Scientists have long been on a quest to find a way to implant electrodes that interface with neurons into the human brain. If successful, the idea could have huge implications for the treatment of Parkinson's disease and other neurological disorders. Last month, a team of researchers from Italy and the UK made a huge step forward by showing that the world's favorite wonder-material, graphene, can successfully interface with neurons.
Previous efforts by other groups using treated graphene had created an interface with a very low signal to noise ratio. But an interdisciplinary collaborative effort by the University of Trieste and the Cambridge Graphene Centre has developed a significantly improved electrode by working with untreated graphene.
"For the first time we interfaced graphene to neurons directly," said Professor 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 signaling properties unaltered. This is the first functional study of neuronal synaptic activity using uncoated graphene based materials."
Prior to experimenting with graphene-based substrates (GBS), scientists implanted microelectrodes based on tungsten and silicon. Proof-of-concept experiments were successful, but these materials seem to suffer from the same fatal flaws. The body's reaction to the insertion trauma is to form scarring tissue, inhibiting clear electrical signals. The structures were also prone to disconnecting, due to the stiffness of the materials, which were unsuitable for a semi-fluid organic environment.
Pure graphene is promising because it is flexible, non-toxic, and does not impair other cellular activity.
The team's experiments on rat brain cell cultures showed that the untreated graphene electrodes interfaced well with neurons, transmitting electrical impulses normally with none of the adverse reactions seen previously.
The biocompatibility of graphene could allow it to be used to make graphene microelectrodes that could help measure, harness and control an impaired brain's functions. It could be used to restore lost sensory functions to treat paralysis, control prosthetic devices such a robotic limbs for amputees and even control or diminish the impact of the out-of-control electrical impulses that cause motor disorders such as Parkinson's and epilepsy.
"We are currently involved in frontline research in graphene technology towards biomedical applications," said Professor Maurizio Prato from the University of Trieste. "In this scenario, the development and translation in neurology of graphene-based high-performance bio-devices requires the exploration of the interactions between graphene nano and micro-sheets with the sophisticated signaling machinery of nerve cells. Our work is only a first step in that direction."
The research was funded by the Graphene Flagship, a European initiative that aims to connect theoretical and practical fields and reduce the time that graphene products spend in laboratories before being brought to market.