely on a novel subwavelength imaging technique which allows for the visualization of objects that are smaller than the wavelength of the photons used in the device.

Once thought to be impossible, subwavelength imaging can now be performed because of the development of nanostructured metamaterials with a negative refractive index, which can act as a lens by focusing incident light. Until now though, such materials only worked at one wavelength and could only transfer images over short distances, so their potential for use as lenses was limited.

Reporting in a recent issue of Nature Photonics, Satoshi Kawata of the RIKEN Nanophotonics Laboratory and his colleagues propose a lens consisting of stacked silver nanorods, which would be capable not only of colour imaging at a resolution of nanometers using visible light waves, but also of transferring the images over much longer distances. Such a device could be used to directly image viruses or the distribution of protein molecules within cell membranes.