December 2021
Degradation of pristine graphene occurs in the human body when it interacts with a natural enzyme found in the lung. This was one of the findings of the Graphene Flagship members; the French National Center for Scientific Research (CNRS), the University of Strasbourg, the Karolinska Institute and the University of Castilla-La Mancha (UCLM).
Graphene-based products, including flexible biomedical electronic devices, are being designed to interact with the human body within the Graphene Flagship. If graphene is to be used for such biomedical applications, it must be biodegradable and therefore expelled from the body.
To assess how graphene behaves in the body, Alberto Bianco and his team at Graphene's flagship partner, the CNRS, conducted several tests to determine if graphene was broken down and how it interacted with the addition of a common human enzyme. The enzyme, myeloperoxidase (MPO), is a peroxide enzyme released by neutrophils, cells found in the lungs that are responsible for the removal of foreign bodies or bacteria that enter the body. If a foreign body or bacteria is detected inside the body, neutrophils surround it and secrete MPO, destroying the threat. Previous work by Graphene Flagship partners found that MPO biodegraded graphene oxide. However, the non-functionalized graphene structure was thought to be more resistant to degradation. To test this, Bianco and his team analyzed the effects of MPO, ex vivo, on two forms of graphene: a single-layered type and a multi-layered type.
Bianco says: "We used two forms of graphene, one and few layers, prepared with two different methods in water. They were then taken up and put in contact with myeloperoxidase in the presence of hydrogen peroxide. This peroxidase was able to degrade and oxidize them. This was really not expected, because we thought that non-functionalized graphene was stronger than graphene oxide."
Rajendra Kurapati, first author of the study, from Graphene's flagship partner CNRS, said: "The results emphasize that highly dispersible graphene could be degraded in the body by the action of neutrophils. This would open a new way to develop materials based on graphene."
In-vivo testing is the next stage. Bengt Fadeel, Professor at Graphene Partner Karolinska Institute, says: "Understanding whether or not graphene is biodegradable 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, leader of Work Package 4, said: "The enzymatic degradation of graphene is a very important issue, because, in principle, graphene dispersed in the atmosphere could cause some damage. On the other hand, if there are microorganisms capable of degrading graphene and its related substances, the persistence of these materials in our environment will be greatly reduced. These types of studies are necessary. What is also needed is to investigate the nature of the breakdown products. Once graphene is digested by enzymes, it could produce harmful derivatives. You need to know the structure of these derivatives and study their impact on health and the environment."
Prof. Andrea C. Ferrari, Graphene Flagship Science and Technology Officer, and chair of its management panel, added: "The report of a successful pathway to the biodegradation of graphene is a very important advance to ensure the safe use of This material at The Graphene Flagship has put research on graphene's effects on health and the environment at the center of its program from the beginning. These results strengthen our innovation and technology roadmap."
Source: https://spa.sciences-world.com/natural-human-enzyme-can-biodegrade-graphene-96683
See also: Master Detox Agent for Graphene Oxide
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