Graphene electrodes can safely interact with neurons

Scientists have developed graphene electrodes that can be implanted in the brain to control robotic arms in amputees or help restore sensory functions in patients with motor disorders such as Parkinson's disease.
By interfacing directly between the brain and the outside world we can now harness and control some of its functions, researchers said. For instance, by measuring the brain's electrical impulses, sensory functions can be recovered.
"For the first time we interfaced graphene to neurons directly," said Laura Ballerini of the University of Trieste in Italy.
"We then tested the ability of neurons to generate electrical signals known to represent brain activities, and found that the neurons retained their neuronal signalling properties unaltered," Ballerini said.

"This is the first functional study of neuronal synaptic activity using uncoated graphene based materials," she said.
This can be used to control robotic arms for amputee patients or any number of basic processes for paralysed patients - from speech to movement of objects in the world around them.

Alternatively, by interfering with these electrical impulses, motor disorders (such as epilepsy or Parkinson's) can start to be controlled.
Scientists, including those from University of Cambridge in UK, have made this possible by developing electrodes that can be placed deep within the brain.
These electrodes connect directly to neurons and transmit their electrical signals away from the body, allowing their meaning to be decoded.

However, the interface between neurons and electrodes has often been problematic - not only do the electrodes need to be highly sensitive to electrical impulses, but they need to be stable in the body without altering the tissue they measure.
Often, modern electrodes (based on tungsten or silicon) suffer from partial or complete loss of signal over time.
This is often caused by the formation of scar tissue from the electrode insertion, which prevents the electrode from moving with the natural movements of the brain due to its rigid nature.
Graphene has been shown to be a promising material to solve these problems, because of its excellent conductivity, flexibility, biocompatibility and stability within the body.

Based on experiments conducted in rat brain cell cultures, the researchers found that untreated graphene electrodes interfaced well with neurons.
By studying the neurons with electron microscopy and immunofluorescence the researchers found that they remained healthy, transmitting normal electric impulses and, importantly, none of the adverse reactions which lead to the damaging scar tissue were seen.
According to the researchers, this is the first step towards using pristine graphene-based materials as an electrode for a neuro-interface.
The study was published in the journal ACS Nano.