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by Nishad Karim
August 23,
2018
from
Graphene-Flagship Website
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This visualization shows
layers of graphene used for membranes.
Credit:
University of Manchester
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Natural Human Enzyme
can Biodegrade Graphene,
scientists report...
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Degradation of pristine
graphene occurs in the human body when interacting with a naturally
occurring enzyme found in the lung, announced
Graphene Flagship
partners:
Graphene based products,
including flexible biomedical electronic devices, are being
designed for interface with the human body within the Graphene
Flagship.
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If graphene is to be used
for such biomedical applications, it should be biodegradable and
thus be expelled from the body.
To test how graphene behaves within the body, Alberto Bianco
and his team at Graphene Flagship partner
CNRS conducted
several tests to determine whether and how graphene was broken down
with the addition of a common human enzyme.
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The enzyme,
myeloperoxidase (MPO), is a peroxide enzyme released by
neutrophils,
cells found in the lungs that are responsible for the elimination of
foreign bodies or bacteria that enter the body.
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If a foreign body or
bacteria is detected inside of the body, neutrophils surround it and
secrete MPO, thereby destroying the threat.
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Previous work by Graphene
Flagship partners found,
MPO to biodegrade graphene oxide...
However
the structure of non-functionalized graphene was thought to be more
degradation resistant.
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To test this, Bianco and
his team looked at the effects of MPO, ex-vivo, on two graphene
forms:
single- and few-layer...
Bianco says,
"We used two forms of
graphene, single- and few-layer, prepared by two different
methods in water.
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They were then taken
and put in contact with myeloperoxidase in the presence of
hydrogen peroxide. This peroxidase was able to degrade and
oxidize them.
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This was not really
expected, because we thought that non-functionalized graphene
was more resistant than graphene oxide."
Rajendra Kurapati,
first author on the study, from Graphene Flagship partner CNRS,
said,
"The results
emphasize that highly dispersible graphene could be degraded in
the body by the action of neutrophils.
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This would open the
new avenue for developing graphene-based materials."
In-vivo testing is the
next stage...
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Bengt Fadeel,
professor at Graphene Flagship partner
Karolinska Institute,
says,
"Understanding
whether graphene is biodegradable or not is important for
biomedical and other applications of this material.
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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 topic, because in
principle, graphene dispersed in the atmosphere could produce
some harm.
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Instead, if there are
microorganisms able to degrade graphene and related materials,
the persistence of these materials in our environment will be
strongly decreased.
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These types of
studies are needed.
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What is also needed is to investigate the
nature of degradation products. Once graphene is digested by
enzymes, it could produce harmful derivatives.
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We need to know the
structure of these derivatives and study their impact on health
and environment."
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.
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The Graphene Flagship
has put the investigation of the health and environment effects
of graphene at the centre of its program since the start.
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These results
strengthen our innovation and technology roadmap."
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Additional Information
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Rajendra
Kurapati et al. - Degradation of Single-Layer and Few-Layer Graphene by Neutrophil Myeloperoxidase
- Angewandte Chemie
International Edition (2018).
DOI: 10.1002/anie.201806906
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Rajendra
Kurapati et al. - Dispersibility-Dependent Biodegradation of
Graphene Oxide by Myeloperoxidase - Small (2015).
DOI: 10.1002/smll.201500038
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Sourav P.
Mukherjee et al. - Graphene oxide is degraded by neutrophils
and the degradation products are non-genotoxic -� Nanoscale
(2017).
DOI: 10.1039/c7nr03552g
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