The Biodegradability of 2D Materials: A Key to Safer NanotechnologyIf you are interested in products related to the research phase in this field, please contact for further inquiries.
Two-dimensional (2D) materials, characterized by their atomic thickness and unique physicochemical properties, have garnered significant attention across various scientific disciplines. These materials, including graphene, transition metal dichalcogenides (TMDs), and hexagonal boron nitride (hBN), offer unparalleled advantages in electronics, energy storage, and biomedical applications. However, the increasing use of 2D materials necessitates a thorough understanding of their biodegradability to ensure environmental and biological safety.
Biodegradability refers to the natural breakdown of materials into non-toxic by-products, a critical factor for sustainable and safe applications. For 2D materials, this involves studying their interactions with biological systems and environmental conditions. The degradation process can be influenced by the material's chemical composition, surface functionalization, and the presence of specific enzymes or oxidizing agents.
Fig 1. Molecular structures of representative 2D materials. (Ma B., et al., 2020) 
Graphene, a single layer of carbon atoms, has been extensively studied for its exceptional mechanical, electrical, and thermal properties. However, its biodegradability is a crucial aspect for its safe application in biomedical and environmental contexts. Recent studies have shown that pristine graphene can be partially degraded by oxidative enzymes such as myeloperoxidase (MPO) and horseradish peroxidase (HRP), which catalyze the oxidation of graphene in the presence of hydrogen peroxide (H₂O₂). This process introduces defects and functional groups onto the graphene surface, facilitating further degradation.
Graphene oxide (GO), a derivative with a higher oxygen content, exhibits enhanced biodegradability due to its increased reactivity. Chemical functionalization of GO with molecules like catechol and coumarin has been shown to improve its interaction with peroxidases, leading to faster degradation rates. This "degradation-by-design" approach not only enhances the biodegradability of graphene materials but also opens up new possibilities for their biomedical applications.
Transition metal dichalcogenides (TMDs), such as molybdenum disulfide (MoS₂) and tungsten disulfide (WS₂), are another class of 2D materials with promising applications in optoelectronics and biomedicine. These materials exhibit unique electronic and optical properties due to their tunable bandgap, making them suitable for various applications. However, their biodegradability is a critical factor for their safe use.
MoS₂ has been shown to degrade in oxidative environments, particularly in the presence of peroxidases like MPO. The degradation process involves the oxidation of MoS₂ into soluble molybdenum oxide species, which can be safely excreted from biological systems. Functionalization of MoS₂ with poly(acrylic acid) (PAA) has been demonstrated to enhance its stability and biodegradability in physiological conditions, making it a promising candidate for biomedical applications.
Hexagonal boron nitride (hBN), known for its high mechanical stiffness and thermal conductivity, has shown resistance to oxidative degradation. However, recent studies have demonstrated that hBN can be partially degraded by MPO and completely degraded by photo-Fenton reactions. The degradation process involves the oxidation of hBN into soluble boron-containing species.
Despite its chemical stability, hBN has shown potential for biomedical applications due to its biocompatibility and non-toxicity. Functionalization of hBN with specific molecules can enhance its biodegradability and interaction with biological systems, opening up new opportunities for its use in tissue engineering and drug delivery.
Xenes, including phosphorene and silicene, are emerging 2D materials with unique electronic properties and potential for biomedical applications. Phosphorene, in particular, has shown high biodegradability, degrading into phosphate ions in the presence of oxygen and water. This property makes phosphorene a promising material for drug delivery and tissue engineering.
Functionalization of phosphorene with aryl diazonium salts has been shown to reduce its degradation rate, highlighting the importance of surface modification in tuning the biodegradability of Xenes. The biodegradability of these materials ensures their safe elimination from biological systems, making them suitable for various biomedical applications.
The biodegradability of 2D materials opens up a range of potential biomedical applications, including drug delivery, cancer therapy, tissue engineering, and bioelectronics. Biodegradable 2D materials like GO and phosphorene have been explored as carriers for drug delivery, encapsulating drugs and releasing them at the target site before degrading into non-toxic by-products.
In cancer therapy, 2D materials have shown promise in photothermal therapy (PTT) and chemodynamic therapy (CDT). For example, MoS₂ and phosphorene have been used as photothermal agents to kill cancer cells under near-infrared (NIR) light irradiation. Additionally, MnO₂ nanosheets have been explored for CDT, where they react with intracellular glutathione (GSH) to generate reactive oxygen species (ROS) that cause cancer cell death.
Biodegradable 2D materials have also been used in tissue engineering, where they can be employed as scaffolds to support cell growth and tissue regeneration. For instance, a self-supporting graphene hydrogel film has been shown to stimulate osteogenic differentiation of stem cells and promote bone tissue regeneration. The biodegradability of these materials ensures that they can be safely eliminated from the body after serving their purpose.
The biodegradability of 2D materials is a crucial factor in determining their safety and potential applications in biomedicine. Chemical functionalization offers a powerful strategy to enhance the biodegradability of these materials, enabling the development of safer and more effective nanomaterials. As research in this field continues to advance, we can expect to see the development of new biodegradable 2D materials with tailored properties for a wide range of biomedical applications.
The future of 2D materials in biomedicine looks promising, with the potential to revolutionize drug delivery, cancer therapy, and tissue engineering. By understanding the biodegradability of 2D materials and leveraging chemical functionalization, we can design safer and more effective nanomaterials for a wide range of biomedical applications. The development of biodegradable 2D materials is not only essential for environmental sustainability but also for the advancement of medical technologies that can improve human health and well-being.
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This article is for research use only and cannot be used for any clinical purposes.
