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Nanoparticles offer hope for frayed nerves
Technology 3+ to a 4+ state, but reverts back over time, which means that a small dose of nanoparticles can keep working for weeks at a time. “If you can confine it to the site of injury,” says Hickman, “you should be able to have a longlasting neuroprotective effect.” Schubert adds that the
Nanoparticles offer hope for frayed nerves
Do away with wires for more robust sensors
WHETHER they are detecting toxic molecules in the air or pathogenic bacteria in a vat of yoghurt, many microscopic sensors share a crucial weakness: the ultra-thin wires that relay signals from the physical sensing components to the circuitry. 26 | NewScientist | 27 January 2007
070127_N_TechLast.indd 26
nanoparticles seem to be taken up into nerve cells at the synapses, the junctions across which cells communicate with one another. This may give cerium oxide particles an advantage over other, more powerful, antioxidants that do not enter neurons in this way. “In general, the antioxidant approach is a good one, and this –Free radicals are already doing their worst– is an elegant way of doing that,” says Ravi Bellamkonda of the Laboratory for Neuroengineering 5 nanometres in diameter, on oxidative damage (Biochemical in Atlanta, Georgia, which is cultures grown from neurons and Biophysical Research run jointly by the Georgia taken from the spinal cords of Communications, vol 342, p 86). Institute of Technology and adult rats. The particles were able The researchers also found that Emory University. the particles themselves were not to protect the spinal neurons However, Bellamkonda warns from hydrogen peroxide, a toxic to the cells. that the work is still at an early powerful oxidising agent Now James Hickman and his stage. The next test will be in (Biomaterials, DOI: 10.1016/ colleagues at the University of demonstrating that the j.biomaterials.2006.11.036). Central Florida in Orlando have nanoparticles show similar The researchers found that in shown the nanoparticles can also neuroprotective benefits in live exerting its antioxidant effect, protect spinal neurons. They animals. Peter Aldhous ● cerium is itself oxidised from a tested similar particles, less then
PAULA BRONSTEIN/GETTY
NANOPARTICLES have had a bad rap lately over fears about their toxicity. Now, though, it seems the particles also have a kinder side. Cerium oxide nanoparticles have been shown to protect nerve cells from damage and so might one day be used to treat patients with spinal injuries or stroke. When the spinal cord is damaged, or part of the brain is starved of oxygen, the initial injury soon escalates and neighbouring cells begin to die. Many fall victim to oxidative damage from free radicals, which are released as the immune system goes into inflammatory overdrive to clear up the mess. Last year, a team led by neurobiologist David Schubert of the Salk Institute for Biological Studies in La Jolla, California, showed that cerium oxide nanoparticles can protect cultures of mouse brain cells from
“The particles were able to protect the neurons from a powerful oxidising agent”
If those fragile wires break or corrode, the sensor becomes useless. Now a wireless sensor has been developed that detects substances through their effect on an applied magnetic field. “This is a wireless technology you can embed in any environment where sub-millimetre wiring is a risk, either due to spark risk or because of its fragility,” says the sensor’s developer, Mike Gibbs, an expert in engineering materials at the University of Sheffield in the UK. Typical molecular sensors, for example, use 1-micrometre-long silicon cantilevers that ping up and down like a diving board when the target molecule lands on them. This vibrates a piezoelectric crystal, producing a fluctuating current of
the same frequency. Wires connecting the crystal to a sensing circuit allow the device to register the cantilever’s motion. To build his wireless sensor, Gibbs applied a 100-nanometre-thick magnetic film to a silicon nitride cantilever. “Pinging” the cantilever with a field from an external electromagnetic coil sets it vibrating. That vibration in turn induces a current in the coil at the same frequency. When a molecule or pathogen of interest lands on the cantilever it will alter this frequency
“The absence of exposed electrical connections could be very useful”
by a telltale amount. Because there are no wires to the cantilever, it can be placed in a spark-free environment, with the coil at a safe remove. Gibbs has filed a patent on the idea, which he presented at an Institute of Nanotechnology conference in London last week. The absence of exposed electrical connections could be very useful in some applications, says Ian Eastwood of Authentix, a security technology firm based in Dunnington, UK. “Airlines have asked us to look into ways of sensing contaminated aviation fuel to prevent the equivalent of someone putting sugar in a car’s fuel tank. Removing spark risk could be one way we could do this.” Paul Marks ● www.newscientist.com
22/1/07 3:07:52 pm
Nanoparticles offer hope for frayed nerves
Do away with wires for more robust sensors
WHETHER they are detecting toxic molecules in the air or pathogenic bacteria in a vat of yoghurt, many microscopic sensors share a crucial weakness: the ultra-thin wires that relay signals from the physical sensing components to the circuitry. 26 | NewScientist | 27 January 2007
070127_N_TechLast.indd 26
nanoparticles seem to be taken up into nerve cells at the synapses, the junctions across which cells communicate with one another. This may give cerium oxide particles an advantage over other, more powerful, antioxidants that do not enter neurons in this way. “In general, the antioxidant approach is a good one, and this –Free radicals are already doing their worst– is an elegant way of doing that,” says Ravi Bellamkonda of the Laboratory for Neuroengineering 5 nanometres in diameter, on oxidative damage (Biochemical in Atlanta, Georgia, which is cultures grown from neurons and Biophysical Research run jointly by the Georgia taken from the spinal cords of Communications, vol 342, p 86). Institute of Technology and adult rats. The particles were able The researchers also found that Emory University. the particles themselves were not to protect the spinal neurons However, Bellamkonda warns from hydrogen peroxide, a toxic to the cells. that the work is still at an early powerful oxidising agent Now James Hickman and his stage. The next test will be in (Biomaterials, DOI: 10.1016/ colleagues at the University of demonstrating that the j.biomaterials.2006.11.036). Central Florida in Orlando have nanoparticles show similar The researchers found that in shown the nanoparticles can also neuroprotective benefits in live exerting its antioxidant effect, protect spinal neurons. They animals. Peter Aldhous ● cerium is itself oxidised from a tested similar particles, less then
PAULA BRONSTEIN/GETTY
NANOPARTICLES have had a bad rap lately over fears about their toxicity. Now, though, it seems the particles also have a kinder side. Cerium oxide nanoparticles have been shown to protect nerve cells from damage and so might one day be used to treat patients with spinal injuries or stroke. When the spinal cord is damaged, or part of the brain is starved of oxygen, the initial injury soon escalates and neighbouring cells begin to die. Many fall victim to oxidative damage from free radicals, which are released as the immune system goes into inflammatory overdrive to clear up the mess. Last year, a team led by neurobiologist David Schubert of the Salk Institute for Biological Studies in La Jolla, California, showed that cerium oxide nanoparticles can protect cultures of mouse brain cells from
“The particles were able to protect the neurons from a powerful oxidising agent”
If those fragile wires break or corrode, the sensor becomes useless. Now a wireless sensor has been developed that detects substances through their effect on an applied magnetic field. “This is a wireless technology you can embed in any environment where sub-millimetre wiring is a risk, either due to spark risk or because of its fragility,” says the sensor’s developer, Mike Gibbs, an expert in engineering materials at the University of Sheffield in the UK. Typical molecular sensors, for example, use 1-micrometre-long silicon cantilevers that ping up and down like a diving board when the target molecule lands on them. This vibrates a piezoelectric crystal, producing a fluctuating current of
the same frequency. Wires connecting the crystal to a sensing circuit allow the device to register the cantilever’s motion. To build his wireless sensor, Gibbs applied a 100-nanometre-thick magnetic film to a silicon nitride cantilever. “Pinging” the cantilever with a field from an external electromagnetic coil sets it vibrating. That vibration in turn induces a current in the coil at the same frequency. When a molecule or pathogen of interest lands on the cantilever it will alter this frequency
“The absence of exposed electrical connections could be very useful”
by a telltale amount. Because there are no wires to the cantilever, it can be placed in a spark-free environment, with the coil at a safe remove. Gibbs has filed a patent on the idea, which he presented at an Institute of Nanotechnology conference in London last week. The absence of exposed electrical connections could be very useful in some applications, says Ian Eastwood of Authentix, a security technology firm based in Dunnington, UK. “Airlines have asked us to look into ways of sensing contaminated aviation fuel to prevent the equivalent of someone putting sugar in a car’s fuel tank. Removing spark risk could be one way we could do this.” Paul Marks ● www.newscientist.com
22/1/07 3:07:52 pm