For the first time researchers have succeeded in placing a layer of graphene on top of a stable fatty lipid monolayer. Surrounded by a protective shell of lipids, graphene could enter the body and function as a versatile sensor. The results are the first step towards such a shell, and have been published in the journal Nanoscale on 28 September 2016.

In contrast to previous work, the researchers observed a stable structure when graphene is placed on a single layer of lipids. A patent application has been submitted for these findings. PhD candidate Lia Lima and co-workers made this discovery under the supervision of chemist Grégory Schneider.

Graphene

Graphene is a surface material that consists of a single layer of carbon atoms. It is extremely thin, strong and flexible. In addition, graphene is highly desired in the technological world for its effective conduction of electricity. The applications of graphene vary widely. ‘Graphene is particularly sensitive and can respond to its environment in the body,’ says Schneider. Given this sensitivity, future applications for the body could include such devices as biosensors and systems that pinpoint the right spot for performing diagnosis.

Bonding with graphene

Hard inorganic materials are often used as a support to make graphene suitable for these applications. However, these hard materials are not ideal for using graphene in the body. Scientists are therefore looking for soft, organic molecules - in this case lipids - to bind with graphene.

Lipids on graphene

Lipids are fats that can be found in the protective layer of a cell – the cell membrane. This membrane mainly consists of a double layer of lipids. If graphene can be placed between these two layers, it could travel through the body freely. ‘This is a method that is already used with cancer medicines,’ Schneider explains. ‘We created a single layer of lipids in the lab and transferred graphene on top: this is a first step towards mimicking the cell membrane.’

Measurements

Through their research the scientists discovered that a layer of lipids provides good support to graphene. The researchers used infrared measurements to prove the stability of the lipid layer. They also found that the lipids improve the electrical conduction of graphene, an effect that holds promise for future applications. Improvements in electrical conduction will make it possible to measure the electrical signals emitted by graphene in the body. These signals provide information about the environment of graphene, such as the acidity or the presence of certain proteins.

Nanosensor

Eventually, if graphene is stabilised by lipids, it could travel throughout the body. ‘However, we still have a long way to go,’ says Schneider. ‘The next step is to place a lipid layer on both sides of the graphene, like a sandwich.’

The publication can be seen on the cover of Nanoscale.