Nav: Home

Nanoparticles remain unpredictable

April 19, 2017

The nanotech industry is booming. Every year, several thousands of tonnes of man-made nanoparticles are produced worldwide; sooner or later, a certain part of them will end up in bodies of water or soil. But even experts find it difficult to say exactly what happens to them there. It is a complex question, not only because there are many different types of man-made (engineered) nanoparticles, but also because the particles behave differently in the environment depending on the prevailing conditions.

Researchers led by Martin Scheringer, Senior Scientist at the Department of Chemistry and Applied Biosciences, wanted to bring some clarity to this issue. They reviewed 270 scientific studies, and the nearly 1,000 laboratory experiments described in them, looking for patterns in the behaviour of engineered nanoparticles. The goal was to make universal predictions about the behaviour of the particles.

Particles attach themselves to everything

However, the researchers found a very mixed picture when they looked at the data. "The situation is more complex than many scientists would previously have predicted," says Scheringer. "We need to recognise that we can't draw a uniform picture with the data available to us today."

Nicole Sani-Kast, a doctoral student in Scheringer's group and first author of the analysis published in the journal PNAS, adds: "Engineered nanoparticles behave very dynamically and are highly reactive. They attach themselves to everything they find: to other nanoparticles in order to form agglomerates, or to other molecules present in the environment."

Network analysis

To what exactly the particles react, and how quickly, depends on various factors such as the acidity of the water or soil, the concentration of the existing minerals and salts, and above all, the composition of the organic substances dissolved in the water or present in the soil. The fact that the engineered nanoparticles often have a surface coating makes things even more complicated. Depending on the environmental conditions, the particles retain or lose their coating, which in turn influences their reaction behaviour.

To evaluate the results available in the literature, Sani-Kast used a network analysis for the first time in this research field. It is a technique familiar in social research for measuring networks of social relations, and allowed her to show that the data available on engineered nanoparticles is inconsistent, insufficiently diverse and poorly structured.

More method for machine learning

"If more structured, consistent and sufficiently diverse data were available, it may be possible to discover universal patterns using machine learning methods," says Scheringer, "but we're not there yet." Enough structured experimental data must first be available.

"In order for the scientific community to carry out such experiments in a systematic and standardised manner, some kind of coordination is necessary," adds Sani-Kast, but she is aware that such work is difficult to coordinate. Scientists are generally well known for preferring to explore new methods and conditions rather than routinely performing standardized experiments.


Distinguishing man-made and natural nanoparticles

In addition to the lack of systematic research, there is also a second tangible problem in researching the behaviour of engineered nanoparticles: many engineered nanoparticles consist of chemical compounds that occur naturally in the soil. So far it has been difficult to measure the engineered particles in the environment since it is hard to distinguish them from naturally occurring particles with the same chemical composition.

However, researchers at ETH Zurich's Department of Chemistry and Applied Biosciences, under the direction of ETH Professor Detlef Günther, have recently established an effective method that makes such a distinction possible in routine investigations. They used a state-of-the-art and highly sensitive mass spectrometry technique (called spICP-TOF mass spectrometry) to determine which chemical elements make up individual nanoparticles in a sample.

In collaboration with scientists from the University of Vienna, the ETH researchers applied the method to soil samples with natural cerium-containing particles, into which they mixed engineered cerium dioxide nanoparticles. Using machine learning methods, which were ideally suited to this particular issue, the researchers were able to identify differences in the chemical fingerprints of the two particle classes. "While artificially produced nanoparticles often consist of a single compound, natural nanoparticles usually still contain a number of additional chemical elements," explains Alexander Gundlach-Graham, a postdoc in Günther's group.

The new measuring method is very sensitive: the scientists were able to measure engineered particles in samples with up to one hundred times more natural particles.



Sani-Kast N, Labille J, Ollivier P, Slomberg D, Hungerbühler K, Scheringer M: A network perspective reveals decreasing material diversity in studies on nanoparticle interactions with dissolved organic matter. PNAS 2017, 114: E1756-E1765, doi: 10.1073/pnas.1608106114 []

Praetorius A, Gundlach-Graham A, Goldberg E, Fabienke W, Navratilova J, Gondikas A, Kaegi R, Günther D, Hofmann T, von der Kammer F: Single-particle multi-element fingerprinting (spMEF) using inductively-coupled plasma time-of-flight mass spectrometry (ICP-TOFMS) to identify engineered nanoparticles against the elevated natural background in soils. Environmental Science: Nano 2017, 4: 307-314, doi: 10.1039/c6en00455e []

ETH Zurich

Related Nanoparticles Articles:

Chemists perform surgery on nanoparticles
A team of chemists led by Carnegie Mellon's Rongchao Jin has for the first time conducted site-specific surgery on a nanoparticle.
Nanoparticles remain unpredictable
The way that nanoparticles behave in the environment is extremely complex.
Gold standards for nanoparticles
KAUST researchers reveal how small organic 'citrate' ions can stabilize gold nanoparticles, assisting research on the structures' potential.
Lipid nanoparticles for gene therapy
Twenty-five years have passed since the publication of the first work on solid lipid nanoparticles (SLNs) and nanostructured lipid carriers (NLCs) as a system for delivering drugs.
Nanoparticles hitchhiking their way along strands of hair
In shampoo ads, hair always looks like a shiny, smooth surface.
Better contrast agents based on nanoparticles
Scientists at the University of Basel have developed nanoparticles which can serve as efficient contrast agents for magnetic resonance imaging.
Gentle cancer treatment using nanoparticles works
Cancer treatments based on laser irridation of tiny nanoparticles that are injected directly into the cancer tumor are working and can destroy the cancer from within.
Radiation-guided nanoparticles zero in on metastatic cancer
Zap a tumor with radiation to trigger expression of a molecule, then attack that molecule with a drug-loaded nanoparticle.
Nanoparticles can grow in cubic shape
Use of nanoparticles in many applications, e.g. for catalysis, relies on the surface area of the particles.
Nanoparticles deliver anticancer cluster bombs
Scientists have devised a triple-stage 'cluster bomb' system for delivering the chemotherapy drug cisplatin, via tiny nanoparticles designed to break up when they reach a tumor.

Best Science Podcasts 2017

We have hand picked the best science podcasts for 2017. Sit back and enjoy new science podcasts updated daily from your favorite science news services and scientists.
Now Playing: Radiolab

Oliver Sipple
One morning, Oliver Sipple went out for a walk. A couple hours later, to his own surprise, he saved the life of the President of the United States. But in the days that followed, Sipple's split-second act of heroism turned into a rationale for making his personal life into political opportunity. What happens next makes us wonder what a moment, or a movement, or a whole society can demand of one person. And how much is too much?
Now Playing: TED Radio Hour

Future Consequences
From data collection to gene editing to AI, what we once considered science fiction is now becoming reality. This hour, TED speakers explore the future consequences of our present actions. Guests include designer Anab Jain, futurist Juan Enriquez, biologist Paul Knoepfler, and neuroscientist and philosopher Sam Harris.