Tag Archives: Scuola Internazionale Superiore di Studi Avanzati (SISSA)

Impact of graphene flakes (nanoparticles) on neurons

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This research suggests that graphene flakes might have an impact on anxiety-related behaviour. If I read the work correctly, the graphene flakes don’t exacerbate anxiety but, instead, may provide relief.

A March 10, 2021 news item on phys.org announces the research into graphene flakes and neurons (rat), Note: Links have been removed,

Effective, specific, with a reversible and non-harmful action: the identikit of the perfect biomaterial seems to correspond to graphene flakes, the subject of a new study carried out by SISSA—International School for Advanced Studies of Trieste, Catalan Institute of Nanoscience and Nanotechnology (ICN2) of Barcelona, and the National Graphene Institute of the University of Manchester, as part of the European Graphene Flagship project. This nanomaterial has demonstrated the ability to interact with the functions of the nervous system in vertebrates in a very specific manner, interrupting the building up of a pathological process that leads to anxiety-related behavior.

“We previously showed that when graphene flakes are delivered to neurons they interfere spontaneously with excitatory synapses by transiently preventing glutamate release from presynaptic terminals,” says Laura Ballerini of SISSA, the leader of the team that carried out the research study “Graphene oxide prevents lateral amygdala dysfunctional synaptic plasticity and reverts long lasting anxiety behavior in rats,” recently published in Biomaterials.

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A March 10, 2021 Scuola Internazionale Superiore di Studi Avanzati (SISSA) press release (also on EurekAlert), which originated the news item, provides more detail,

“We investigated whether such a reduction in synaptic activity was sufficient to modify related behaviours, in particular the pathological ones that develop due to a transient and localised hyper-function of excitatory synapses”. This approach would fortify the strategy of selective and transient targeting of synapses to prevent the development of brain pathologies by using the so-called precise medicine treatments.

To test this hypothesis, the team focused on post-traumatic stress disorder (PTSD) and carried out the experiments in two phases, in vivo and in vitro.

“We analysed defensive behaviours caused in rats [emphasis mine] by the presence of a predator, using the exposure to cat odour, to induce an aversive memory” explains Audrey Franceschi Biagioni of SISSA, the first author of the study. “If exposed to the predator odour, the rat has a defensive response, holing up, and this experience is so well-imprinted in the memory, that when the animal is placed in the same context even six days later, the animal remembers the odour of the predator and acts the same protective behaviour. This is a well-known and consolidated model, that we used to reproduce a stress behaviour. Exposure to the predator can modify neuronal connections – a phenomenon that is technically known as plasticity – and increases synaptic activity in a specific area of the amygdala that therefore represented the target of our study to test the effects of the nanomaterial”.

Laura Ballerini adds: “We hypothesised that graphene flakes that we showed to temporarily inhibit excitatory synapses (without causing inflammation, damage to neurons or other side effects) could be injected in the lateral amygdala when the plasticity associated with memory was consolidated. If the nanomaterial was efficient in blocking excitatory synapses, it should inhibit plasticity and decrease the anxiety related response. And this is what happened: the animals that were administered with graphene flakes, after six days, “forgot” the anxiety related responses, rescuing their behaviour”.

The second part of the research was performed in vitro. “In vivo we could observe only behavioural changes and could not evaluate the impact of the graphene flakes on synapses,” explains Giada Cellot, researcher at SISSA and first author of the study together with Audrey Franceschi Biagioni. “In vitro experiments allowed to work on a simplified model, to get insight about the mechanisms through which the graphene flakes can interact with neurons. We used neuronal cultures obtained from the amygdala, the region of the brain where the stress response occurs, and we observed that the effects of nanomaterials were specific for the excitatory synapses and a short exposure to graphene flakes could prevent the pathological plasticity of the synapses”.

Thanks to these findings, graphene flakes have shown their potential as nanotools (biomedical tools composed of nanomaterials) that could act in a specific and reversible way on synaptic activity to interrupt a pathological process and therefore they might be used also to transport drugs or for other applications in the field of precision medicine.

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

Graphene oxide prevents lateral amygdala dysfunctional synaptic plasticity and reverts long lasting anxiety behavior in rats by Audrey Franceschi Biagionia1, Giada Cellot, Elisa Pati, Neus Lozano, Belén Ballesteros, Raffaele Casani, Norberto Cysne Coimbra, Kostas Kostarelos, Laura Ballerini. Biomaterials Volume 271, April 2021, 120749 DOI: https://doi.org/10.1016/j.biomaterials.2021.120749

This paper is open access.

Neuronal regenerative-interfaces made of cross-linked carbon nanotube films

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If I understand this research rightly, they are creating a film made of carbon nanotubes that can stimulate the growth of nerve cells (neurons) thus creating a ‘living/nonliving’ hybrid or as they call it in the press release a ‘biosynthetic hybrid’.

An August 2, 2019 news item on Nanowerk introduces the research (Note 1: There seem to be some translation issues; Note 2: Links have been removed),

Carbon nanotubes able to take on the desired shapes thanks to a special chemical treatment, called crosslinking and, at the same time, able to function as substrata for the growth of nerve cells, finely tuning their growth and activity.

The research published in ACS Nano (“Chemically Cross-Linked Carbon Nanotube Films Engineered to Control Neuronal Signaling”), is a new and important step towards the construction of neuronal regenerative-interfaces to repair spinal injuries.

The study is the new achievement of a long-term and, in terms of results, successful collaboration between the scientists Laura Ballerini of SISSA (Scuola Internazionale Superiore di Studi Avanzati), Trieste, and Maurizio Prato of the University of Trieste. The work team has also been assisted by CIC biomaGUNE of San Sebastián, Spain.

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Caption: Carbon nanotubes able to take on the desired shapes thanks to a special chemical treatment, called crosslinking and, at the same time, able to function as substrata for the growth of nerve cells, finely tuning their growth and activity. Credit: Rossana Rauti

An August 2, 2019 SISSA press release (also on EurekAlert), which originated the news item, adds detail,

The carbon nanotubes used in the research have been modified by appropriate chemical treatments: “For many years, in our laboratories we have been working on the chemical reactivity of carbon nanotubes, a fascinating but very difficult material to work. Thanks to our experience, we have crosslinked them or, to say it more clearly, we have treated the nanotubes so they could link themselves to one another thanks to specific chemical reactions. We have discovered that this procedure gives the material very interesting characteristics. For example, the material organises itself in a stable manner according to a precise shape, we choose: a tissue where nerve cells need to be planted, for example. Or around some electrodes” explains Professor Prato. “We know from previous research that nerve cells grow well on carbon nanotubes so they could be used as a surface to build hybrid devices to regenerate nerve tissues. It was necessary to ensure that this chemical modification did not compromise this process and study whether the interaction with neurons was altered”.

Towards biosynthetic hybrids

Professor Ballerini continues: “We have discovered that the chemical process has important effects because through this treatment we can modulate the activity of neurons, in terms of growth, adhesion and survival. These materials can also regulate the communication between neurons. We can say that the carpet of crosslinked carbon nanotubes interacts intensely and constructively with the nerve cells”. This interaction depends on how much the different carbon nanotubes are linked to each other, or rather crosslinked. The lower the link number among the nanotubes the higher the activity of neurons that grow on their surface. Through the chemical control of their properties, and of the links between them, it is possible to regulate the response of the neurons. Ballerini and Prato explain: “This is an intriguing result that emerges from the important and fruitful collaboration between our research groups involving advanced research in chemistry, nanoscience and neurobiology . This study provides a further step in the design of future biosynthetic hybrids to recover injured nerve tissues functions”.

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

Chemically Cross-Linked Carbon Nanotube Films Engineered to Control Neuronal Signaling by Myriam Barrejón, Rossana Rauti, Laura Ballerini, Maurizio Prato. ACS Nano2019 XXXXXXXXXX-XXX Publication Date:July 22, 2019 DOI: https://doi.org/10.1021/acsnano.9b02429 Copyright © 2019 American Chemical Society

This paper is behind a paywall.

Graphene flakes bring spintronics a step closer?

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Italian researchers are hoping that graphene flakes will be instrumental in the development of spintronics according to a March 14, 2018 news item on phys.org,

Graphene nanoflakes are promising for possible applications in the field of nanoelectronics, and the subject of a study recently published in Nano Letters. These hexagonal nanostructures exhibit quantum effects for modulating current flow. Thanks to their intrinsic magnetic properties, they could also represent a significant step forward in the field of spintronics. The study, conducted via computer analysis and simulations, was led by Massimo Capone.

A March 14, 2018 Scuola Internazionale Superiore di Studi Avanzati (SISSA) press release (also on EurekAlert), which originated the news item, expands on the theme,

“We have been able to observe two key phenomena by analysing the properties of graphene nanoflakes. Both are of great interest for possible future applications” explain Angelo Valli and Massimo Capone, authors of the study together with Adriano Amaricci and Valentina Brosco. The first phenomenon deals with the so-called interference between electrons and is a quantum phenomenon: «In nanoflakes, the electrons interfere with each other in a “destructive” manner if we measure the current in a certain configuration. This means that there is no transmission of current. This is a typically quantum phenomenon, which only occurs at very reduced sizes. By studying the graphene flakes we have understood that it is possible to bring this phenomenon to larger systems, therefore into the nano world and on a scale in which it is observable and can be exploited for possible uses in nanoelectronics». The two researchers explain that in what are called “Quantum interference transistors” destructive interference would be the “OFF” status. For the “ON” status, they say it is sufficient to remove the conditions for interference, thereby enabling the current to flow.

Magnetism and spintronics

But there’s more. In the study, the researchers demonstrated that the nanoflakes present new magnetic properties which are absent, for example, in an entire sheet of graphene: «The magnetism emerges spontaneously at their edges, without any external intervention. This enables the creation of a spin current». The union between the phenomena of quantum interference and of magnetism would allow to obtain almost complete spin polarization, with a huge potential in the field of spintronics, explain the researchers. These properties could be used, for example, in the memorising and processing information technologies, interpreting the spin as binary code. The electron spin, being quantised and having only two possible configurations (which we could call “up” and “down”), is very well suited for this kind of implementation.

Next step: the experimental test

To improve the efficiency of the possible device and the percentage of current polarization the researchers have also developed a protocol that envisages the interaction of the graphene flakes with a surface made of nitrogen and boron. «The results obtained are really interesting. This evidence now awaits the experimental test, to confirm what we have theoretically predicted» concludes Massimo Capone, head of the research and recently awarded the title of Outstanding Referee by the American Physical Society journal; in this way, each year, the journal indicates the male and female scientists who have distinguished themselves for their expertise in collaborating with the journal.

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

Quantum Interference Assisted Spin Filtering in Graphene Nanoflakes by Angelo Valli, Adriano Amaricci, Valentina Brosco, and Massimo Capone. Nano Lett., 2018, 18 (3), pp 2158–2164 DOI: 10.1021/acs.nanolett.8b00453 Publication Date (Web): February 23, 2018

Copyright © 2018 American Chemical Society

This paper is behind a paywall.

The nanotube of a thousand faces (similar nanomaterials behaving differently)

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Kudos to any one who recognizes the reference to the ‘man of a thousand faces’, Lon Chaney, a silent film horror star. As for the nanotubes, there’s this Sept. 14, 2016 news item on ScienceDaily,

Nanotubes can be used for many things: electrical circuits, batteries, innovative fabrics and more. Scientists have noted, however, that nanotubes, whose structures appear similar, can actually exhibit different properties, with important consequences in their applications. Carbon nanotubes and boron nitride nanotubes, for example, while nearly indistinguishable in their structure, can be different when it comes to friction. A study conducted by SISSA/CNR-IOM and Tel Aviv University created computer models of these crystals and studied their characteristics in detail and observed differences related to the material’s chirality. …

A Sept. 14, 2016 Scuola Internazionale Superiore di Studi Avanzati (SISSA) press release (PDF), which originated the news item, describes the research in more detail,

“We began with a series of experimental observations which showed that very similar nanotubes exhibit different frictional properties, with intensities ranging up to two orders of magnitude,” says Roberto Guerra, a researcher at CNR-IOM and the International School for Advanced Studies (SISSA) in Trieste, first author of the study. “This led us to hypothesize that the chirality of the materials may play a role in this phenomenon.” The study involving also Andrea Vanossi (CNR-IOM) and Erio Tosatti (SISSA), was conducted in collaboration with the University of Tel Aviv.

For materials, such as those used in the study, chirality is linked to the three-dimensional arrangement of the weft that form the nanotube. “If we wrap a sheet of lined paper around itself to form a tube, the angle that the lines form with the axis of the tube determines its chirality,” says Guerra. “In our work we reconstructed the behavior of double-walled nanototubes, which can be imagined as two tubes of slightly different diameters, one inside the other. We observed that the difference in chirality between the inner tube and the outer tube has a remarkable effect on the three-dimensional shape of the nanotubes.”

A polygonal tube

“If we continue with the paper metaphor, the difference in orientation between the lattice on the inner tube and the outer tube determine to what extent, and, in what way, planar regions (faces) along the tube will form,” says Guerra. To better understand what is meant by “faces,” imagine a cross section of the tube, which is polygonal rather than perfectly circular. “The smaller the difference in chirality, the clearer and more obvious the faces,” concludes Guerra. If, however, the difference in chirality becomes too large, the faces disappear and the nanotubes take on the classic cylindrical shape.

The faces appear spontaneously depending on the characteristics of the material. Double-walled carbon nanotubes tend to form with a greater difference in internal and external chirality compared to boron nitride. Therefore, the former usually maintains a cylindrical shape that allows for less friction. In further studies, Guerra and colleagues intend to work directly on measuring the level of friction between nanotubes.

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

Multiwalled nanotube faceting unravelled by Itai Leven, Roberto Guerra, Andrea Vanossi, Erio Tosatti, & Oded Hod. Nature Nanotechnology (2016) doi:10.1038/nnano.2016.151 Published online 22 August 2016

This paper is behind a paywall.