Nanoparticles serve various industrial and domestic purposes which is reflected in their steadily increasing production volume. This economic success comes along with their presence in the environment and the risk of potentially adverse effects in natural systems. Over the last decade, substantial progress regarding the understanding of sources, fate, and effects of nanoparticles has been made. Predictions of environmental concentrations based on modelling approaches could recently be confirmed by measured concentrations in the field. Nonetheless, analytical techniques are, as covered elsewhere, still under development to more efficiently and reliably characterize and quantify nanoparticles, as well as to detect them in complex environmental matrixes. Simultaneously, the effects of nanoparticles on aquatic and terrestrial systems have received increasing attention. While the debate on the relevance of nanoparticle-released metal ions for their toxicity is still ongoing, it is a re-occurring phenomenon that inert nanoparticles are able to interact with biota through physical pathways such as biological surface coating. This among others interferes with the growth and behaviour of exposed organisms. Moreover, co-occurring contaminants interact with nanoparticles. There is multiple evidence suggesting nanoparticles as a sink for organic and inorganic co-contaminants. On the other hand, in the presence of nanoparticles, repeatedly an elevated effect on the test species induced by the co-contaminants has been reported.
Can We Make Nanoparticles More Sustainable?
Most of us are familiar with the concept of “side effects.” This is when something that is designed to be helpful ends up having some harm that goes along with it. For patients with cancer, anti-cancer drugs can be life-savers – literally. The benefits of using these drugs are apparent to anyone whose cancer has gone into remission thanks to their use. It is well known that these drugs can also have some nasty side effects, yet people still choose to use them because the benefits of being cured outweigh the problems (and of course researchers continue to look for ways to reduce those negative effects). Medicine isn’t the only area where this happens: there are many technologies that have lots of benefits to their use, but can come with some potentially bad side effects. Nanoparticles are one example; they have many amazing uses for consumer products, but they can sometimes have harmful impacts on environmental organisms. One goal of the Center for Sustainable Nanotechnology is to try to find options for designing nanoparticles so that those harmful impacts can be reduced.
One important step toward the goal of designing more environmentally friendly nanoparticles is to figure out how different nanoparticles interact with different organisms in the environment. In order to do this, we investigate the interactions at a molecular level. The goal is to be able to predict interactions and any potential toxicity of nanoparticles with organisms, and then use that knowledge to design nanoparticles in a way that will mitigate environmental risk.
As you can imagine, this is a big goal, with a lot of research to keep track of! A group of researchers in the CSN recently published a paper whose purpose was to summarize what is known about how nanoparticle toxicity works, and to describe ways that nanoparticles could be redesigned to reduce environmental side effects. The three main nanoparticle toxicity mechanisms are:
- nanoparticles binding to the outside of a cell
- nanoparticles dissolving to release toxic ions
- nanoparticles generating harmful reactive oxygen species (ROS)
Since the potential toxicity of a nanoparticle depends both on the nanoparticle type as well as the organism it is interacting with, each of these three types of toxicity can be important in different situations. When redesigning a nanoparticle, scientists first have to identify the main toxicity mechanism, because strategies for reducing toxicity of course will depend on the source of the toxicity. There has been some research done on redesigning nanoparticles, but we hope our paper will inspire more scientists to assess some of the redesign strategies with different nanoparticle models to be able to make better predictions about what will work. Figure 2 gives a quick overview of the multitude of redesign strategies that we talk about in the paper.