Graphene oxide (GO) is a nanomaterial derived from graphite, consisting of a single layer of carbon atoms arranged in a hexagonal lattice but functionalized with oxygen-containing groups like hydroxyl, epoxy, and carboxyl groups. This modification makes the material highly dispersible in water, leading to its extensive use in technology and biomedical research. GO is being explored for applications such as drug delivery systems, biosensors, and composite materials. This analysis explores the current scientific understanding of how graphene oxide interacts with the human body and the biological consequences of that interaction.
Routes of Human Exposure to Graphene Oxide
Human exposure to graphene oxide can occur through several distinct pathways, largely dictated by its application in industrial or medical settings. A primary concern is inhalation, which mainly affects workers in manufacturing facilities where GO is produced or handled in powdered or aerosolized forms. Airborne GO particles can enter the respiratory system, posing a risk to lung tissue. Ingestion is another pathway, which could theoretically occur through the consumption of contaminated water or food. Dermal contact is also a possibility, particularly in occupational environments, where the material may come into contact with skin, leading to potential absorption.
The most direct route of exposure is injection, which is relevant in the context of biomedical applications where GO nanosheets are engineered for use as drug carriers or imaging agents. In these therapeutic applications, the material is intentionally introduced into the body, often directly into the bloodstream.
Cellular Mechanisms of Graphene Oxide Toxicity
Once inside the body, graphene oxide interacts with cells and tissues through several molecular mechanisms that can ultimately lead to adverse effects. The most frequently observed mechanism is the induction of oxidative stress, which involves the excessive generation of reactive oxygen species (ROS) within the cell. These highly reactive molecules overwhelm the cell’s natural antioxidant defenses, leading to damage of cellular components, including lipids, proteins, and DNA, resulting in lipid peroxidation and genotoxicity. The physical structure of GO can also cause mechanical damage to cellular structures, particularly the cell membrane. The edges of the nanosheets can disrupt the lipid bilayer, causing a loss of integrity and cell leakage.
GO exposure also disrupts mitochondrial function, interfering with the production of adenosine triphosphate (ATP), the cell’s primary energy source. This energy depletion and physical damage activate signaling pathways that trigger programmed cell death, or apoptosis. Furthermore, GO initiates an inflammatory response, as cells recognize the nanomaterial as a foreign threat and release signaling molecules that recruit immune cells.
Documented and Potential Adverse Health Outcomes
The cellular mechanisms of damage translate into specific adverse outcomes across various physiological systems, primarily observed in in vitro studies and animal models. In the pulmonary system, inhalation exposure can trigger significant inflammation within the lungs. This response can lead to the formation of granulomas and potentially to pulmonary fibrosis, a condition involving the scarring of lung tissue. GO particles travel from the entry point and accumulate in filtering organs such as the liver, spleen, and kidneys.
This accumulation can cause organ stress and has been linked to signs of tissue damage, particularly with prolonged exposure. In the circulatory system, GO can interact with blood components, promoting platelet aggregation, which raises concerns about the risk of thrombosis or blood clot formation. The material’s presence can also induce cardiotoxicity, demonstrated by damage to myocardial tissues in animal studies. Systemic consequences of GO exposure include chronic inflammation and immune system alteration.