Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Functional materials: Two ways to kill

31.08.2012
Graphene-based materials kill bacteria through one of two possible mechanisms. Researchers at A*STAR Singapore Institute of Manufacturing Technology and co-workers have now compared the antibacterial activity of graphite, graphite oxide, graphene oxide and reduced graphene oxide using the model bacterium Escherichia coli.
The discovery of graphene has brought much excitement to the nanotechnology community. Much of this excitement is due to the possibility of deriving graphene-based materials with applications in electronics, energy storage, sensing and biomedical devices. Despite the potential, however, there is a real concern that graphene-based materials may have deleterious effects on human health and the natural environment.

One particularly interesting aspect of this subject is the toxic effects of graphene-based materials on the microscopic world of bacteria. For this very reason, Jun Wei at the A*STAR Singapore Institute of Manufacturing Technology and co-workers have now compared the antibacterial activity of graphite, graphite oxide, graphene oxide and reduced graphene oxide using the model bacterium Escherichia coli. They showed that the two graphene-based materials kill substantially more bacteria than two graphite-based materials — with graphene oxide being the top performer.

Interestingly, graphene oxide particles had the smallest size of all the four graphene materials as measured by dynamic light scattering. Wei and co-workers believe that particles of reduced graphene oxide were larger because they aggregated both laterally and in three dimensions.

In fact, the size of the particles could well be the key to why graphene oxide is so deadly to bacteria. When the researchers studied the affected cells using scanning electron microscopy, they saw that most of the E. coli cells were individually wrapped by layers of graphene oxide. In contrast, E. coli cells were usually embedded in the larger reduced-graphene-oxide aggregates (see image). A similar cell-trapping mechanism was operational in the graphite-based materials.

So why does cell-wrapping kill more cells than cell-trapping? The researchers believe that the direct contact of cell surface with graphene causes membrane stress and irreversible damage.

Wei and co-workers also investigated chemical mechanisms by which the materials could disrupt and kill bacteria. They found that the oxidation of glutathione, an important cellular antioxidant, occurred on exposure to graphite and reduced graphene oxide. “It might be that these structures act as conducting bridges extracting electrons from glutathione molecules and releasing them into the external environment,” says Wei.

Intriguingly, while the effect of the membrane-disrupting mechanisms dies away after four hours of incubation, the oxidation mechanism shows only minor changes.

“With the knowledge obtained in this study, we envision that physicochemical properties of graphene-based materials, such as the density of functional groups, size and conductivity can be better tailored to either reduce environmental risks or increase application potential,” says Wei.

The A*STAR-affiliated researchers contributing to this research are from the Singapore Institute of Manufacturing Technology

References:
Liu, S., Zeng, T. H., Hofmann, M., Burcombe, E., Wei, J. et al. Antibacterial activity of graphite, graphite oxide, graphene oxide and reduced graphene oxide: membrane and oxidative stress. ACS Nano 5, 6971–6980 (2011).

A*STAR Research | Research asia research news
Further information:
http://www.a-star.edu.sg
http://www.researchsea.com

More articles from Materials Sciences:

nachricht Physicists gain new insights into nanosystems with spherical confinement
27.07.2017 | Johannes Gutenberg Universitaet Mainz

nachricht Getting closer to porous, light-responsive materials
26.07.2017 | Kyoto University

All articles from Materials Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Abrupt motion sharpens x-ray pulses

Spectrally narrow x-ray pulses may be “sharpened” by purely mechanical means. This sounds surprisingly, but a team of theoretical and experimental physicists developed and realized such a method. It is based on fast motions, precisely synchronized with the pulses, of a target interacting with the x-ray light. Thereby, photons are redistributed within the x-ray pulse to the desired spectral region.

A team of theoretical physicists from the MPI for Nuclear Physics (MPIK) in Heidelberg has developed a novel method to intensify the spectrally broad x-ray...

Im Focus: Physicists Design Ultrafocused Pulses

Physicists working with researcher Oriol Romero-Isart devised a new simple scheme to theoretically generate arbitrarily short and focused electromagnetic fields. This new tool could be used for precise sensing and in microscopy.

Microwaves, heat radiation, light and X-radiation are examples for electromagnetic waves. Many applications require to focus the electromagnetic fields to...

Im Focus: Carbon Nanotubes Turn Electrical Current into Light-emitting Quasi-particles

Strong light-matter coupling in these semiconducting tubes may hold the key to electrically pumped lasers

Light-matter quasi-particles can be generated electrically in semiconducting carbon nanotubes. Material scientists and physicists from Heidelberg University...

Im Focus: Flexible proximity sensor creates smart surfaces

Fraunhofer IPA has developed a proximity sensor made from silicone and carbon nanotubes (CNT) which detects objects and determines their position. The materials and printing process used mean that the sensor is extremely flexible, economical and can be used for large surfaces. Industry and research partners can use and further develop this innovation straight away.

At first glance, the proximity sensor appears to be nothing special: a thin, elastic layer of silicone onto which black square surfaces are printed, but these...

Im Focus: 3-D scanning with water

3-D shape acquisition using water displacement as the shape sensor for the reconstruction of complex objects

A global team of computer scientists and engineers have developed an innovative technique that more completely reconstructs challenging 3D objects. An ancient...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Clash of Realities 2017: Registration now open. International Conference at TH Köln

26.07.2017 | Event News

Closing the Sustainability Circle: Protection of Food with Biobased Materials

21.07.2017 | Event News

»We are bringing Additive Manufacturing to SMEs«

19.07.2017 | Event News

 
Latest News

New 3-D imaging reveals how human cell nucleus organizes DNA and chromatin of its genome

28.07.2017 | Health and Medicine

Heavy metals in water meet their match

28.07.2017 | Power and Electrical Engineering

Oestrogen regulates pathological changes of bones via bone lining cells

28.07.2017 | Life Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>