What do butterfly wings, ocean spray, wrinkle-free fabrics and sunscreen have in common? They consist of nanomaterials: particles at an extremely small scale.
Nanomaterials exhibit different characteristics than the same material at a larger size, such as increased strength, chemical reactivity or conductivity. These unique properties open new possibilities in a range of industries, including fashion, healthcare and automotive, where they are becoming an important part of many products.
The characteristics of natural nanomaterials, or those that are a byproduct of industrial processes, are already well understood. But data on the behavior of engineered nanomaterials is more limited. This makes the potential health risks created by those nanomaterials – and the end products in which they are used – extremely complicated to assess.
Nanomaterials interact with the body and its cells in ways that can be difficult to predict. In some cases, it is possible for adverse effects to occur if the particles are inhaled, as their small size can allow them to enter cells and potentially cause damage. Absorption through the skin is not thought to be a risk at present..
While consumers are unlikely to encounter nanomaterials in a form in which inhalation is possible, toxic nanomaterials could pose a risk to those involved in the manufacturing process.
“One of the challenges with assessing nanomaterials is that, because they are so small, they can be quite difficult to manage,” said Dr. Claire Stenkelbery, director general of the Nanotechnology Industries Association. “The characteristics that make them unique, such as higher reactivity, also make them harder to assess, because a nanomaterial will behave differently depending on what you’re doing with it.”
To mitigate their potential for harm, nanomaterials are governed by a strict set of regulations in the European Union. Falling under the EU’s REACH and CLP regulations, those looking to manufacture these materials for use in products sold in the EU need to submit information on their effect on both human health and the environment, and indicate how the potential risk can controlled. As a result of the current complexity of testing nanomaterials, this can be a lengthy and expensive process.
To help streamline toxicity testing, the EU has funded the the SmartNanoTox project through the Horizon 2020 program, a collaboration between academics and industry professionals. The project is developing an approach to screening nanomaterials for toxicity, taking into account the underlying mechanisms that can make them dangerous.
“We want a mechanistic approach from beginning to end,” said Dr. Vladimir Lobaskin, SmartNanoTox project coordinator and associate professor at University College Dublin. “And by mechanistic, we mean that we can track all the events that happen from the initial contact to the adverse outcome. On the biological side, this means tracking adverse outcome pathways, which are the chains of causal events that cause damage to the cells. On the physical chemistry side, this means identifying all the molecular interactions that trigger the biological response. This is not normally done and is the special feature of the project.”
Once this detailed analysis is complete, the data obtained can be used to establish a connection between an adverse outcome pathway and the property that triggers it.
“The advantage of our approach is that it is extensible,” Lobaskin said. “Once we identify the properties of concern, we can then scan new materials for those particular properties. We don’t need to repeat everything, as we can predict similarity by models trained using machine learning algorithms. If we can test a material’s ability to trigger the first event in the pathways we have identified, then our prediction will be that it leads to a damaging outcome.”
Once the pathways are mapped, materials could be grouped according to their ability to trigger specific types of harm. Grouping would make it possible for the toxicity of any new nanomaterial to be predicted with a scan for potentially dangerous properties – a faster and less expensive process than is involved with today’s custom, comprehensive tests.
“What Europe’s trying to do with projects such as SmartNanoTox is enable better early prediction and design of nanomaterials that are going to be safer."Dr. Claire Stenkelbery
Director General of the Nanotechnology Industries Association
For example, one method for a nanomaterial to enter a cell is by adhering to the cell membrane and causing it to bend and wrap around the foreign particle. This is only possible if the adhesion energy is sufficient. By simulating the process, the SmartNanoTox team has created a method to determine the adhesion energies between the membrane and the surface of a nanomaterial, predicting if it is possible for that material to enter a cell.
By developing faster and more efficient classifications, the SmartNanoTox project hopes to give companies looking to use nanomaterials greater confidence during product development.
“What Europe’s trying to do with projects such as SmartNanoTox is enable better early prediction and design of nanomaterials that are going to be safer,” Stenkelbery said. “So rather than getting to the end of a design process, testing it and only then discovering that it’s bad for people, you can predict early in the process. Then you can develop products to market with greater confidence and reduced cost. That would allow products to get to market quicker, which means more potential applications.”
Lobaskin points out that the new approach could also have uses beyond identifying toxicity. Just as it can predict if a nanomaterial will be potentially dangerous, it could also identify characteristics that maximize its usefulness.
“The same approach also works really nicely if you want to enhance functionality,” he said. “What we’re trying to relate is a specific property to a quantifiable outcome. This means that if, for example, you’re trying to deliver drugs to a cell through the use of nanomaterials, we would be able to identify the material that maximizes the amount of the drug that is delivered. So the approach is extensible in that respect as well, as it can be used in the same way to optimize materials and their functionality.”
If successful, the SmartNanoTox project could signal a change in the use of nanomaterials. Freed from the complex and time-consuming process of blanket toxicity testing, businesses can begin to exploit the full potential of their unique properties, with confidence that the products they produce will be both safe and effective.