Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

When nano may not be nano

15.09.2009
The same properties of nanoparticles that make them so appealing to manufacturers may also have negative effects on the environment and human health.

However, little is known which particles may be harmful. Part of the problem is determining exactly what a nanoparticle is.

A new analysis by an international team of researchers from the Center for the Environmental Implications of NanoTechnology (CEINT), based at Duke University, argues for a new look at the way nanoparticles are selected when studying the potential impacts on human health and the environment. They have found that while many small particles are considered to be "nano," these materials often do not meet full definition of having special properties that make them different from conventional materials.

Under the prevailing definition, a particle is deemed nano if its diameter is between 1 and 100 nanometers (nm) – about 1/10,000 the diameter of a human hair – and if it has properties that significantly differ from its naturally occurring, or bulk, counterpart.

The special properties of nanoparticles come from their high surface-area-to-volume ratio. They also have a considerably higher percentage of atoms on their surface compared to bulk particles, which can make them more reactive. These man-made materials can be found in a vast array of consumer products, including paints and sunscreens, as well as in water treatment plants and drug delivery systems.

For most of this decade, discussions of nanoparticles have tended to focus more on their size than their properties. However, after reviewing the scientific literature, the Duke-led team believes that the old definition is not specific enough. A definition that focuses on properties is critical, they say, to help scientists determine which particular nanoparticles are the most likely to represent a threat to the environment or human health.

Generally speaking, it is the very smallest particles (less than 30 nanometers) that should receive the most attention in studying the environmental and human health impacts of nanomaterials, according to Mark Wiesner, a Duke professor of civil and environmental engineering and director of the federally funded CEINT.

"There are an infinite number of potential new man-made nanoparticles, so we need to find a way to narrow our efforts to those that have the greatest likelihood of having the unique properties with unique effects," Wiesner said.

"A key question to be answered is whether or not a particular nanoparticle has toxic or hazardous properties that are truly different from identical particles in their bulk form," Wiesner continued. "This question has not been answered. To do so, we need to be speaking the same language when assessing any unique properties of these novel materials."

The results of Wiesner's analysis were published online in the journal Nature Nanotechnology. The study was supported by CEINT, which is jointly funded by the National Science Foundation and Environmental Protection Agency.

Specifically, the researchers found that nanoparticles approaching the 100 nm end of the size spectrum tend to have fewer special properties when compared to their bulk counterparts. Furthermore, they found that nanoparticles smaller than 30 nm tend to exhibit the unique properties that should command increased scrutiny, Wiesner said.

"Many nanoparticles smaller than 30 nanometers undergo drastic changes in their crystalline structure that enhance how the atoms on their surface interact with the environment," Wiesner said.

For example, because of the increased surface-area-to-volume ratio, nanoparticles can be highly reactive with other chemicals in the environment and can also disrupt certain activities within cells.

"While there have been reports of nanoparticle toxicity increasing as the size decreases, it is still uncertain whether this increase in reactivity is harmful to the environment or human safety," Wiesner said. "To settle this issue, toxicological studies should contrast particles that exhibit novel size-dependant properties, particularly concerning their surface reactivity, and those particles that do not exhibit these properties."

Other members of the research team include Melanie Auffan, Duke; Jerome Rose and Jean-Yves Bottero, Aix-Marseille Universite, France; Gregory Lowry, Carnegie Mellon University; and Jean-Pierre Jolivet, Laboratoire de Chimie de la Matiere Condensee de Paris, France.

Richard Merritt | EurekAlert!
Further information:
http://www.duke.edu

More articles from Materials Sciences:

nachricht One in 5 materials chemistry papers may be wrong, study suggests
15.12.2017 | Georgia Institute of Technology

nachricht Scientists channel graphene to understand filtration and ion transport into cells
11.12.2017 | National Institute of Standards and Technology (NIST)

All articles from Materials Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: First-of-its-kind chemical oscillator offers new level of molecular control

DNA molecules that follow specific instructions could offer more precise molecular control of synthetic chemical systems, a discovery that opens the door for engineers to create molecular machines with new and complex behaviors.

Researchers have created chemical amplifiers and a chemical oscillator using a systematic method that has the potential to embed sophisticated circuit...

Im Focus: Long-lived storage of a photonic qubit for worldwide teleportation

MPQ scientists achieve long storage times for photonic quantum bits which break the lower bound for direct teleportation in a global quantum network.

Concerning the development of quantum memories for the realization of global quantum networks, scientists of the Quantum Dynamics Division led by Professor...

Im Focus: Electromagnetic water cloak eliminates drag and wake

Detailed calculations show water cloaks are feasible with today's technology

Researchers have developed a water cloaking concept based on electromagnetic forces that could eliminate an object's wake, greatly reducing its drag while...

Im Focus: Scientists channel graphene to understand filtration and ion transport into cells

Tiny pores at a cell's entryway act as miniature bouncers, letting in some electrically charged atoms--ions--but blocking others. Operating as exquisitely sensitive filters, these "ion channels" play a critical role in biological functions such as muscle contraction and the firing of brain cells.

To rapidly transport the right ions through the cell membrane, the tiny channels rely on a complex interplay between the ions and surrounding molecules,...

Im Focus: Towards data storage at the single molecule level

The miniaturization of the current technology of storage media is hindered by fundamental limits of quantum mechanics. A new approach consists in using so-called spin-crossover molecules as the smallest possible storage unit. Similar to normal hard drives, these special molecules can save information via their magnetic state. A research team from Kiel University has now managed to successfully place a new class of spin-crossover molecules onto a surface and to improve the molecule’s storage capacity. The storage density of conventional hard drives could therefore theoretically be increased by more than one hundred fold. The study has been published in the scientific journal Nano Letters.

Over the past few years, the building blocks of storage media have gotten ever smaller. But further miniaturization of the current technology is hindered by...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

See, understand and experience the work of the future

11.12.2017 | Event News

Innovative strategies to tackle parasitic worms

08.12.2017 | Event News

AKL’18: The opportunities and challenges of digitalization in the laser industry

07.12.2017 | Event News

 
Latest News

Engineers program tiny robots to move, think like insects

15.12.2017 | Power and Electrical Engineering

One in 5 materials chemistry papers may be wrong, study suggests

15.12.2017 | Materials Sciences

New antbird species discovered in Peru by LSU ornithologists

15.12.2017 | Life Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>