Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:


Functional materials: Two ways to kill

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

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:

More articles from Materials Sciences:

nachricht From ancient fossils to future cars
21.10.2016 | University of California - Riverside

nachricht Study explains strength gap between graphene, carbon fiber
20.10.2016 | Rice 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: New 3-D wiring technique brings scalable quantum computers closer to reality

Researchers from the Institute for Quantum Computing (IQC) at the University of Waterloo led the development of a new extensible wiring technique capable of controlling superconducting quantum bits, representing a significant step towards to the realization of a scalable quantum computer.

"The quantum socket is a wiring method that uses three-dimensional wires based on spring-loaded pins to address individual qubits," said Jeremy Béjanin, a PhD...

Im Focus: Scientists develop a semiconductor nanocomposite material that moves in response to light

In a paper in Scientific Reports, a research team at Worcester Polytechnic Institute describes a novel light-activated phenomenon that could become the basis for applications as diverse as microscopic robotic grippers and more efficient solar cells.

A research team at Worcester Polytechnic Institute (WPI) has developed a revolutionary, light-activated semiconductor nanocomposite material that can be used...

Im Focus: Diamonds aren't forever: Sandia, Harvard team create first quantum computer bridge

By forcefully embedding two silicon atoms in a diamond matrix, Sandia researchers have demonstrated for the first time on a single chip all the components needed to create a quantum bridge to link quantum computers together.

"People have already built small quantum computers," says Sandia researcher Ryan Camacho. "Maybe the first useful one won't be a single giant quantum computer...

Im Focus: New Products - Highlights of COMPAMED 2016

COMPAMED has become the leading international marketplace for suppliers of medical manufacturing. The trade fair, which takes place every November and is co-located to MEDICA in Dusseldorf, has been steadily growing over the past years and shows that medical technology remains a rapidly growing market.

In 2016, the joint pavilion by the IVAM Microtechnology Network, the Product Market “High-tech for Medical Devices”, will be located in Hall 8a again and will...

Im Focus: Ultra-thin ferroelectric material for next-generation electronics

'Ferroelectric' materials can switch between different states of electrical polarization in response to an external electric field. This flexibility means they show promise for many applications, for example in electronic devices and computer memory. Current ferroelectric materials are highly valued for their thermal and chemical stability and rapid electro-mechanical responses, but creating a material that is scalable down to the tiny sizes needed for technologies like silicon-based semiconductors (Si-based CMOS) has proven challenging.

Now, Hiroshi Funakubo and co-workers at the Tokyo Institute of Technology, in collaboration with researchers across Japan, have conducted experiments to...

All Focus news of the innovation-report >>>



Event News

#IC2S2: When Social Science meets Computer Science - GESIS will host the IC2S2 conference 2017

14.10.2016 | Event News

Agricultural Trade Developments and Potentials in Central Asia and the South Caucasus

14.10.2016 | Event News

World Health Summit – Day Three: A Call to Action

12.10.2016 | Event News

Latest News

Resolving the mystery of preeclampsia

21.10.2016 | Health and Medicine

Stanford researchers create new special-purpose computer that may someday save us billions

21.10.2016 | Information Technology

From ancient fossils to future cars

21.10.2016 | Materials Sciences

More VideoLinks >>>