NEWS
CHEMICAL SYNTHESIS
Electrons to replace lasers
MARIA BURKE
Molecular physicists have discovered that chemical reactions could be controlled by using electrons rather than lasers, providing a much cheaper alternative. The work could have applications in manufacturing chemicals from cancer drugs to computer electronics.
In quantum mechanics, particles behave MEDICINE AND HEALTH
Cellulose suit for implants
ANTHONY KING
Around 10m medical devices are implanted each year into patients, while one-third of patients suffer some complication as a result. Now, researchers in Switzerland have developed a way to protect implants by dressing them in a surgical membrane of cellulose hydrogel to make them more biocompatible with patients’ own tissues and body fluids. ‘It is more than 60 years since the
first medical implant was implanted in humans and no matter how hard we have tried to imitate nature, the body recognises the implant as foreign and tends to initiate a foreign body reaction, which tries to isolate and kill the implant,’ says Simone Bottan who leads ETH Zurich spin-off Hylomorph. Up to one-fifth of all implanted
patients require corrective intervention or implant replacement due to an immune response that wraps the implant in connective tissue (fibrosis), which is also linked with infections and can cause patients pain. Revision surgeries are costly and require lengthy recovery times. The new membrane is made by
growing bacteria in a bioreactor on micro-engineered silicone surfaces, pitted with a hexagonal arrangement of microwells. When imprinted onto the membrane, the microwells impede the formation of layers of fibroblasts and
other cells involved in fibrosis. The researchers ‘tuned’ the bacteria,
Acetobacter xylinum, to produce ca800 micron-thick membranes of cellulose nanofibrils that surgeons can wrap snuggly around implants. The cellulose membranes led to an 80% reduction of fibrotic tissue thickness in a pig model after six weeks, according to a study currently in press. Results after three and 12 months should be released in January 2018.
It is hoped the technology will
receive its first product market authorisation by 2020. First-in-man trials will focus on pacemakers and defibrillators and will be followed by breast reconstruction implants. The strategy will be to coat the implant with a soft cellulose hydrogel, consisting of 98% water and 2% cellulose fibres. ‘Fibrosis of implantables is a major medical problem,’ notes biomolecular engineer Joshua Doloff at Massachusetts Institute of Technology, adding that many coating technologies are under development. ‘[The claim] that no revision surgery
due to fibrosis will be needed is quite a strong claim to make,’ says Doloff, who would also like to see data on the coating’s robustness and longevity. The silicone topography was designed using standard microfabrication techniques used in the electronics industry, assisted by IBM Research Labs.
like waves and can be described by wave functions. If two or more particles are in the same quantum state and the phases of their wave functions remain constant, the system is said to be coherent, like photons - the basic packages of light energy - in a laser beam. Researchers have been investigating
how to use the effects induced by quantum coherence in atomic and molecular systems as the basis for controlling chemical reactions. This approach relies on laser beams of coherent photons inducing desired reaction pathways. So far, scientists have used laser beams to control dissociation of diatomic molecules. They speculated that the coherence in the resulting excited molecular species stems from the absorbed coherent laser radiation. Now a team from The Open University
and Tata Institute of Fundamental Research, Mumbai, has shown that such coherence can also arise from incoherent electrons (Nature Physics, doi:10.1038/nphys4289). When a diatomic molecule captures a low-energy electron, a relatively unstable molecular negative ion is formed. Subsequently, this excited ion decays by ejecting the extra electron, or alternatively the ion dissociates. Not much is known about these ions because their lifetimes are so short, but the researchers say these results point to unexplored dynamics that might open up new methods of chemical control. Low-energy electrons are important in
astrochemistry (synthesis of new molecules), radiation biology, plasma chemistry, atmospheric chemistry, radioactive waste management and nanolithography. The Open University’s Nigel Mason
comments that the ability to control chemical reactions is one of the major goals in chemistry, he says, enabling the manufacturing industry to reduce production costs and waste. ‘The discovery that an electron rather than a laser can control the process means that this approach is cheaper and faster,’ he says.
09 | 2017
7
SCIENCE PHOTO LIBRARY
Page 1 |
Page 2 |
Page 3 |
Page 4 |
Page 5 |
Page 6 |
Page 7 |
Page 8 |
Page 9 |
Page 10 |
Page 11 |
Page 12 |
Page 13 |
Page 14 |
Page 15 |
Page 16 |
Page 17 |
Page 18 |
Page 19 |
Page 20 |
Page 21 |
Page 22 |
Page 23 |
Page 24 |
Page 25 |
Page 26 |
Page 27 |
Page 28 |
Page 29 |
Page 30 |
Page 31 |
Page 32 |
Page 33 |
Page 34 |
Page 35 |
Page 36 |
Page 37 |
Page 38 |
Page 39 |
Page 40 |
Page 41 |
Page 42 |
Page 43 |
Page 44 |
Page 45 |
Page 46 |
Page 47 |
Page 48 |
Page 49 |
Page 50 |
Page 51 |
Page 52
