Graphene oxide is a derivative of graphene, a single layer of carbon atoms arranged in a hexagonal lattice. This material possesses distinct properties, including a high surface area, strength, and electrical conductivity. Its unique characteristics have led to interest in understanding its presence and implications within human biological systems.
What Graphene Oxide Is
Graphene oxide is an oxidized form of graphene, a two-dimensional carbon compound. Its structure includes oxygen-containing functional groups like hydroxyl, epoxy, and carboxyl groups, attached to the basal plane and edges of its carbon layers. These functional groups make graphene oxide easily dispersible in water and other polar solvents.
These oxygen functionalities enable chemical modification and influence how graphene oxide interacts with biological systems. Graphene oxide also exhibits nanoscale dimensions and a high surface-to-volume ratio, contributing to its unique surface properties and ability to adsorb various substances. Its properties, including conductivity, can be modulated by controlling the type and number of these oxygen-containing functional groups.
Routes of Exposure and Entry
Graphene oxide can enter the human body through several pathways. Inhalation is a primary route, particularly in occupational settings like manufacturing or research, where airborne particles might be present. The lungs are at particular risk from airborne graphene oxide exposure.
Dermal contact is another potential route, especially if the skin has cuts or abrasions. Accidental ingestion is also a possible pathway. Graphene oxide can also be intentionally introduced for medical purposes, such as drug delivery or diagnostic imaging.
Interactions Within the Body
Once in the body, graphene oxide undergoes various interactions and distribution. It can travel through the bloodstream and accumulate in different organs, including the liver, spleen, lungs, and kidneys. Its distribution depends on factors like particle size, shape, and surface properties.
Cells can internalize graphene oxide particles, a process influenced by the material’s surface characteristics. Proteins can adsorb onto the surface of graphene oxide, forming a “protein corona.” This protein layer alters the material’s biological behavior, affecting its cellular uptake and subsequent interactions. Graphene oxide can also trigger biological responses such as oxidative stress, inflammatory reactions, and influence cell viability and function.
Emerging Medical Applications
Graphene oxide’s properties make it a promising material for various biomedical applications. It is explored for drug delivery systems, acting as a carrier for targeted delivery of drugs, genes, and vaccines.
Graphene oxide also finds application in biosensors and diagnostics, enabling detection of biomarkers. Its optical and electrical properties make it suitable for bioimaging techniques, functioning as a contrast agent. In tissue engineering, graphene oxide serves as a scaffold material to support cell growth and regeneration, leveraging its biocompatibility and mechanical strength.
Current Understanding of Human Safety
Research regarding the safety of graphene oxide in humans is ongoing and complex. The safety profile is influenced by several factors, including the particle’s size, shape, surface functionalization, concentration, and the route of exposure. For instance, surface modifications can enhance biocompatibility and reduce adverse effects.
In vitro (cell culture) and in vivo (animal) studies have provided insights into its biological compatibility, degradation, and clearance from the body. Some studies suggest that concentrations below 20 μg/mL may be non-toxic to human fibroblasts, while higher concentrations, such as 50 μg/mL, can show significant toxicity to cells. Animal studies have also indicated that at doses exceeding 0.4 mg, graphene oxide can accumulate in organs like the lungs, liver, spleen, and kidneys, potentially leading to adverse effects. Regulatory guidelines are still being developed, emphasizing the need for comprehensive safety assessments before widespread human application, as its use in humans remains largely experimental and requires rigorous evaluation for long-term safety.