Tag Archives: University of Castilla-La Mancha

Human lung enzyme can degrade graphene

Caption: A human lung enzyme can biodegrade graphene. Credit: Fotolia Courtesy: Graphene Flagship

The big European Commission research programme, Grahene Flagship, has announced some new work with widespread implications if graphene is to be used in biomedical implants. From a August 23, 2018 news item on ScienceDaily,

Myeloperoxidase — an enzyme naturally found in our lungs — can biodegrade pristine graphene, according to the latest discovery of Graphene Flagship partners in CNRS, University of Strasbourg (France), Karolinska Institute (Sweden) and University of Castilla-La Mancha (Spain). Among other projects, the Graphene Flagship designs based like flexible biomedical electronic devices that will interfaced with the human body. Such applications require graphene to be biodegradable, so our body can be expelled from the body.

An August 23, 2018 Grapehene Flagship press release (mildly edited version on EurekAlert), which originated the news item, provides more detail,

To test how graphene behaves within the body, researchers analysed how it was broken down with the addition of a common human enzyme – myeloperoxidase or MPO. If a foreign body or bacteria is detected, neutrophils surround it and secrete MPO, thereby destroying the threat. Previous work by Graphene Flagship partners found that MPO could successfully biodegrade graphene oxide.

However, the structure of non-functionalized graphene was thought to be more resistant to degradation. To test this, the team looked at the effects of MPO ex vivo on two graphene forms; single- and few-layer.

Alberto Bianco, researcher at Graphene Flagship Partner CNRS, explains: “We used two forms of graphene, single- and few-layer, prepared by two different methods in water. They were then taken and put in contact with myeloperoxidase in the presence of hydrogen peroxide. This peroxidase was able to degrade and oxidise them. This was really unexpected, because we thought that non-functionalized graphene was more resistant than graphene oxide.”

Rajendra Kurapati, first author on the study and researcher at Graphene Flagship Partner CNRS, remarks how “the results emphasize that highly dispersible graphene could be degraded in the body by the action of neutrophils. This would open the new avenue for developing graphene-based materials.”

With successful ex-vivo testing, in-vivo testing is the next stage. Bengt Fadeel, professor at Graphene Flagship Partner Karolinska Institute believes that “understanding whether graphene is biodegradable or not is important for biomedical and other applications of this material. The fact that cells of the immune system are capable of handling graphene is very promising.”

Prof. Maurizio Prato, the Graphene Flagship leader for its Health and Environment Work Package said that “the enzymatic degradation of graphene is a very important topic, because in principle, graphene dispersed in the atmosphere could produce some harm. Instead, if there are microorganisms able to degrade graphene and related materials, the persistence of these materials in our environment will be strongly decreased. These types of studies are needed.” “What is also needed is to investigate the nature of degradation products,” adds Prato. “Once graphene is digested by enzymes, it could produce harmful derivatives. We need to know the structure of these derivatives and study their impact on health and environment,” he concludes.

Prof. Andrea C. Ferrari, Science and Technology Officer of the Graphene Flagship, and chair of its management panel added: “The report of a successful avenue for graphene biodegradation is a very important step forward to ensure the safe use of this material in applications. The Graphene Flagship has put the investigation of the health and environment effects of graphene at the centre of its programme since the start. These results strengthen our innovation and technology roadmap.”

Here’s a link to and a citation for the paper,

Degradation of Single‐Layer and Few‐Layer Graphene by Neutrophil Myeloperoxidase by Dr. Rajendra Kurapati, Dr. Sourav P. Mukherjee, Dr. Cristina Martín, Dr. George Bepete, Prof. Ester Vázquez, Dr. Alain Pénicaud, Prof. Dr. Bengt Fadeel, Dr. Alberto Bianco. Angewandte Chemie https://doi.org/10.1002/anie.201806906 First published: 13 July 2018

This paper is behind a paywall.

Calming a synapse (part of a neuron) with graphene flakes

As we continue to colonize our own brains, there’s more news of graphene and neurons (see my Feb. 1, 2016 post featuring research from the same team in Italy featured in this post). A May 10, 2016 news item on ScienceDaily highlights work that could be used for epilepsy,

Innovative graphene technology to buffer the activity of synapses– this is the idea behind a recently-published study in the journal ACS Nano coordinated by the International School for Advanced Studies in Trieste (SISSA) and the University of Trieste. In particular, the study showed how effective graphene oxide flakes are at interfering with excitatory synapses, an effect that could prove useful in new treatments for diseases like epilepsy.

I guess the press release took a while to make its way through translation, here’s more from the April 10, 2016 SISSA (International School for Advanced Studies) press release (also on EurekAlert),

The laboratory of SISSA’s Laura Ballerini in collaboration with the University of Trieste, the University of Manchester and the University of Castilla -la Mancha, has discovered a new approach to modulating synapses. This methodology could be useful for treating diseases in which electrical nerve activity is altered. Ballerini and Maurizio Prato (University of Trieste) are the principal investigators of the project within the European flagship on graphene, a far-reaching 10-year international collaboration (one billion euros in funding) that studies innovative uses of the material.

Traditional treatments for neurological diseases generally include drugs that act on the brain or neurosurgery. Today however, graphene technology is showing promise for these types of applications, and is receiving increased attention from the scientific community. The method studied by Ballerini and colleagues uses “graphene nano-ribbons” (flakes) which buffer activity of synapses simply by being present.

“We administered aqueous solutions of graphene flakes to cultured neurons in ‘chronic’ exposure conditions, repeating the operation every day for a week. Analyzing functional neuronal electrical activity, we then traced the effect on synapses” says Rossana Rauti, SISSA researcher and first author of the study.

In the experiments, size of the flakes varied (10 microns or 80 nanometers) as well as the type of graphene: in one condition graphene was used, in another, graphene oxide. “The ‘buffering’ effect on synaptic activity happens only with smaller flakes of graphene oxide and not in other conditions,” says Ballerini. “The effect, in the system we tested, is selective for the excitatory synapses, while it is absent in inhibitory ones”

A Matter of Size

What is the origin of this selectivity? “We know that in principle graphene does not interact chemically with synapses in a significant way- its effect is likely due to the mere presence of synapses,” explains SISSA researcher and one of the study’s authors, Denis Scaini. “We do not yet have direct evidence, but our hypothesis is that there is a link with the sub-cellular organization of the synaptic space.”

A synapse is a contact point between one neuron and another where the nervous electrical signal “jumps” between a pre and post-synaptic unit. [emphasis mine] There is a small gap or discontinuity where the electrical signal is “translated” by a neurotransmitter and released by pre-synaptic termination into the extracellular space and reabsorbed by the postsynaptic space, to be translated again into an electrical signal. The access to this space varies depending on the type of synapses: “For the excitatory synapses, the structure’s organization allows higher exposure for the graphene flakes interaction, unlike inhibitory synapses, which are less physically accessible in this experimental model,” says Scaini.

Another clue that distance and size could be crucial in the process is found in the observation that graphene performs its function only in the oxidized form. “Normal graphene looks like a stretched and stiff sheet while graphene oxide appears crumpled, and thus possibly favoring interface with the synaptic space, ” adds Rauti.

Administering graphene flake solutions leaves the neurons alive and intact. For this reason the team thinks they could be used in biomedical applications for treating certain diseases. “We may imagine to target a drug by exploiting the apparent flakes’ selectivity for synapses, thus targeting directly the basic functional unit of neurons”concludes Ballerini.

That’s a nice description of neurons, synapses, and neurotransmitters.

Here’s a link to and a citation for the paper,

Graphene Oxide Nanosheets Reshape Synaptic Function in Cultured Brain Networks by Rossana Rauti, Neus Lozano, Veronica León, Denis Scaini†, Mattia Musto, Ilaria Rago, Francesco P. Ulloa Severino, Alessandra Fabbro, Loredana Casalis, Ester Vázquez, Kostas Kostarelos, Maurizio Prato, and Laura Ballerini. ACS Nano, 2016, 10 (4), pp 4459–4471
DOI: 10.1021/acsnano.6b00130 Publication Date (Web): March 31, 2016

Copyright © 2016 American Chemical Society

This paper is behind a paywall.

Graphene and neurons in a UK-Italy-Spain collaboration

There’s been a lot of talk about using graphene-based implants in the brain due to the material’s flexibility along with its other properties. A step forward has been taking according to a Jan. 29, 2016 news item on phys.org,

Researchers have successfully demonstrated how it is possible to interface graphene – a two-dimensional form of carbon – with neurons, or nerve cells, while maintaining the integrity of these vital cells. The work may be used to build graphene-based electrodes that can safely be implanted in the brain, offering promise for the restoration of sensory functions for amputee or paralysed patients, or for individuals with motor disorders such as epilepsy or Parkinson’s disease.

A Jan. 29, 2016 Cambridge University press release (also on EurekAlert), which originated the news item, provides more detail,

Previously, other groups had shown that it is possible to use treated graphene to interact with neurons. However the signal to noise ratio from this interface was very low. By developing methods of working with untreated graphene, the researchers retained the material’s electrical conductivity, making it a significantly better electrode.

“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 signalling properties unaltered. This is the first functional study of neuronal synaptic activity using uncoated graphene based materials.”

Our understanding of the brain has increased to such a degree that by interfacing directly between the brain and the outside world we can now harness and control some of its functions. For instance, by measuring the brain’s electrical impulses, sensory functions can be recovered. 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 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.

Too often the modern electrodes used for this interface (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. In future, the researchers will investigate how different forms of graphene, from multiple layers to monolayers, are able to affect neurons, and whether tuning the material properties of graphene might alter the synapses and neuronal excitability in new and unique ways. “Hopefully this will pave the way for better deep brain implants to both harness and control the brain, with higher sensitivity and fewer unwanted side effects,” said Ballerini.

“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 biodevices requires the exploration of the interactions between graphene nano- and micro-sheets with the sophisticated signalling machinery of nerve cells. Our work is only a first step in that direction.”

“These initial results show how we are just at the tip of the iceberg when it comes to the potential of graphene and related materials in bio-applications and medicine,” said Professor Andrea Ferrari, Director of the Cambridge Graphene Centre. “The expertise developed at the Cambridge Graphene Centre allows us to produce large quantities of pristine material in solution, and this study proves the compatibility of our process with neuro-interfaces.”

The research was funded by the Graphene Flagship [emphasis mine],  a European initiative which promotes a collaborative approach to research with an aim of helping to translate graphene out of the academic laboratory, through local industry and into society.

Here’s a link to and a citation for the paper,

Graphene-Based Interfaces Do Not Alter Target Nerve Cells by Alessandra Fabbro, Denis Scaini, Verónica León, Ester Vázquez, Giada Cellot, Giulia Privitera, Lucia Lombardi, Felice Torrisi, Flavia Tomarchio, Francesco Bonaccorso, Susanna Bosi, Andrea C. Ferrari, Laura Ballerini, and Maurizio Prato. ACS Nano, 2016, 10 (1), pp 615–623 DOI: 10.1021/acsnano.5b05647 Publication Date (Web): December 23, 2015

Copyright © 2015 American Chemical Society

This paper is behind a paywall.

There are a couple things I found a bit odd about this project. First, all of the funding is from the Graphene Flagship initiative. I was expecting to see at least some funding from the European Union’s other mega-sized science initiative, the Human Brain Project. Second, there was no mention of Spain nor were there any quotes from the Spanish researchers. For the record, the Spanish institutions represented were: University of Castilla-La Mancha, Carbon Nanobiotechnology Laboratory, and the Basque Foundation for Science.