Tag Archives: titanium dioxide

Combining bacteriorhodopsin with semiconducting nanoparticles to generate hydrogen

Scientists at the US Argonne National Laboratory have created a hybrid bio-assisted photocatalyst according to a July 19, 2013 news item on ScienceDaily,

A protein found in the membranes of ancient microorganisms that live in desert salt flats could offer a new way of using sunlight to generate environmentally friendly hydrogen fuel, according to a new study by researchers at the U.S. Department of Energy’s Argonne National Laboratory.

Argonne nanoscientist Elena Rozhkova and her colleagues combined a pigment called bacteriorhodopsin with semiconducting nanoparticles to create a system that uses light to spark a catalytic process that creates hydrogen fuel.

Before getting to the new hybrid the story starts with nano titanium dioxide (from the July 16, 2013 Argonne National Laboratory press release, which originated the news item),

Scientists have been aware of the potential of titanium dioxide nanoparticles for light-based reactions since the early 1970s, when Japanese researchers discovered that a titanium dioxide electrode exposed to bright ultraviolet light could split water molecules in a phenomenon that came to be known as the Honda-Fujishima effect. Since then, scientists have made continuous efforts to extend the light reactivity of titanium dioxide photocatalysts into the visible part of the spectrum. The promise of these photocatalysts prompted scientists to experiment with different modifications to their basic chemistry in hope of making the reaction more efficient, Rozhkova said.

“Titanium dioxide alone reacts with ultraviolet light, but not with visible light, so we used biological photoreactive molecules as a building block to create a hybrid system that could use visible light efficiently,” Rozhkova said.

Rozhkova and her colleagues turned to bacteriorhodopsin – which is responsible for the unusual purple color of a number of salt flats in California and Nevada – because it uses sunlight as an energy source that allows it to act as a “proton pump.”  Proton pumps are proteins that typically straddle a cellular membrane and transfer protons from inside the cell to the extracellular space.

Here’s an image of the purple membrane caused by bacteriorhodopsin (from University of Bari [Italy] Professor Angela Correlli’s webpage of Photorecptors and Olfactory Receptors,

Bacteriorhodopsin is the only protein of purple membranes, which contains few different lipids. [downloaded from the University of Bari: http://www.biologia.uniba.it/fisiologia/corcelli/en/ric2.html]

Bacteriorhodopsin is the only protein of purple membranes, which contains few different lipids. [downloaded from the University of Bari: http://www.biologia.uniba.it/fisiologia/corcelli/en/ric2.html]

The press release goes on to describe the hybrid system,

In the Argonne system, the protons provided by the bacteriorhodopsin are combined with free electrons at small platinum sites interspersed in the titanium dioxide matrix. “The platinum nanoparticles are essential for creating a distinct spot for the production of the hydrogen molecule,” said Peng Wang, an Argonne postdoctoral researcher in Rozhkova’s group at Argonne’s Center for Nanoscale Materials.

“It is interesting that in biology, bacteriorhodopsin does not naturally participate in these kind of reactions,” Rozhkova said. “Its natural function really doesn’t have much to do at all with creating hydrogen. But as part of this hybrid, it helps make hydrogen under white light and at environmentally friendly conditions.”

This bio-assisted hybrid photocatalyst outperforms many other similar systems in hydrogen generation and could be a good candidate for fabrication of green energy devices that consume virtually infinite sources — salt water and sunlight.

You can find the published paper with the link below,

High-Performance Bioassisted Nanophotocatalyst for Hydrogen Production by Shankar Balasubramanian, Peng Wang, Richard D. Schaller, Tijana Rajh, and Elena A. Rozhkova. Nano Lett., 2013, 13 (7), pp 3365–3371 DOI: 10.1021/nl4016655 Publication Date (Web): June 19, 2013
Copyright © 2013 American Chemical Society

The paper is behind a paywall.

*The head for this posting was corrected from Combining bacteriorhodopsin with semiconduction nanopartcles to generate hydrogen to Combining bacteriorhodopsin with semiconductor nanoparticles to generate hydrogen on July 22, 2013 at 3:03 pm PDT.

** I changed the head for this posting again from ‘semiconductor’ to ‘semiconducting’ on July 23, 2013 at 6:50 am PDT.

You probably can’t poison yourself by eating too many nanoparticles

Researchers, Ingrid Bergin in the Unit for Laboratory Animal Medicine, at the University of Michigan in Ann Arbor and Frank Witzmann in the Department of Cellular and Integrative Physiology, at Indiana University School of Medicine, in Indianapolis, have stated that ingesting food and beverage (translated by me from the more scientific description) with nanoparticles (at today’s current levels) is unlikely to prove toxic. A June 26, 2013 Inderscience news release on EurekAlert describes the researchers’ research and their conclusions,

Writing in a forthcoming issue of the International Journal of Biomedical Nanoscience and Nanotechnology, researchers have compared existing laboratory and experimental animal studies pertaining to the toxicity of nanoparticles most likely to be intentionally or accidentally ingested. Based on their review, the researchers determined ingestion of nanoparticles at likely exposure levels is unlikely to cause health problems, at least with respect to acute toxicity. Furthermore, in vitro laboratory testing, which often shows toxicity at a cellular level, does not correspond well with in vivo testing, which tends to show less adverse effects.

Ingrid Bergin in the Unit for Laboratory Animal Medicine, at the University of Michigan in Ann Arbor and Frank Witzmann in the Department of Cellular and Integrative Physiology, at Indiana University School of Medicine, in Indianapolis, explain that the use of particles that are in the nano size range (from 1 billionth to 100 billionths of a meter in diameter, 1-100 nm, other thereabouts) are finding applications in consumer products and medicine. These include particles such as nano-silver, which is increasingly used in consumer products and dietary supplements for its purported antimicrobial properties. Nanoparticles can have some intriguing and useful properties because they do not necessarily behave in the same chemical and physical ways as non-nanoparticle versions of the same material.

Nanoparticles are now used as natural flavor enhancers in the form of liposomes and related materials, food pigments and in some so-called “health supplements”. They are also used in antibacterial toothbrushes coated with silver nanoparticles, for instance in food and drink containers and in hygienic infant feeding equipment. They are also used to carry pharmaceuticals to specific disease sites in the body to reduce side effects. Nanoparticles actually encompass a very wide range of materials from pure metals and alloys, to metal oxide nanoparticles, and carbon-based and plastic nanoparticles. Because of their increasing utilization in consumer products, there has been concern over whether these small scale materials could have unique toxicity effects when compared to more traditional versions of the same materials.

Difficulties in assessing the health risks of nanoparticles include the fact that particles of differing materials and shapes can have different properties. Furthermore, the route of exposure (e.g. ingestion vs. inhalation) affects the likelihood of toxicity. The U.S. researchers evaluated the current literature specifically with respect to toxicity of ingested nanoparticles. They point out that, in addition to intentional ingestion as with dietary supplements, unintentional ingestion can occur due to nanoparticle presence in water or as a breakdown product from coated consumer goods. Inhaled nanoparticles also represent an ingestion hazard since they are coughed up, swallowed, and eliminated through the intestinal tract.

Based on their review, the team concludes that, “Ingested nanoparticles appear unlikely to have acute or severe toxic effects at typical levels of exposure.” Nevertheless, they add that the current literature is inadequate to assess whether nanoparticles can accumulate in tissues and have long-term effects or whether they might cause subtle alterations in gut microbial populations. The researchers stress that better methods are needed for correlating particle concentrations used for cell-based assessment of toxicity with the actual likely exposure levels to body cells. Such methods may lead to better predictive value for laboratory in vitro testing, which currently over-predicts toxicity of ingested nanoparticles as compared to in vivo testing.

The researchers focused specifically on ingestion via the gastrointestinal tract which I take to mean that they focused largely on nanoparticles in food (eaten) and liquid (swallowed).

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

Nanoparticle toxicity by the gastrointestinal route: evidence and knowledge gaps by Ingrid L. Bergin; Frank A. Witzmann.  Int. J. of Biomedical Nanoscience and Nanotechnology, 2013 Vol.3, No.1/2, pp.163 – 210.  DOI: 10.1504/IJBNN.2013.054515

I think the abstract further helps to understand the research focus,

The increasing interest in nanoparticles for advanced technologies, consumer products, and biomedical applications has led to great excitement about potential benefits but also concern over the potential for adverse human health effects. The gastrointestinal tract represents a likely route of entry for many nanomaterials, both directly through intentional ingestion or indirectly via nanoparticle dissolution from food containers or by secondary ingestion of inhaled particles. Additionally, increased utilisation of nanoparticles may lead to increased environmental contamination and unintentional ingestion via water, food animals, or fish. The gastrointestinal tract is a site of complex, symbiotic interactions between host cells and the resident microbiome. Accordingly, evaluation of nanoparticles must take into consideration not only absorption and extraintestinal organ accumulation but also the potential for altered gut microbes and the effects of this perturbation on the host. The existing literature was evaluated for evidence of toxicity based on these considerations. Focus was placed on three categories of nanomaterials: nanometals and metal oxides, carbon-based nanoparticles, and polymer/dendrimers with emphasis on those particles of greatest relevance to gastrointestinal exposures.

The article is behind a paywall.

I last mentioned Frank Witzmann here in a May 8, 2013 posting titled, US multicenter (Nano GO Consortium) study of engineered nanomaterial toxicology.

Self-cleaning products dangerous?

For anyone else out there who hates housecleaning, this is heartbreaking research. Personally, I’m not sure I can ever forgive Professor Jonathan Raff at Indian University for this (from a June 12, 2103 Indiana University news release; also on EurekAlert),

Research by Indiana University [IU] environmental scientists shows that air-pollution-removal technology used in “self-cleaning” paints and building surfaces may actually cause more problems than they solve.

The study finds that titanium dioxide coatings, seen as promising for their role in breaking down airborne pollutants on contact, are likely in real-world conditions to convert abundant ammonia to nitrogen oxide, the key precursor of harmful ozone pollution.

“As air quality standards become more stringent, people are going to be thinking about other technologies that can reduce pollution,” said Jonathan D. Raff, assistant professor in the School of Public and Environmental Affairs at IU Bloomington and an author of the study. “Our research suggests that this may not be one of them.”

Here’s a link to and a citation for this published study,

Photooxidation of Ammonia on TiO2 as a Source of NO and NO2 under Atmospheric Conditions by Mulu A. Kebede, Mychel E. Varner ‡, Nicole K. Scharko, R. Benny Gerber, and Jonathan D. Raff. J. Am. Chem. Soc., 2013, 135 (23), pp 8606–8615 DOI: 10.1021/ja401846x Publication Date (Web): May 30, 2013

Copyright © 2013 American Chemical Society

This research is behind a paywall.

The news release goes on to explain what makes this latest discovery about titanium dioxide particularly relevant,

The findings are timely because the Environmental Protection Agency is developing stricter regulations for ground-level ozone, a primary component in photochemical smog. The pollution is linked to serious health problems, including breathing difficulties and heart and lung disease.

Ozone is produced by reactions involving nitrogen oxides (NOx), which come primarily from motor vehicle emissions, and volatile organic compounds resulting from industrial processes. Equipping cars with catalytic converters has been effective at reducing ozone in urban areas. But different technologies may be needed to meet tighter air-quality standards of the future.

The need has sparked interest in titanium dioxide, a common mineral that is used as a whitening agent in paints and surface coatings. The compound acts as a photocatalyst, breaking down nitrogen oxides, ammonia and other pollutants in the presence of sunlight. “Self-cleaning” surfaces coated with titanium dioxide can break down chemical grime that will otherwise adhere to urban buildings. News stories have celebrated “smog-eating” tiles and concrete surfaces coated with the compound.

But Raff and his colleagues show that, in normal environmental conditions, titanium dioxide also catalyzes the incomplete breakdown of ammonia into nitrogen oxides. Ammonia is an abundant constituent in motor vehicle emissions, and its conversion to nitrogen oxides could result in increases in harmful ozone concentrations.

“We show that uptake of atmospheric NH3 (ammonia) onto surfaces containing TiO2 (titanium dioxide) is not a permanent removal process, as previously thought, but rather a photochemical route for generating reactive oxides of nitrogen that play a role in air pollution and are associated with significant health effects,” the authors write.

Raff, who is also an adjunct professor of chemistry in the IU College of Arts and Sciences, said other studies missed the effect on ammonia because they investigated reactions that occur with high levels of emissions under industrial conditions, not the low levels and actual humidity levels typically present in urban environments.

The findings also call into question other suggestions for using titanium dioxide for environmental remediation — for example, to remove odor-causing organic compounds from emissions produced by confined livestock feeding operations. Titanium dioxide has also been suggested as a geo-engineering substance that could be injected into the upper atmosphere to reflect sunlight away from the Earth and combat global warming.

Further studies in Raff’s lab are aimed at producing better understanding of the molecular processes involved when titanium dioxide catalyzes the breakdown of ammonia. The results could suggest approaches for developing more effective pollution-control equipment as well as improvements in industrial processes involving ammonia.

It’ll be interesting to see how that resolves itself. I imagine some of the civil society groups are going to get very excited about this research.

US multicenter (Nano GO Consortium) study of engineered nanomaterial toxicology

Nano Go Consortium is the name they gave a multicenter toxicology study of engineered nanomaterials which has pioneered a new approach  in the US to toxicology research. From the May 6, 2013 news item on Azonano,

For the first time, researchers from institutions around the country have conducted an identical series of toxicology tests evaluating lung-related health impacts associated with widely used engineered nanomaterials (ENMs).

The study [on rodents] provides comparable health risk data from multiple labs, which should help regulators develop policies to protect workers and consumers who come into contact with ENMs.

The May 6, 2013 North Carolina State University news release, which originated the news item, describes the results from one of two studies that were recently published by the Nano GO Consortium in Environmental Health Perspectives,

The researchers found that carbon nanotubes, which are used in everything from bicycle frames to high performance electronics, produced inflammation and inflammatory lesions in the lower portions of the lung. However, the researchers found that the nanotubes could be made less hazardous if treated to remove excess metal catalysts used in the manufacturing process or modified by adding carboxyl groups to the outer shell of the tubes to make them more easily dispersed in biological fluids.

The researchers also found that titanium dioxide nanoparticles also caused inflammation in the lower regions of the lung. Belt-shaped titanium nanoparticles caused more cellular damage in the lungs, and more pronounced lesions, than spherical nanoparticles.

Here’s a link to and a citation for this study on rodents,

Interlaboratory Evaluation of Rodent Pulmonary Responses to Engineered Nanomaterials: The NIEHS NanoGo Consortium by James C. Bonner, Rona M. Silva, Alexia J. Taylor, Jared M. Brown, Susana C. Hilderbrand, Vincent Castranova, Dale Porter, Alison Elder, Günter Oberdörster, Jack R. Harkema, Lori A. Bramble, Terrance J. Kavanagh, Dianne Botta, Andre Nel, and Kent E. Pinkerton. Environ Health Perspect (): .doi:10.1289/ehp.1205693  Published: May 06, 2013

And the information for the other study which this consortium has published,

Interlaboratory Evaluation of in Vitro Cytotoxicity and Inflammatory Responses to Engineered Nanomaterials: The NIEHS NanoGo Consortium by Tian Xia, Raymond F. Hamilton Jr, James C. Bonner, Edward D. Crandall, Alison Elder, Farnoosh Fazlollahi, Teri A. Girtsman, Kwang Kim, Somenath Mitra, Susana A. Ntim, Galya Orr, Mani Tagmount8, Alexia J. Taylor, Donatello Telesca, Ana Tolic, Christopher D. Vulpe, Andrea J. Walker, Xiang Wang, Frank A. Witzmann, Nianqiang Wu, Yumei Xie, Jeffery I. Zink, Andre Nel, and Andrij Holian. Environ Health Perspect (): .doi:10.1289/ehp.1306561 Published: May 06, 2013

Environmental Health Perspectives is an open access journal and the two studies are being offered as ‘early’ publication efforts and will be updated with the full studies at a later date.

Most interesting for me is the editorial offered by four of the researchers involved in the Nano GO Consortium, from the editorial,

Determining the health effects of ENMs presents some unique challenges. The thousands of ENMs in use today are made from an enormous range of substances, vary considerably in size, and take a diversity of shapes, including spheres, cubes, cones, tubes, and other forms. They are also produced in different laboratories across the world using a variety of methods. In the scientific literature, findings on the properties and toxicity of these materials are mixed and often difficult to compare across studies. To improve the reliability and reproducibility of data in this area, there is a need for uniform research protocols and methods, handling guidelines, procurement systems, and models.

Although there is still much to learn about the toxicity of ENMs, we are fortunate to start with a clean slate: There are as yet no documented incidences of human disease due to ENM exposure (Xia et al. 2009). Because ENMs are manmade rather than natural substances, we have an opportunity to design, manufacture, and use these materials in ways that allow us to reap the maximum benefits—and minimal risk—to humans.

With $13 million from the American Recovery and Reinvestment Act (2009), the National Institute of Environmental Health Sciences (NIEHS) awarded 13 2-year grants to advance research on the health impacts of ENMs (NIEHS 2013). [emphasis mine] Ten grants were awarded through the National Institutes of Health (NIH) Grand Opportunities program and three were funded through the NIH Challenge Grants program. One goal of this investment was to develop reliable, reproducible methods to assess exposure and biological response to nanomaterials.

Within the framework of the consortium, grantees designed and conducted a series of “round-robin” experiments in which similar or identical methods were used to perform in vitro and in vivo tests on the toxicity of selected nanomaterials concurrently at 13 different laboratories.

Conducting experiments in a round-robin format within a consortium structure is an unfamiliar approach for most researchers. Although some researchers acknowledged that working collaboratively with such a large and diverse group at times stretched the limits of their comfort zones, the consortium ultimately proved to be “greater than the sum of its parts,” resulting in reliable, standardized protocols that would have been difficult for researchers to achieve by working independently. Indeed, many participants reflected that participating in the consortium not only benefitted their shared goals but also enhanced their individual research efforts. The round-robin approach and the overall consortium structure may be valuable models for other emerging areas of science.

Here’s a link to and a citation for the Consortium’s editorial, which is available in full,

Nano GO Consortium—A Team Science Approach to Assess Engineered Nanomaterials: Reliable Assays and Methods by Thaddeus T. Schug, Srikanth S. Nadadur, and Anne F. Johnson. Environ Health Perspect 121(2013). http://dx.doi.org/10.1289/ehp.1306866 [online 06 May 2013]

I like the idea of researchers working together across institutional and geographical boundaries as that can be a very powerful approach. I hope that won’t devolve into a form of institutionalized oppression where individual researchers are forced out or ignored. In general, it’s the outlier research that often proves to be truly groundbreaking, which often generates extraordinary and informal (and sometimes formal) resistance. For an example of groundbreaking work that was rejected by other researchers who banded together informally, there’s Dan Shechtman, 2011 Nobel Laureate in Chemistry, famously faced hostility from his colleagues for years over his discovery of quasicrystals.

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.

Toxicology convo heats up: OECD releases report on inhalation toxicity testing and Nature Nanotechnology publishes severe critique of silver toxicity overanalysis

This has to be one of the rawest reports I’ve seen and that’s not a criticism. The OECD (Organization for Economic Cooperation and Development) has released no. 35 in its Series on the Safety of Manufactured Nanomaterials titled, INHALATION TOXICITY TESTING: EXPERT MEETING ON POTENTIAL REVISIONS TO OECD TEST GUIDELINES AND GUIDANCE DOCUMENT.

This report is the outcome of a meeting which took place in fall 2011 according to the July 4, 2012 news item on Nanowerk,

The expert meeting on Inhalation Toxicity Testing for Nanomaterials was held on 19-20 October 2011 in The Hague, hosted by the Netherlands, with the aim of discussing the results of the OECD Sponsorship Programme (under the responsibility of SG3) on this specific topic and addressing issues relevant to inhalation toxicity. Fifty experts from the WPMN as well as the OECD Working Group of the National Coordinators for the Test Guidelines programme (WNT) participated in the meeting.

This is a partial list of recommendations from the report,

Recommendations raised by the speakers for the discussion

7. Various recommendations were raised by the speakers that served as points for discussion. These recommendations do not necessarily reflect a general agreement. …

• “Provide explicit guidance for the generation of aerosols (sample preparation) based on the exposure scenario”. Hans Muijser

• “Generation of a test atmosphere should have workplace characteristics, but should be adapted to adjust for rodent respirability”. Günter Oberdörster

• “A choice for a dry aerosol or a liquid aerosol should depend on the given test substance and planned test approach (hazard- or risk driven)”. Otto Creutzenberg

• “Aerosol characterization should include size distribution, mass, number and morphology of the material”. Günter Oberdörster

• “Mass concentration is not sufficient for comparison of nanomaterials of the same chemical composition”. Flemming Cassee

• “Dry powders will appear as agglomerate upon aerosolization, which needs to be addressed in the sample preparation guidelines”. Flemming Cassee

• “Dissolution behaviour of the test substance should be assessed in physiological fluids mimicking various lung-specific pH ambiences (neutral, acid)”. Otto Creutzenberg

• “Data analysis should include interpretation of aerosol characteristics, NOAEL, risk assessment implications, mode of action and a strategy for dosimetric extrapolation to humans. The inclusion of biokinetic data is important”. Günter Oberdörster

• “Include biokinetics in the guidance, since different distribution patterns in the whole organism are likely dependent on physicochemical characteristics of nanoparticle aerosols and the dose at the target site will therefore be different. This will allow the assessment of accumulation of nanomaterials in the body at low exposure levels and long-term exposure. A way to perform it is by radiolabelled materials, chemical elemental analysis to determine organ concentrations and transmission electron microscopy”. Wolfgang Kreyling. Others who have suggested inclusion of biokinetics or recognized the importance were Otto Creutzenberg, Frieke Kuper, Günter Oberdörster and David Warheit. (p. 13)

You actually see who made the recommendations! Speakers discussed carbon nanotubes, titanium dioxide, cerium oxide, zinc oxide and more, all of which you can read about in summary form in this 38 pp. report.

Meanwhile, Nature Nanotechnology has published an incendiary commentary about nanosilver and the latest request by the European Commission for another study.  Michael Berger has devoted a July 4, 2012 Nanowerk Spotlight article to the commentary,

A commentary by Steffen Foss Hansen and Anders Baun in this week’s Nature Nanotechnology (“When enough is enough”  [behind a paywall]) pointedly asks “when will governments and regulatory agencies stop asking for more reports and reviews, and start taking regulatory action?”

Hansen and Baun, both from the Technical University of Denmark’s Department of Environmental Engineering, take issue with yet another scientific opinion on nanosilver that has been requested by the European Commission in late 2011: “SCENIHR – Request for a scientific opinion on Nanosilver: safety, health and environmental effects and role in antimicrobial resistance” (pdf). Specifically, the EC wants SCENIHR to answer four questions under the general heading of ‘Nanosilver: safety, health and environmental effects, and role in antimicrobial resistance’.

“Most of these questions – and possibly all of them – have already been addressed by no less than 18 review articles in scientific journals, the oldest dating back to 2008, plus at least seven more reviews and reports commissioned and/or funded by governments and other organizations” Hansen tells Nanowerk. “Many of these reviews and reports go through the same literature, cover the same ground and identify many of the same data gaps and research needs.”

Here’s a prediction from Hansen and Baun as to what will be in the next report due in 2013  (from the Nature Nanotechnology commentary When enough is enough in 7, 409–411 (2012) published online  July 1, 2012 [Note: I have removed links and footnotes]),

… we predict that the SCENIHR’s upcoming review will consist of five main sections summarizing: the properties and uses of nanosilver; human and environmental toxicity; microbial resistance; risk assessment; and research needs. We also predict that the SCENIHR’s report will say something along the following lines: “Nanosilver is reportedly one of the most widely used nanomaterials in consumer products today but the scale of production and use is unknown. The antibacterial properties of nanosilver are exploited in a very diverse set of products and applications including dietary supplements, personal care products, powdered colours, textile, paper, kitchenware and food storage.” And like many previous reviews and reports, the new report is likely to cite the Consumer Product Inventory maintained by the Project on Emerging Nanotechnologies.

We acknowledge that answering the question of how to regulate the use of nanosilver is not easy given the different views of the different stakeholders in this debate and the complex regulatory landscape associated with the many applications of nanosilver. …

Arguably, we all want that the pros and cons of regulatory policy options be based on the best available science while taking broader socio-economical and ethical aspects into consideration before deciding on the appropriate regulatory measures concerning human and environmental exposure to nanosilver. Although it is common for independent scientific experts to be commissioned to gather, analyse and review the available scientific information, and to provide recommendations on how to address a given risk, we do not see the need for further reviews. It is time for the European Commission to decide on the regulatory measures that are appropriate for nanosilver. These measures should then be implemented wholeheartedly and their effectiveness monitored.

I predict this commentary will provoke some interesting responses and I will try to add the ones I can find to this posting as they become available.

ETA July 6, 2012: Dexter Johnson weighed in with his July 5, 2012 posting (Note: I have removed a link),

What may make the matter even worse is that we may already have a pretty substantial framework—in the US, at least—on which to base nanosilver regulations, which dates back to the 1950s. It concerned what was called at the time collodial silver, which is essentially what today is called nanosilver.

But getting back to current stagnant state of affairs, it’s hard to know exactly what’s causing the paralysis. It could be concern over implementing regulations in a depressed economy, or just a fear of taking a position. But in both these instances, the lack of action is making the situation worse. …

Butterflies give and give; this time they inspire more green fuel production

Butterflies are proving to be quite generous as they inspire ideas for greater production of green fuels in addition to everything else they’ve inspired. From the March 26, 2012 news item on Nanowerk,

“We were searching the ‘art of blackness’ for the secret of how those black wings [from black butterflies] absorb so much sunlight and reflect so little,” Fan [Tongxiang Fan, Ph.D] explained.…

Fan’s team observed elongated rectangular scales arranged like overlapping shingles on the roof of a house. The butterflies they examined had slightly different scales, but both had ridges running the length of the scale with very small holes on either side that opened up onto an underlying layer.

The steep walls of the ridges help funnel light into the holes, Fan explained. The walls absorb longer wavelengths of light while allowing shorter wavelengths to reach a membrane below the scales. Using the images of the scales, the researchers created computer models to confirm this filtering effect. The nano-hole arrays change from wave guides for short wavelengths to barriers and absorbers for longer wavelengths, which act just like a high-pass filtering layer.

The group used actual butterfly-wing structures to collect sunlight, employing them as templates to synthesize solar-collecting materials. They chose the black wings of the Asian butterfly Papilio helenus Linnaeus, or Red Helen, and transformed them to titanium dioxide by a process known as dip-calcining. Titanium dioxide is used as a catalyst to split water molecules into hydrogen and oxygen. Fan’s group paired this butterfly-wing patterned titanium dioxide with platinum nanoparticles to increase its water-splitting power. The butterfly-wing compound catalyst produced hydrogen gas from water at more than twice the rate of the unstructured compound catalyst on its own.

This work was presented at the American Chemical Society’s 243rd annual meeting themed Chemistry of Life  in San Diego, California, March 25-29, 2012.

As I’ve noted previously, although that was specific to Morpho butterflies (my Feb. 14, 2012 posting), butterflies are being very generous with their intellectual property.

Unintended consequences: Australians not using sunscreens to avoid nanoparticles?

Friends of the Earth (FoE) Australia has waged a campaign against the use of nanosunscreens. It seems to have been somewhat successful but in a way that I imagine is upsetting. From the Feb. 9, 2012 news item on physorg.com,

The Cancer Council of Australia reports that we have one of the highest rates of skin cancer in the world, with over 440,000 people receiving medical treatment for skin cancers each year, and over 1,700 people dying of all types of skin cancer annually.

The survey of public attitudes towards sunscreens with nanoparticles, commissioned by the Australian Department of Industry, Innovation, Science, Research and Tertiary Education and conducted last month, showed that about 17% of people in Australia were so worried about the issue, they would rather risk skin cancer by going without sunscreen than use a product containing nanoparticles. [emphasis mine] [please see correction at the end of this posting]

The survey along with three research papers were presented at the 2012 International Conference on Nanoscience and Nanotechnology (ICONN) in Perth,Feb. 5-9.

One of the research studies indicates that claims of  ‘nano-free’ sunscreen products may be wrong, from the Feb. 9, 2012 news item on Nanowerk,

Scientists from Australia’s National Measurement Institute and overseas collaborators reported on a technique using the scattering of synchrotron light to determine the sizes of particles in sunscreens. They found that some commercial sunscreens that claim to be ‘nano-free’ do in fact contain nanostructured material. The findings highlight the need for clear definitions when describing nanomaterials.


The Australian Therapeutic Goods Administration has released a statement on safety of sunscreens containing nanoparticles that concluded: “… the current weight of evidence suggests that TiO2 (titanium dioxide) and ZnO (zinc oxide) nanoparticles do not reach viable skin cells, rather, they remain on the surface of the skin and in the outer layer of the skin…”

You can get more information about the studies in either linked news item. The Australian government’s sunscreen use survey is available on this page; the Australian Therapeutic Goods Administration review of the scientific literature on the safety of nanoscale (nanoparticulate) titanium dioxide and zinc oxide in sunscreens is available on this page; and the Cancer Council of Australia has information about sunscreens and nanoparticles on this page.

One can’t lay the blame for 17% of the population’s hesitance to use any sunscreens at one door but I hope that civil societies like FoEAustralia will give a little thought to the unintended consequences of their campaigns.

The campaign was against nanosunscreens not all sunscreens but presumably coupled with other influences, it seems to have upset a significant percentage of the population to the point that they refuse to use any sunscreens at all for fear of inadvertently being exposed to nanoparticles.

Feb. 10, 2012 update: It’s a very interesting response from FoEAustralia (from the Feb. 10, 2012 article by Simon Lauder for ABC  [Australian Broadcasting Corporation] News),

“We’ve decided to recall the safe sunscreen guides that we have produced this summer until we can revise them based on new information that comes in,” Elena McMaster, the nanotechnology campaigner with Friends of the Earth, said.

“What we see with this research is that in the absence of government regulation, the nanotech industry is able to more or less make up their own rules about what constitutes a nano material,” she said.

“We are obviously probably as shocked as people in the industry about the NMI research results.

“I can’t emphasise enough how urgent we think it is that the Government regulates.”

The best FoEAustralia can offer in the face of the rather shocking information that 17% of the adult population are avoiding sunscreens altogether is a plea for more government regulation of a product that doesn’t seem to be dangerous according to research.

Dexter Johnson in his Feb. 10, 2012 Nanoclast posting noted this about the study which found that sunscreens claiming ‘no nanomaterials/nanoparticles’ did contain some,

“What we see with this research is that in the absence of government regulation, the nanotech industry is able to more or less make up their own rules about what constitutes a nano material,” said Elena McMaster, a FoE spokesperson.

That’s one interpretation, I suppose. But it could also be that traditional sunscreens might contain nanoscale particles even though no attempt had been made to manufacture or add them to the mix. Unintentional nanoparticles, if you will, not unlike those created when the tires of your car drive over the pavement.

I wonder what kind of government regulations the FoE will request. Will each container of sunscreen have to be opened and its contents examined with a scattering of synchrotron light to determine particle size?

In fact, there’s some evidence that nanoparticles are all over the place, some of them created by nature, from the May 11, 2012 article New Evidence for Natural Synthesis of Silver Nanoparticles on Nanowiki,

“this creates the idea that there may be some sort of natural cycle returning some of the ions to nanoparticles.” [said Robert MacCuspie at NIST {US National Institute of Standards and Technology}] It also helps explain the discovery, over the past few years, of silver nanoparticles in locations like old mining regions that are not likely to have been exposed to man-made nanoparticles, but would have significant concentrations of silver ions. [emphasis mine]

My respect for FoEAustralia is seriously damaged by this stance they’ve taken. As far as I’m concerned they should admit they’ve made a mistake by using scare tactics to force some sort of confrontation over nanosunscreens and their strategy to force regulation of nanomaterials has backfired seriously.

Feb.21.12 correction: According to the information in the Feb. 20, 2012 posting on 2020 Science, the percentage of Australians likely to avoid using sunscreens is 13%,

This has just landed in my email in box from Craig Cormick at the Department of Industry, Innovation, Science, Research and Tertiary Education in Australia, and I thought I would pass it on given the string of posts on nanoparticles in sunscreens on 2020 Science over the past few years:

“An online poll of 1,000 people, conducted in January this year, shows that one in three Australians had heard or read stories about the risks of using sunscreens with nanoparticles in them,” Dr Cormick said.

“Thirteen percent of this group were concerned or confused enough that they would be less likely to use any sunscreen, whether or not it contained nanoparticles, putting them selves at increased risk of developing potentially deadly skin cancers.

“The study also found that while one in five respondents stated they would go out of their way to avoid using sunscreens with nanoparticles in them, over three in five would need to know more information before deciding.”

New research on nanoscale titanium dioxide shows toxic effects on marine life

Up till now, nanoscale titanium dioxide in water has not been viewed as toxic to marine life. A newly released study by researchers from  the University of California (UC) Center for Environmental Implications of Nanotechnology (UC CEIN) in the Jan. 20 in the journal PLoS ONE suggests otherwise. From the Jan. 24, 2012 news release on EurekAlert,

“Previous experiments have suggested that TiO2 does not affect aquatic organisms, but these experiments used artificial lighting that generated much lower levels of UVR than sunlight,” Miller [lead author and assistant research biologist Robert Miller] explains. “In these new experiments, we used lights simulating natural sunlight.”

But now, the authors say, “We show that relatively low levels of ultraviolet light, consistent with those found in nature, can induce toxicity of TiO2 nanoparticles to marine phytoplankton, the most important primary producers on Earth.

So, the relatively low levels of ultraviolet light in natural sunlight can induce toxicity in titanium dioxide nanoparticles. Here’s the reason for the concern,

“Application of nanomaterials in consumer products and manufacturing is quickly increasing, but there is concern that these materials, including nanoparticles, may harm the environment,” says Miller. “The oceans could be most at risk, since wastewater and factory discharges ultimately end up there.”

In all of the kerfuffle that the Friends of the Earth (FoE) and The ETC Group (and I assume others as well) have made over nanoscale ingredients in sunscreens they seem to have ignored the impact that these ingredients, when washed off our skin and into our water supply, may have on aquatic life.  I wonder if that will matter in the end. I mean if it turns out that nanoscale titanium dioxide is going to kill/damage “… the most important primary producers on Earth”, does it matter if FoE and the others succeed in mobilizing opposition to its use for what most experts might consider the wrong reasons.

Self-cleaning clothes

There’s a new cotton fabric that will self-clean when exposed to sunlight. From the Dec. 14, 2011 news item on Nanowerk,

Mingce Long and Deyong Wu say their fabric uses a coating made from a compound of titanium dioxide, the white material used in everything from white paint to foods to sunscreen lotions. Titanium dioxide breaks down dirt and kills microbes when exposed to some types of light. It already has found uses in self-cleaning windows, kitchen and bathroom tiles, odor-free socks and other products. Self-cleaning cotton fabrics have been made in the past, the authors note, but they self-clean thoroughly only when exposed to ultraviolet rays. So they set out to develop a new cotton fabric that cleans itself when exposed to ordinary sunlight.

Their report describes cotton fabric coated with nanoparticles made from a compound of titanium dioxide and nitrogen. They show that fabric coated with the material removes an orange dye stain when exposed to sunlight. Further dispersing nanoparticles composed of silver and iodine accelerates the discoloration process. The coating remains intact after washing and drying.

It’s nice to see that the coating doesn’t wash or dry off easily. Long’s and Wu’s report appears in the ACS [American Chemical Society] Applied Materials & Interfaces (“Realizing Visible-Light-Induced Self-Cleaning Property of Cotton through Coating N-TiO2 Film and Loading AgI Particles”).  Mingce Long is from the  School of Environmental Science and Engineering, Shanghai Jiao Tong University, China  and Deyong Wu is from the School of Chemical and Environmental Engineering, Hubei University for Nationalities, China.

Dexter Johnson of the Nanoclast blog on the IEEE website (Institute of Electrical and Electronics Engineers) notes this in his Dec. 22, 2011 posting,

… This is not just cotton treated with TiO2 but cotton treated with a mix of silver iodide (Agl) along with Nitrogen (N)-TiO2. This combination increased the photocatalytic activities of the material.

So, this is what I find so infuriating about coverage of nanotechnology. Couldn’t someone (besides me) have said that researchers had found a way of improving the photocatalytic performance of TiO2 in textiles so as to make their self-cleaning properties X times better than previous methods?

There you have it from an engineer who’s been the nanotech scene for quite some time. The concept of coating a textile with nanoscale titanium dioxide so it self-cleans is not new; the discovery in this case is a refinement which increased the photocatalytic properties of the textile in question.