Tag Archives: ENP

Using sugar for a better way to clean nanoparticles from organisms

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Researchers at the US National Institute of Standards and Technology (NIST) have found that a laboratory technique used for over 60 years is the best way to date to clean nanoparticles from organisms. From a Jan. 26, 2017 news item on ScienceDaily,

Sometimes old-school methods provide the best ways of studying cutting-edge tech and its effects on the modern world.

Giving a 65-year-old laboratory technique a new role, researchers at the National Institute of Standards and Technology (NIST) have performed the cleanest separation to date of synthetic nanoparticles from a living organism. The new NIST method is expected to significantly improve experiments looking at the potential environmental and health impacts of these manufactured entities. It will allow scientists to more accurately count how many nanoparticles have actually been ingested by organisms exposed to them.

A Jan. 26, 2017 NIST news release (also on EurekAlert), which originated the news item, offers more detail,

The common roundworm Caenorhabditis elegans has been used in recent years as a living model for laboratory studies of how biological and chemical compounds may affect multicellular organisms. These compounds include engineered nanoparticles (ENPs), bits of material between 1 and 100 nanometers (billionths of a meter, or about 1/10,000 the diameter of a red blood cell). Previous research has often focused on quantifying the amount and size of engineered nanoparticles ingested by C. elegans. Measuring the nanoparticles that actually make it into an organism is considered a more relevant indicator of potential toxicity than just the amount of ENPs to which the worms are exposed.

Traditional methods for counting ingested ENPs have produced questionable results. Currently, researchers expose C. elegans to metal ENPs such as silver or gold in solution, then rinse the excess particles away with water followed by centrifugation and freeze-drying. A portion of the “cleaned” sample produced is then typically examined by a technique that determines the amount of metal present, known as inductively coupled plasma mass spectrometry (ICP-MS). It often yields ENP counts in the tens of thousands per worm; however, those numbers always seem too high to NIST researchers working with C. elegans.

“Since ICP-MS will detect all of the nanoparticles associated with the worms, both those ingested and those that remain attached externally, we suspect that the latter is what makes the ‘ENPs’ per-worm counts so high,” said NIST analytical chemist Monique Johnson (link sends e-mail), the lead author on the ACS Nano paper. “Since we only wanted to quantify the ingested ENPs, a more robust and reliable separation method was needed.”

Luckily, the solution to the problem was already in the lab.

Cross section of the roundworm C. elegans

Scanning electron micrograph showing a cross section of the roundworm C. elegans with two ingested engineered nanoparticles (red dots just right of center). Images such as this provided NIST researchers with visual confirmation that nanoparticle consumption actually occurred. Credit: K. Scott/NIST

In the course of culturing C. elegans for ENP-exposure experiments, Johnson and her colleagues had used sucrose density gradient centrifugation, a decades-old and established system for cleanly separating cellular components, to isolate the worms from debris and bacteria. “We wondered if the same process would allow us to perform an organism-from-ENP separation as well, so I designed a study to find out,” Johnson said.

In their experiment, the NIST researchers first exposed separate samples of C. elegans to low and high concentrations of two sizes of gold nanospheres, 30 and 60 nanometers in diameter. The researchers put each of the samples into a centrifuge and removed the supernatant (liquid portion), leaving the worms and ENPs in the remaining pellets. These were centrifuged twice in a salt solution (rather than just water as in previous separation methods), and then centrifuged again, but this time, through a uniquely designed sucrose density gradient.

“From top to bottom, our gradient consisted of a salt solution layer to trap excess ENPs and three increasingly dense layers of sucrose [20, 40 and 50 percent] to isolate the C. elegans,” Johnson explained. “We followed up the gradient with three water rinses and with centrifugations to ensure that only worms with ingested ENPs, and not the sucrose separation medium with any excess ENPs, would make it into the final pellet.”

Analyzing the range of masses in the ultrapurified samples indicated gold levels more in line with what the researchers expected would be found as ingested ENPs. Experimental validation of the NIST separation method’s success came when the worms were examined in detail under a scanning electron microscope (SEM).

“For me, the eureka moment was when I first saw gold ENPs in the cross section images taken from the C. elegans samples that had been processed through the sucrose density gradient,” Johnson said. “I had been dreaming about finding ENPs in the worm’s digestive tract and now they were really there!”

The high-resolution SEM images also provided visual evidence that only ingested ENPs were counted. “No ENPs were attached to the cuticle, the exoskeleton of C. elegans, in any of the sucrose density gradient samples,” Johnson said. “When we examined worms from our control experiments [processed using the traditional no-gradient, water-rinse-only separation method], there were a number of nanospheres found attached to the cuticle.

Now that it has been successfully demonstrated, the NIST researchers plan to refine and further validate their system for evaluating the uptake of ENPs by C. elegans. “Hopefully, our method will become a useful and valuable tool for reducing the measurement variability and sampling bias that can plague environmental nanotoxicology studies,” Johnson said.

They’ve tested this technique on gold nanoparticles, which begs the question, What kinds of nanoparticles can this technique be used for? Metal nanoparticles only or all nanoparticles?

I’m sure the researchers have already asked these questions and started researching the answers. While the rest of us wait, here’s a link to and a citation for the paper about this promising new technique,

Separation, Sizing, and Quantitation of Engineered Nanoparticles in an Organism Model Using Inductively Coupled Plasma Mass Spectrometry and Image Analysis by Monique E. Johnson, Shannon K. Hanna, Antonio R. Montoro Bustos, Christopher M. Sims, Lindsay C. C. Elliott, Akshay Lingayat, Adrian C. Johnston, Babak Nikoobakht, John T. Elliott, R. David Holbrook, Keana C. K. Scott, Karen E. Murphy, Elijah J. Petersen, Lee L. Yu, and Bryant C. Nelson. ACS Nano, 2017, 11 (1), pp 526–540 DOI: 10.1021/acsnano.6b06582 Publication Date (Web): December 16, 2016

Copyright This article not subject to U.S. Copyright. Published 2016 by the American Chemical Society

This paper is behind a paywall.

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

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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.

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

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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.