New breakthrough in biomedical field: graphene oxide biodegradable by human enzymes

I. introduction to the structure and properties of graphene

Researchers from the European flagship graphene research project recently explained how a suspension of graphene oxide suspended in water is biodegradable under the catalysis of a human enzyme, and how much of this degradation is related to the colloidal stability of the suspension. This study has great guiding significance for the future application of graphene-based materials in biomedicine.

As with all new materials on the way to industrialisation, the health and safety issues that graphene-based materials can cause have attracted considerable interest from a wide range of experts and the public. The development and commercialization of graphene-based materials is still in its early stages, and the environmental problems, health and safety risks associated with them are still being studied, mainly by researchers involved in the European flagship graphene project. The flagship project is a large international consortium with academic and industrial partnerships, partly funded by the European commission. The aim is primarily to focus on and address the large technological challenges that Europe needs to address through long-term, multidisciplinary research.

The potential health and safety implications of two-dimensional materials, including graphene, are a focus of ongoing research. When it comes to the commercialization of graphene-based materials, their persistence and long-term accumulation in the environment becomes a key issue. Therefore, how to safely dispose of graphene-based materials and other engineering materials has become a very interesting issue. In the case of graphene, this two-dimensional, oxidized form of carbon has great potential for drug release, bionics, tissue engineering, biosensing and other related fields, all due to its high dispersion and biocompatibility in water.

Go materials are highly effective in biomedical technology, but their toxicological effects must also be systematically studied and evaluated. A number of related experimental studies have reported that go materials in some cases can damage living cells and weaken the body's immune response. But taken together, the dates of these experiments are uncertain and, in some cases, contradictory.

Graphene and many of its compounds are biocompatible, but few studies have reported on its degradability. For this reason, a team led by Albert bianco, an expert at the French national research council and one of the researchers behind the flagship project, examined in detail the enzymatic degradation of graphene oxide materials. In their study, published in the journal Small, the researchers showed that myeloperoxidase from human white blood cells, combined with a Small amount of hydrogen peroxide at low concentrations, was able to completely metabolize the highly dispersed graphene oxide samples.

The lead author of the Small study was rajendra akurapati, a postdoctoral student in Bianco's research group. Kurapati and colleagues focused on the ability of myeloperoxidase to degrade three different graphene oxide samples, which were classified according to their dispersion in water. And it's important to note that we're talking about dispersion here, not the concentration of the material. It was found that under the action of myeloperoxidase, the higher the concentration of go suspension, the more difficult it was to degrade, and the more stable colloid could be completely decomposed under the action of enzyme. Chemically, the dispersion of go depends on the oxygen-containing groups on the surface of the graphene material, which in turn affects the biodegradability of the material.

After detailing their results, the researchers began to discuss the mechanism by which go is degraded, starting with a broad overview of how myeloperoxidase targets bacteria and other invasive materials that cause inflammation in biological tissue. During inflammation, neutrophils, a subtype of white blood cell, accumulate in the infected area and secrete myeloperoxidase, which catalyzes the chemical reaction between chloride ions and hydrogen peroxide to produce strong oxidants, such as hypochlorous acid. These oxidants have antibacterial properties and can degrade polyester grafts, extracellular sugars and carbon nanotubes. The authors suggest that the high REDOX potential of these oxidants produced by a chemical reaction catalyzed by myeloperoxidase would degrade the graphene oxide material in suspension in the same way. The places where the material most likely begins to break down are concentrated in the places where carbon atoms combine with oxygen atoms in the graphene lattice. In addition, surface charges have an effect on this process, as in the case of carbon nanotubes. This suggests that the charge makes the go bind more strongly to the enzyme, which then initiates degradation.

"Our experimental study demonstrates that go is completely degraded by myeloperoxidase, and the results also suggest that if people or other organisms accidentally inhale go, the potential health risks can be controlled." Bianco said: "on the other hand, in biomedical applications, the use of graphene-based materials as clinical biomedical materials will also take into account their biodegradability. Our study provides a safe and environmentally sound new method for the treatment of graphene-based materials. "Similarly, this is of great guiding significance for the further development of graphene-based materials as bioactive molecules or release vectors for medical drugs.

The specific mechanism of graphene oxide degradation is still a subject that needs to be further studied and explored, but the latest research results are also obvious. In the presence of hydrogen peroxide, graphene oxide is degraded under the catalysis of myeloperoxidase. Furthermore, the degree of degradation depends on the colloidal stability of the suspension, which suggests that the hydrophilic properties of go are a major factor in its ability to be degraded by myeloperoxidase. Therefore, the stability of the colloids should be taken into account when engineering go materials for biomedical applications.

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