Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Jagged graphene can slice into cell membranes

11.07.2013
A collaboration of biologists, engineers, and material scientists at Brown University has found that jagged edges of graphene can easily pierce cell membranes, allowing graphene to enter the cell and disrupt normal function.

Understanding the mechanical forces of nanotoxicity should help engineers design safer materials at the nanoscale.


Rough edges at the nanoscale
The bottom corner of a piece of graphene penetrates a cell membrane. Mechanical properties — rough edges, sharp corners — can make graphene dangerous to human cells. Scale bar represents two microns. Credit: Kane lab/Brown University

Researchers from Brown University have shown how tiny graphene microsheets — ultra-thin materials with a number of commercial applications — could be big trouble for human cells.

The research shows that sharp corners and jagged protrusions along the edges of graphene sheets can easily pierce cell membranes. After the membrane is pierced, an entire graphene sheet can be pulled inside the cell where it may disrupt normal function. The new insight may be helpful in finding ways to minimize the potential toxicity of graphene, said Agnes Kane, chair of the Department of Pathology and Laboratory Medicine at Brown and one of the study’s authors.

“At a fundamental level, we want understand the features of these materials that are responsible for how they interact with cells,” Kane said. “If there’s some feature that is responsible for its toxicity, then maybe the engineers can engineer it out.”

The findings were published online July 9 in Proceedings of the National Academy of Sciences.

Discovered about a decade ago, graphene is a sheet of carbon just one atom thick. It is incredibly strong despite being so thin and has remarkable electronic, mechanical, and photonic properties. Commercial applications in small electronic devices, solar cells, batteries and even medical devices are just around the corner. But not much is known about what effect these materials might have if they get inside the body either during the manufacturing process or during a product’s lifecycle.

“These materials can be inhaled unintentionally, or they may be intentionally injected or implanted as components of new biomedical technologies,” said Robert Hurt, professor of engineering and one of the study’s authors. “So we want to understand how they interact with cells once inside the body.”

These latest findings come from an ongoing collaboration between biologists, engineers, and material scientists at Brown aimed at understanding the toxic potential of a wide variety of nanomaterials. Their work on graphene started with some seemingly contradictory findings.

Preliminary research by Kane’s biology group had shown that graphene sheets can indeed enter cells, but it wasn’t clear how they got there. Huajian Gao, professor of engineering, tried to explain those results using powerful computer simulations, but he ran into a problem. His models, which simulate interactions between graphene and cell membranes at the molecular level, suggested that it would be quite rare for a microsheet to pierce a cell. The energy barrier required for a sheet to cut the membrane was simply too high, even when the sheet hit edge first.

The problem turned out to be that those initial simulations assumed a perfectly square piece of graphene. In reality, graphene sheets are rarely so pristine. When graphene is exfoliated, or peeled away from thicker chunks of graphite, the sheets come off in oddly shaped flakes with jagged protrusions called asperities. When Gao reran his simulations with asperities included, the sheets were able to pierce the membrane much more easily.

Annette von dem Bussche, assistant professor of pathology and laboratory medicine, was able to verify the model experimentally. She placed human lung, skin and immune cells in Petri dishes along with graphene microsheets. Electron microscope images confirmed that graphene entered the cells starting at rough edges and corners. The experiments showed that even fairly large graphene sheets of up to 10 micrometers could be completely internalized by a cell.

“The engineers and the material scientists can analyze and describe these materials in great detail,” Kane said. “That allows us to better interpret the biological impacts of these materials. It’s really a wonderful collaboration.”

From here, the researchers will look in more detail into what happens once a graphene sheet gets inside the cell. But Kane says this initial study provides an important start in understanding the potential for graphene toxicity.

“This is about the safe design of nanomaterials,” she said. “They’re man-made materials, so we should be able to be clever and make them safer.”

Other contributors to the study were Brown graduate students Yinfeng Li (now a professor at Shanghai Jiao Tong University), Hongyan Yuan, and Megan Creighton. The research was supported by the National Science Foundation (grants CMMI-1028530 and CBET-1132446) and the Superfund Research Program of the National Institute of Environmental Health Sciences (grant P42 ES013660).

Editors: Brown University has a fiber link television studio available for domestic and international live and taped interviews, and maintains an ISDN line for radio interviews. For more information, call (401) 863-2476.

Kevin Stacey | EurekAlert!
Further information:
http://www.brown.edu

More articles from Physics and Astronomy:

nachricht Water without windows: Capturing water vapor inside an electron microscope
13.12.2017 | Okinawa Institute of Science and Technology (OIST) Graduate University

nachricht Columbia engineers create artificial graphene in a nanofabricated semiconductor structure
13.12.2017 | Columbia University School of Engineering and Applied Science

All articles from Physics and Astronomy >>>

The most recent press releases about innovation >>>

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

Im Focus: Long-lived storage of a photonic qubit for worldwide teleportation

MPQ scientists achieve long storage times for photonic quantum bits which break the lower bound for direct teleportation in a global quantum network.

Concerning the development of quantum memories for the realization of global quantum networks, scientists of the Quantum Dynamics Division led by Professor...

Im Focus: Electromagnetic water cloak eliminates drag and wake

Detailed calculations show water cloaks are feasible with today's technology

Researchers have developed a water cloaking concept based on electromagnetic forces that could eliminate an object's wake, greatly reducing its drag while...

Im Focus: Scientists channel graphene to understand filtration and ion transport into cells

Tiny pores at a cell's entryway act as miniature bouncers, letting in some electrically charged atoms--ions--but blocking others. Operating as exquisitely sensitive filters, these "ion channels" play a critical role in biological functions such as muscle contraction and the firing of brain cells.

To rapidly transport the right ions through the cell membrane, the tiny channels rely on a complex interplay between the ions and surrounding molecules,...

Im Focus: Towards data storage at the single molecule level

The miniaturization of the current technology of storage media is hindered by fundamental limits of quantum mechanics. A new approach consists in using so-called spin-crossover molecules as the smallest possible storage unit. Similar to normal hard drives, these special molecules can save information via their magnetic state. A research team from Kiel University has now managed to successfully place a new class of spin-crossover molecules onto a surface and to improve the molecule’s storage capacity. The storage density of conventional hard drives could therefore theoretically be increased by more than one hundred fold. The study has been published in the scientific journal Nano Letters.

Over the past few years, the building blocks of storage media have gotten ever smaller. But further miniaturization of the current technology is hindered by...

Im Focus: Successful Mechanical Testing of Nanowires

With innovative experiments, researchers at the Helmholtz-Zentrums Geesthacht and the Technical University Hamburg unravel why tiny metallic structures are extremely strong

Light-weight and simultaneously strong – porous metallic nanomaterials promise interesting applications as, for instance, for future aeroplanes with enhanced...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

See, understand and experience the work of the future

11.12.2017 | Event News

Innovative strategies to tackle parasitic worms

08.12.2017 | Event News

AKL’18: The opportunities and challenges of digitalization in the laser industry

07.12.2017 | Event News

 
Latest News

A whole-body approach to understanding chemosensory cells

13.12.2017 | Health and Medicine

Water without windows: Capturing water vapor inside an electron microscope

13.12.2017 | Physics and Astronomy

Cellular Self-Digestion Process Triggers Autoimmune Disease

13.12.2017 | Life Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>