Tag Archives: engineered nanoparticles

A debate about engineered nanoparticles and naturally occurring nanoparticles

Thanks to Marina Vance’s Aug. 7, 2015 posting for the Environmental Science: Nano blog I have found an article which constitutes a debate about engineered and naturally occurring nanoparticles (Note: Links have been removed),

Summer is almost over and so is a whirlwind of environmental engineering- and nanotechnology-related conferences. At a previous environmental nanotechnology-related conference, I had the great experience to participate in a lively debate on a very fundamental, albeit not often asked question in our field: is nanotechnology novel?

In this recently published paper, Hochella, Spencer, and Jones present an overview of this unexpected debate. Jones moderated a discussion in which Hochella and Spencer, two experts in their respective fields of nanogeoscience and electrical engineering/material science, brought their arguments for and against the following statement:

“The magic of nanomaterials is not new: nature has been playing these tricks for billions of years.”

The printed debate Vance is referring to was published in Dec. 2014. Here’s a link and a citation,

Nanotechnology: nature’s gift or scientists’ brainchild? by Michael F. Hochella, Jr., Michael G. Spencer, and  Kimberly L. Jones. Environ. Sci.: Nano, 2015,2, 114-119 DOI: 10.1039/C4EN00145A First published online 02 Dec 2014

It is an open access paper.

I thought a few excerpts might be in order,

In the field of environmental nanotechnology, opinions on the novelty of engineered nanomaterials vary; some scientists believe that many engineered nanomaterials are indeed unique, while others are convinced that we are simply fabricating structures already designed in nature. In this article, we present balanced, objective evidence on both sides of the debate. While the idea of novel nanomaterials opens the mind to imagine truly unique structures with architectures unparalleled in nature, the idea that these structures have related analogs in nature has environmental relevance as scientists and engineers aim to design and manufacture more sustainable and environmentally benign nanomaterials.

The ‘there’s nothing new under the sun’ part of the debate (Note: Links have been removed),

For example, the 1996 Nobel Prize in Chemistry was awarded to Robert F. Curl Jr., Sir Harold Kroto, and Richard E. Smalley for the discovery of fullerenes in 1985. Since then, naturally-occurring and “incidental” fullerenes have been found in everything from soot14 to deep space.15,16 It is arguable that fullerenes are present in unimaginable quantities, in every conceivable configuration, throughout the universe.16 And there is a lot of room in our universe (currently measured at 1024 km across) to do it with the full compliment of the periodic table spread throughout. Temperatures and pressures just within our own solar system (not including our sun) range from 3 to 7000 K and from 10−7 to 106 atmospheres pressure. And in the Milky Way alone, there are over 100 billion stars, and roughly that many planets, including a remarkable number of Earth-sized planets orbiting Sun-like stars.17 Yet our galaxy is only one of more than 100 billion galaxies, meaning the number of stars, planets, comets, asteroids, etc. truly defy comprehension. Back here at our infinitesimally small corner of the universe, just on and near Earth’s surface alone, it has been estimated that natural biogeochemical processes produce many thousands of terragrams (1 Tg = 1 million metric tons) of inorganic, organic, and “mixed” nanomaterials per year in a much wider variety than we can possibly presently know (Fig. 1).18 And the naturally-occurring nanomaterials that we have observed to date exhibit an astounding range of variety and complexity.19 In contrast, the current estimates of the annual manmade production of high-tonnage nanomaterials (nano-TiO2; nano-CeO2; carbon nanotubes; fullerenes; nano-Ag) are in the ballpark of hundredth to thousandth of Tg per year,20,21 roughly five to six orders of magnitude less than nature’s bounty, and by comparison, limited in compositional and structural variation.

And, this is the ‘of course, we’re doing something new’ side of the debate (Note: Links have been removed),

This idea can be clearly demonstrated by examining a natural meadow (Fig. 4a) and a garden (Fig. 4b). The meadow is the subject of the scientist who seeks to find out the general physical laws, which underpin the structure and function of the meadow. The engineer can be closely identified with the artist, who in the garden weaves the natural element found in the meadow with powerful effect creating something, which is an amalgamation of nature and man.29 Florman30 summarizes this close relationship between the artist and engineer “But of course we rely upon the artist! He is our cousin, our fellow creator”. Man made nanomaterials distinguish themselves from natural materials through several properties. These properties include order, purity, and scale. These are properties that natural materials often do not have. It is clear that the ability of engineers to fabricate and control nanomaterials is not rivalled by nature.

The summary and implications draws the ideas together,

When determining whether ENMs are truly novel or not, one must realize that we have only just begun to interrogate the Earth’s surface and atmosphere for evidence of these structures, and newly identified, naturally occurring structures are being discovered everyday. At the same time, creative engineers are pushing the limits of discovery to design nanostructures with novel shapes, configurations and properties. At some point, the discovery of naturally-occurring nanomaterials may converge with new ENMs, but in the meantime, scientists and engineers must work together to increase the speed of discovery on both sides of the debate. As we continue to develop nanomaterials for applications, it is important to be aware of natural analogues in order to predict potential environmental and health impacts as well as inform the design and manufacture of nanomaterials with lower likelihood of environmental risks.

I encourage you to read the whole debate if you have the time.

Computer modeling of engineered nanoparticles in surface water, the NanoDUFLOW model

A June 4, 2015 news item on phys.org features research that could be very helpful in understanding the impact that engineered nanoparticles (ENP) have on the water in our environment,

Researchers of Wageningen University (Netherlands) provide the world’s first spatiotemporally explicit model that simulates the behaviour and fate of engineered nanoparticles (ENPs) in surface waters. Wageningen researcher Bart Koelmans: “This is important in order to assure safe nanotechnology. We do need to have an assessment of the risks of ENPs to man and the environment.”

Nanotechnology is developing fast, with the fast growing emission of less than 100 nm engineered nanoparticles as a consequence. ENPs are hard to measure in the environment so that exposure assessments have to rely on modelling. Previous models could only predict average background concentrations on a continental or national scale.

A June 3, 2015 Wageningen University press release, which originated the news item, describes the computer model,

The new NanoDUFLOW model however, developed by Joris Quik, Jeroen de Klein and Bart Koelmans and recently described in Water Research magazine, is capable of simulating the concentrations of ENPs, and their homo- and heteroaggregates in space and time, for any hydrological flow regime of a river. Under the hood of NanoDUFLOW is an ‘engine’ that calculates all relevant interactions among 35 types of particles including the ENPs, and that decides upon aggregation, settling or prolonged flow in the river. The rate of these interactions depends on the flow conditions in the river, which are calculated in the hydrology module of NanoDUFLOW. This module can be set to match the channel structure of any catchment as defined by the user, allowing for a great flexibility.

Development of the model

Development of the model took a long and winding road. ENPs are emerging chemicals with unique properties, which implies that some new process descriptions needed to be developed. One of the main parameters in this new type of models is the attachment efficiency. The attachment efficiency is the chance that two particles stay together when they collide, a chance that depends on the nature of the colliding particles and the chemistry of the water. A smart calculation method needed to be developed that enabled the estimation of the attachment efficiency from laboratory experiments with ENPs and natural particles and waters collected in the field.

Using NanoDUFLOW for the risk assessment of nanomaterials

In order to assure safe nanotechnology, society calls for an assessment of the risks of ENPs to man and the environment. A risk assessment for ENPs requires an assessment of ENP exposure, and of the effects caused by ENPs, which then can be compared in a risk characterisation. Whereas previous screening-level models still may be first choice for lower tiers in the risk assessment, NanoDUFLOW is believed to be useful for higher tiers of the risk assessment, where site specific risks need to be addressed. Simulations with NanoDUFLOW showed the occurrence of clear ENP contamination ‘hot spots’ in the water column and in sediments. Furthermore, NanoDUFLOW was capable of simulating the speciation of ENPs over different size fractions. This speciation defines the ecotoxicologically relevant fractions of ENPs, for a variety of species traits. Also in this respect NanoDUFLOW will add to refining the risk assessment for ENPs.

Here’s a link to and a citation for the paper,

Spatially explicit fate modelling of nanomaterials in natural waters by Joris T. K. Quika, Jeroen J.M. de Klein, & Albert A. Koelmans. Water Research Volume 80, 1 September 2015, Pages 200–208  doi:10.1016/j.watres.2015.05.025

This paper is behind a paywall.

Removing titanium dioxide nanoparticles from water may not be that easy

A March 10, 2015 news item on Nanowerk highlights some research into the removal of nanoscale titanium dioxide particles from water supplies (Note: A link has been removed),

The increased use of engineered nanoparticles (ENMs) in commercial and industrial applications is raising concern over the environmental and health effects of nanoparticles released into the water supply. A timely study that analyzes the ability of typical water pretreatment methods to remove titanium dioxide, the most commonly used ENM, is published in Environmental Engineering Science (“Titanium Dioxide Nanoparticle Removal in Primary Prefiltration Stages of Water Treatment: Role of Coating, Natural Organic Matter, Source Water, and Solution Chemistry”). The article is available free on the Environmental Engineering Science website until April 10, 2015.

A March 10, 2015 Mary Ann Liebert, Inc., publishers news release (also on EurekAlert), which originated the news item, provides more details about the work (Note: A link has been removed),

Nichola Kinsinger, Ryan Honda, Valerie Keene, and Sharon Walker, University of California, Riverside, suggest that current methods of water prefiltration treatment cannot adequately remove titanium dioxide ENMs. They describe the results of scaled-down tests to evaluate the effectiveness of three traditional methods—coagulation, flocculation, and sedimentation—in the article “Titanium Dioxide Nanoparticle Removal in Primary Prefiltration Stages of Water Treatment: Role of Coating, Natural Organic Matter, Source Water, and Solution Chemistry.”

“As nanoscience and engineering allow us to develop new exciting products, we must be ever mindful of associated consequences of these advances,” says Domenico Grasso, PhD, PE, DEE, Editor-in-Chief of Environmental Engineering Science and Provost, University of Delaware. “Professor Walker and her team have presented an excellent report raising concerns that some engineered nanomaterials may find their ways into our water supplies.”

“While further optimization of such treatment processes may allow for improved removal efficiencies, this study illustrates the challenges that we must be prepared to face with the emergence of new engineered nanomaterials,” says Sharon Walker, PhD, Professor of Chemical and Environmental Engineering, University of California, Riverside.

Here’s a link to and a citation for the paper,

Titanium Dioxide Nanoparticle Removal in Primary Prefiltration Stages of Water Treatment: Role of Coating, Natural Organic Matter, Source Water, and Solution Chemistry by Nichola Kinsinger, Ryan Honda, Valerie Keene, and Sharon L. Walker. Environmental Engineering Science. doi:10.1089/ees.2014.0288.

This paper is freely available until April 10, 2015.

Interestingly Sharon Walker and Nichola Kinsinger recently co-authored a paper (mentioned in my March 9, 2015 post) about copper nanoparticles and water treatment which concluded this about copper nanoparticles in water supplies,

The researchers found that the copper nanoparticles, when studied outside the septic tank, impacted zebrafish embryo hatching rates at concentrations as low as 0.5 parts per million. However, when the copper nanoparticles were released into the replica septic tank, which included liquids that simulated human digested food and household wastewater, they were not bioavailable and didn’t impact hatching rates.

Taking these these two paper into account (and the many others I’ve read), there is no simple or universal answer to the question of whether or not ENPs or ENMs are going to pose environmental problems.

New method for measuring risks and quantities of engineered nanomaterials delivered to cells

Despite all the talk about testing engineered nanoparticles and their possible effects on cells, there are problems with the testing process which researchers at the Harvard School of Public Health (HSPH) claim to have addressed (h/t Nanowerk, March 28, 2014).

A March 28, 2014 HSPH press release explains the interest in testing the effects of engineered nanomaterials/nanoparticles on health and describes some of the problems associated with testing their interaction with cells,

Thousands of consumer products containing engineered nanoparticles — microscopic particles found in everyday items from cosmetics and clothing to building materials — enter the market every year. Concerns about possible environmental health and safety issues of these nano-enabled products continue to grow with scientists struggling to come up with fast, cheap, and easy-to-use cellular screening systems to determine possible hazards of vast libraries of engineered nanomaterials. However, determining how much exposure to engineered nanoparticles could be unsafe for humans requires precise knowledge of the amount (dose) of nanomaterials interacting with cells and tissues such as lungs and skin.

With chemicals, this is easy to do but when it comes to nanoparticles suspended in physiological media, this is not trivial. Engineered nanoparticles in biological media interact with serum proteins and form larger agglomerates which alter both their so called effective density and active surface area and ultimately define their delivery to cell dose and bio-interactions. This behavior has tremendous implications not only in measuring the exact amount of nanomaterials interacting with cells and tissue but also in defining hazard rankings of various engineered nanomaterials (ENMs). As a result, thousands of published cellular screening assays are difficult to interpret and use for risk assessment purposes.

The press release goes on to describe the new technique (Note: Links have been removed),

Scientists at the Center for Nanotechnology and Nanotoxicology at Harvard School of Public Health (HSPH) have discovered a fast, simple, and inexpensive method to measure the effective density of engineered nanoparticles in physiological fluids, thereby making it possible to accurately determine the amount of nanomaterials that come into contact with cells and tissue in culture.

The method, referred to as the Volumetric Centrifugation Method (VCM), was published in the March 28, 2014 Nature Communications.

The new discovery will have a major impact on the hazard assessment of engineered nanoparticles, enabling risk assessors to perform accurate hazard rankings of nanomaterials using cellular systems. Furthermore, by measuring the composition of nanomaterial agglomerates in physiologic fluids, it will allow scientists to design more effective nano-based drug delivery systems for nanomedicine applications.

“The biggest challenge we have in assessing possible health effects associated with nano exposures is deciding when something is hazardous and when it is not, based on the dose level. At low levels, the risks are probably miniscule,” said senior author Philip Demokritou, associate professor of aerosol physics in the Department of Environmental Health at HSPH. “The question is: At what dose level does nano-exposure become problematic? The same question applies to nano-based drugs when we test their efficiency using cellular systems. How much of the administered nano-drug will come in contact with cells and tissue? This will determine the effective dose needed for a given cellular response,” Demokritou said.

Federal regulatory agencies do not require manufacturers to test engineered nanoparticles, if the original form of the bulk material has already been shown to be safe. However, there is evidence that some of these materials could be more harmful in the nanoscale — a scale at which materials may penetrate cells and bypass biological barriers more easily and exhibit unique physical, chemical, and biological properties compared to larger size particles. Nanotoxicologists are struggling to develop fast and cheap toxicological screening cellular assays to cope with the influx of vast forms of engineered nanomaterials and avoid laborious and expensive animal testing. However, this effort has been held back due to the lack of a simple-to-use, fast, method to measure the dose-response relationships and possible toxicological implications. While biological responses are fairly easy to measure, scientists are struggling to develop a fast method to assess the exact amount or dose of nanomaterials coming in contact with cells in biological media.

“Dosimetric considerations are too complicated to consider in nano-bio assessments, but too important to ignore,” Demokritou said. “Comparisons of biological responses to nano-exposures usually rely on guesstimates based on properties measured in the dry powder form (e.g., mass, surface area, and density), without taking into account particle-particle and particle-fluid interactions in biological media. When suspended in fluids, nanoparticles typically form agglomerates that include large amounts of the suspending fluid, and that therefore have effective densities much lower than that of dry material. This greatly influences the particle delivery to cells, and reduces the surface area available for interactions with cells,” said Glen DeLoid, research associate in the Department of Environmental Health, one of the two lead authors of the study. “The VCM method will help nanobiologists and regulators to resolve conflicting in vitro cellular toxicity data that have been reported in the literature for various nanomaterials. These disparities likely result from lack of or inaccurate dosimetric considerations in nano-bio interactions in a cellular screening system,” said Joel Cohen, doctoral student at HSPH and one of the two lead authors of the study.

Here’s a link to and a citation for the paper,

Estimating the effective density of engineered nanomaterials for in vitro dosimetry by Glen DeLoid, Joel M. Cohen, Tom Darrah, Raymond Derk, Liying Rojanasakul, Georgios Pyrgiotakis, Wendel Wohlleben, & Philip Demokritou. Nature Communications 5, Article number: 3514 doi:10.1038/ncomms4514 Published 28 March 2014

This paper is behind a paywall but a free preview is available via ReadCube Access.

Inaugural workshop using *nanomaterials for environmental remediation being held in Louisiana

Participants at the Nano-4-Rem (nanomaterials for environmental remediation) aNsseRS workshop will be visiting the Southeastern Louisiana University in Hammond in early June 2013. From the Nov.  6, 2012 news item on Nanowerk,

An inaugural workshop on the safe use of nanomaterials in environmental remediation will be held at Southeastern Louisiana University June 5-7, 2013.

With increased use of nanotechnology and nanomaterials in the cleanup of hazardous sites, there is now a growing body of evidence that exposure to these materials may have adverse health effects, said conference organizer Ephraim Massawe, assistant professor of occupational safety, health and environment.

“The applications and results of nano-enabled strategies and methods for environmental remediation are increasingly promising,” Massawe said. “The challenge is ensuring that such applications are both safe and sustainable.”

There is more information on Southeastern Louisiana University’s Nano-4-Rem aNsseRS webpage,

Background: Groundwater or soil contamination is present at most Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA) and Resource Conservation and Recovery Act (RCRA) corrective action sites. Traditional technologies, such as pump-and-treat (P&T) and permeable reactive barriers (PRBs), have been used for decades to remediate such sites. In recent years, remediation strategies involving engineered nanoparticles (ENPs) such as zero-valent iron and titanium dioxide have been demonstrated as viable time-saving and cost-effective alternatives to traditional remediation. In addition, advances in nanotechnology-enabled assessment and monitoring methods such as nano-sensors may support more extensive, reliable, and cost effective assessment and management of remediation activities.

At the same time that applications of nano-enabled strategies and methods for environmental remediation are increasingly promising, there is a growing body of evidence linking exposure to certain nanomaterials with adverse health effects in animals at the laboratory scale. The challenge is to ensure that such applications are both safe and sustainable. …

Workshop Objectives: This is the first national workshop that provides an opportunity for representatives from the environmental remediation community, industry, academia, and government to:

  • Share their perspectives, pose questions, and develop ideas for design of good guidelines, selection criteria, and work practices to support safe and sustainable nano-enabled environmental remediation;
  • Become acquainted with other U.S. nanotechnology stakeholders, including vendors, transporters, and contractors of the remediation sites and communities; and
  • Share case studies of nano-enhanced clean up technologies, including selection criteria for alternative remediation strategies and methods, job planning, job tasks, and nanomaterial handling practices.

Furthermore, in the context of nanoinformatics (Nanoinformatics 2020 Roadmap), the workshop will present:

  • Occupational and environmental regulatory issues as they relate to remediation, synthesis and characterization, and application of nanoinformatics for safe and sustainable use of nanomaterials during remediation;
  • Fate and transport of nanomaterials during and after remediation;
  • Risks, including contributions from both toxicological properties of nanomaterials (hazard) and potentials for occupational and environmental exposure, where hazard x exposure = risk;
  • Results of the recent nanoinformatics survey of state agencies and programs described on the workshop website; and
  • Opportunities for developing and sustaining continuing advances and collaborations.

Call for Presenters and Deadlines: Participants are invited from the industry; site contractors, nanomaterial vendors; laboratories that synthesize and characterize ENPs for environmental remediation; regulatory authorities (local, state, and federal government) and academia (faculty and students). Presenters should submit titles and abstracts for podium or poster presentations by December 14, 2012. The workshop or program schedule will be finalized by February 20, 2013. Event date: June 5-7, 2013. Students are encouraged to submit proposals for podium or poster presentations. “Best student” poster and presentation awards will be given. Information about this workshop can also be found at http://cluin.org [a US Environmental Protection Agency ‘office’].

The Nov. 7, 2012 news release from Southeastern Louisiana University which originated the news item (Nanowerk seems to have posted the item before the release was posted on the university website) provides more detail,

The event, “Nano-4-Rem-Anssers 2013: Applications of Nanotechnology for Safe and Sustainable Environmental Remediations,” is one of the first of its kind in the Southeast which has been designed to provide an opportunity for involved parties to share perspectives, pose questions and develop ideas for generating solid guidelines for best work practices that support safe and sustainable nano-enabled environmental remediation.

Southeastern is sponsoring the event with other agencies and institutions, including the U.S. Environmental Protection Agency (EPA), the National Institute of Safety and Health (NIOSH), the Occupational Safety and Health Administration (OSHA) and in conjunction with the National Nanotechnology Coordination Office (NNCO).

The program will include case studies of nano-enhanced clean up technologies, including selection criteria for alternative remediation strategies and methods, job planning and tasks, and safe material handling practices. Other issues to be discussed are updates of toxicity studies, fate and transport of nanoparticules [the French word for nanoparticles is nanoparticules ..  this seems an unusual choice for a news release from a US university but Louisiana was French at one time, so perhaps there’s a desire to retain a linguistic link?]  in soils and groundwater, and nanoinformatics.

I have written about nanoremediation before. Here are a few of the latest,

Nanoremediation techniques from Iran and from South Carolina

Canadian soil remediation expert in Australia

Phyto and nano soil remediation (part 2: nano)

* ‘nanotechnolmaterials corrected to ‘nanomaterials’ on Sept. 23, 2013.