Tag Archives: nanomaterials

Carbon nanotubes: faster, cheaper, easier, and more consistent

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One of the big problems with nanomaterials has to do with production issues such as: consistent size and shape. It seems that scientists at the US National Institute of Standards and Technology (NIST) have developed a technique for producing carbon nanotubes (CNTs) which addresses these issues. From a July 19, 2016 news item on Nanotechnology Now,

Just as many of us might be resigned to clogged salt shakers or rush-hour traffic, those working to exploit the special properties of carbon nanotubes have typically shrugged their shoulders when these tiniest of cylinders fill with water during processing. But for nanotube practitioners who have reached their Popeye threshold and “can’t stands no more,” the National Institute of Standards and Technology (NIST) has devised a cheap, quick and effective strategy that reliably enhances the quality and consistency of the materials–important for using them effectively in applications such as new computing technologies.

To prevent filling of the cores of single-wall carbon nanotubes with water or other detrimental substances, the NIST researchers advise intentionally prefilling them with a desired chemical of known properties. Taking this step before separating and dispersing the materials, usually done in water, yields a consistently uniform collection of nanotubes. In quantity and quality, the results are superior to water-filled nanotubes, especially for optical applications such as sensors and photodetectors.

A July 15, 2016 NIST news release, which originated the news item, expands on the theme,

The approach opens a straightforward route for engineering the properties of single-wall carbon nanotubes—rolled up sheets of carbon atoms arranged like chicken wire or honey combs—with improved or new properties.

“This approach is so easy, inexpensive and broadly useful that I can’t think of a reason not to use it,” said NIST chemical engineer Jeffrey Fagan.

In their proof-of-concept experiments, the NIST team inserted more than 20 different compounds into an assortment of single-wall carbon nanotubes with an interior diameter that ranged from more than 2 down to about 0.5 nanometers. Led by visiting researcher Jochen Campo, the scientists tested their strategy by using hydrocarbons called alkanes as fillers.

The alkanes, which include such familiar compounds as propane and butane, served to render the nanotube interiors unreactive. In other words, the alkane-filled nanotubes behaved almost as if they were empty—precisely the goal of Campo, Fagan and colleagues.

Compared with nanotubes filled with water and possibly ions, acids and other unwanted chemicals encountered during processing, empty nanotubes possess far superior properties. For example, when stimulated by light, empty carbon nanotubes fluoresce far brighter and with sharper signals.

Yet, “spontaneous ingestion” of water or other solvents by the nanotubes during processing is an “endemic but often neglected phenomenon with strong implications for the development of nanotube applications,” the NIST team wrote in a recent article in Nanoscale Horizons.

Perhaps because of the additional cost and effort required to filter out and gather nanotubes, researchers tend to tolerate mixed batches of unfilled (empty) and mostly filled single-wall carbon nanotubes. Separating unfilled nanotubes from these mixtures requires expensive ultracentrifuge equipment and, even then, the yield is only about 10 percent, Campo estimates.

“If your goal is to use nanotubes for electronic circuits, for example, or for fluorescent anti-cancer image contrast agents, then you require much greater quantities of materials of consistent composition and quality,” Campo explained, who was exploring these applications while doing postdoctoral research at the University of Antwerp. “This particular need inspired development of the new prefilling method by asking the question, can we put some passive chemical into the nanotube instead to keep the water out.”

From the very first simple experiments, the answer was yes. And the benefits can be significant. In fluorescence experiments, alkane-filled nanotubes emitted signals two to three times stronger than those emitted by water-filled nanotubes. Performance approached that of empty nanotubes—the gold standard for these comparisons.

As important, the NIST-developed prefilling strategy is controllable, versatile and easily incorporated into existing methods for processing single-wall carbon nanotubes, according to the researchers.

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

Enhancing single-wall carbon nanotube properties through controlled endohedral filling by J. Campo, Y. Piao, S. Lam, C. M. Stafford, J. K. Streit, J. R. Simpson, A. R. Hight Walker, and J. A. Fagan. Nanoscale Horiz., 2016,1, 317-324 DOI: 10.1039/C6NH00062B First published online 10 May 2016

This paper is open access but you do need to register on the site (it is a free registration).

Study nanomaterial toxicity without testing animals

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The process of moving on from testing on animals is laborious as new techniques are pioneered and, perhaps more arduously, people’s opinions and habits are changed. The People for the Ethical Treatment of Animals (PETA) organization focusing the research end of things has announced a means of predicting carbon nanotube toxicity in lungs according to an April 25, 2016 news item on Nanowerk (Note: A link has been removed),

A workshop organized last year [2015] by the PETA International Science Consortium Ltd has resulted in an article published today in the journal Particle and Fibre Toxicology (“Aerosol generation and characterization of multi-walled carbon nanotubes [MWCNTs] exposed to cells cultured at the air-liquid interface”). It describes aerosol generation and exposure tools that can be used to predict toxicity in human lungs following inhalation of nanomaterials.

An April 25, 2016 PETA press release on EurekAlert, which originated the news item, explains further without much more detail,

Nanomaterials are increasingly being used in consumer products such as paints, construction materials, and food packaging, making human exposure to these materials more likely. One of the common ways humans may be exposed to these substances is by inhalation, therefore, regulatory agencies often require the toxicity of these materials on the lungs to be tested. These tests usually involve confining rats to small tubes the size of their bodies and forcing them to breathe potentially toxic substances before they are killed. However, time, cost, scientific and ethical issues have led scientists to develop methods that do not use animals. The tools described in the new article are used to deposit nanomaterials (or other inhalable substances) onto human lung cells grown in a petri dish.

Co-authors of the Particle and Fibre Toxicology article are scientists from the PETA Science Consortium , The Dow Chemical Company, Baylor University, and the U.S. NTP Interagency Center for the Evaluation of Alternative Toxicological Methods (NICEATM).

“Promoting non-animal methods to assess nanotoxicity has been a focus of the PETA International Science Consortium”, said Dr. Monita Sharma, co-author of the publication and Nanotechnology Specialist at the Consortium, “we organized an international workshop last year on inhalation testing of nanomaterials and this review describes some of the tools that can be used to provide a better understanding of what happens in humans after inhaling these substances.” During the workshop, experts provided recommendations on the design of an in vitro test to assess the toxicity of nanomaterials (especially multi-walled carbon nanotubes) in the lung, including cell types, endpoints, exposure systems, and dosimetry considerations. Additional publications summarizing the outcomes of the workshop are forthcoming.

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

Aerosol generation and characterization of multi-walled carbon nanotubes exposed to cells cultured at the air-liquid interface by William W. Polk, Monita Sharma, Christie M. Sayes, Jon A. Hotchkiss, and Amy J. Clippinger. Particle and Fibre Toxicology201613:20 DOI: 10.1186/s12989-016-0131-y Published: 23 April 2016

This is an open access paper.

Use of nanomaterials in food for animals: the US Food and Drug Administration (FDA) issues a final guidance

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Bureaucratese is not my first language so the US Food and Drug Administration’s final guidance on the use of nanomaterials in animal food seems a little vague to me. That said, here’s the Aug. 5, 2015 news item on Nanowerk, which announced the guidance (Note: A link has been removed),

The U.S. Food and Drug Administration has issued a final guidance for industry, ‘Use of Nanomaterials in Food for Animals’ (pdf), which is intended to assist industry and other stakeholders in identifying potential issues related to safety or regulatory status of food for animals containing nanomaterials or otherwise involving the application of nanotechnology. This guidance is applicable to food ingredients intended for use in animal food which (1) consist entirely of nanomaterials, (2) contain nanomaterials as a component or (3) otherwise involve the application of nanotechnology.

An Aug. 4, 2015 FDA announcement, which originated the news item, provides more detail,

This final guidance addresses the legal framework for adding nanomaterial substances to food for animals and includes recommendations for submitting a Food Additive Petition (FAP) for a nanomaterial animal food ingredient. This guidance also recommends manufacturers consult with FDA early in the development of their nanomaterial animal food ingredient and before submitting an FAP. At this time, we are not aware of any animal food ingredient engineered on the nanometer scale for which there is generally available safety data sufficient to serve as the foundation for a determination that the use of such an animal food ingredient is generally recognized as safe (GRAS).

Nanotechnology is an emerging technology that allows scientists to create, explore, and manipulate materials on a scale measured in nanometers – particles so small that they cannot be seen with a regular microscope. These particles can have chemical, physical, and biological properties that differ from those of their larger counterparts, and nanotechnology has a broad range of potential applications.

Guidance documents represent the FDA’s current thinking on particular topics, policies, and regulatory issues. While “guidance for industry” documents are prepared primarily for industry, they also are used by FDA staff and other stakeholders to understand the agency’s interpretation of laws and policies.

Although this guidance has been finalized, you can submit comments at any time. To submit comments to the docket by mail, use the following address. Be sure to include docket number FDA-2013-D-1009 on each page of your written comments.

Division of Dockets Management
HFA-305
Food and Drug Administration
5630 Fishers Lane, Room 1061
Rockville, MD 20852

You can find the guidance here.

Carbon dioxide as a source for new nanomaterials

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Polish researchers have made a startling suggestion (from a Jan. 23, 2014 news item on Nanowerk),

In common perception, carbon dioxide is just a greenhouse gas, one of the major environmental problems of mankind. For Warsaw chemists CO2 became, however, something else: a key element of reactions allowing for creation of nanomaterials with unprecedented properties.

In reaction with carbon dioxide, appropriately designed chemicals allowed researchers from the Institute of Physical Chemistry of the Polish Academy of Sciences (IPC PAS) in Warsaw and the Faculty of Chemistry, Warsaw University of Technology, (WUT) for production of unprecedented nanomaterials.

Here’s an image the researchers use to illustrate their work,

Yellow tennis balls, spatially integrated in an adamant-like structure, symbolise crystal lattice of the microporous material resulting from self-assembly of nanoclusters. Orange balls imitate gas molecules that can adsorb in this material. The presentation is performed by Katarzyna Sołtys, a doctoral student from the Institute of Physical Chemistry of the Polish Academy of Sciences in Warsaw. (Source: IPC PAS, Grzegorz Krzyżewski).

Yellow tennis balls, spatially integrated in an adamant-like structure, symbolise crystal lattice of the microporous material resulting from self-assembly of nanoclusters. Orange balls imitate gas molecules that can adsorb in this material. The presentation is performed by Katarzyna Sołtys, a doctoral student from the Institute of Physical Chemistry of the Polish Academy of Sciences in Warsaw. (Source: IPC PAS, Grzegorz Krzyżewski).

The Jan. 23, 2014 IPC news release, which originated the news item, describes the work in more detail,

Carbon dioxide (CO2) is a natural component of Earth’s atmosphere. It is the most abundant carbon-based building block, and is involved in the synthesis of glucose, an energy carrier and building unit of paramount importance for living organisms.

“Carbon dioxide has been for years used in industrial synthesis of polymers. On the other hand, there has been very few research papers reporting fabrication of inorganic functional materials using CO2”, says Kamil Sokołowski, a doctoral student in IPC PAS.

Prof. Lewiński’s [Janusz Lewiński (IPC PAS, WUT)] group has shown that appropriately designed precursor compounds in reaction with carbon dioxide lead to fabrication of a microporous material (with pore diameters below 2 nm) resulting from self-assembly of luminescent nanoclusters. Novel microporous material, composed of building blocks with zinc carbonate core encapsulated in appropriately designed organic shell (hydroxyquinoline ligands), is highly luminescent, with photoluminescence quantum yield significantly higher than those of classical fluorescent compounds used in state-of-the-art OLEDs.

“Using carbon dioxide as a building block we were able to construct a highly porous and really highly luminescent material. Can it be used for construction of luminescent diodes or sensing devices? The discovery is new, the research work on the novel material is in progress, but we are deeply convinced that the answer is: yes”, says Sokołowski.

Already now it can be said that the novel material enjoys considerable interest. Polish and international patent applications were filed for the invention and the implementation work in cooperation with a joint venture company is in progress.

The design of precursors was inspired by nature, in particular by the binding of carbon dioxide in enzymatic systems of carbonic anhydrase, an enzyme responsible for fast metabolism of CO2 in human body. Effective enzyme activity is based on its active centre, where a hydroxyzinc (ZnOH) type reaction system is located.

“A hydroxyzinc reaction system occurs also in molecules of alkylzinc compounds, designed by us and used for fixation of carbon dioxide”, explains Sokołowski and continues: “These compounds are of particular interest for us, because in addition to hydroxyl group they contain also a reactive metal-carbon bond. It means that both the first and the second reaction system can participate in consecutive chemical transformations of such precursors”.

The research related to the chemistry of alkylhydroxyzinc compounds has an over 150 years of history and its roots are directly connected to the birth of organometallic chemistry. It was, however, only in 2011 and 2012 when Prof. Lewiński’s group has presented the first examples of stable alkylhydroxyzinc compounds obtained as a result of rationally designed synthesis.

The strategy for materials synthesis using carbon dioxide and appropriate alkylhydroxyzinc precursors, discovered by the researchers from Warsaw, seems to be a versatile tool for production of various functional materials. Depending on the composition of the reagents and the process conditions, a mesoporous material (with pore diameter from 2 to 50 nm) composed of zinc carbonate nanoparticles or multinuclear zinc nanocapsules for prospective applications in supramolecular chemistry can be obtained in addition to the material described above.

Further research of Prof. Lewiński’s group has shown that the mesoporous materials based on ZnCO3-nanoparticles can be transformed into zinc oxide (ZnO) aerogels. Mesoporous materials made of ZnO nanoparticles with extended surface can be used as catalytic fillings, allowing for and accelerating reactions of various gaseous reagents. Other potential applications are related to semiconducting properties of zinc oxide. That’s why the novel materials can be used in future in photovoltaic cells or as a major component of semiconductor sensing devices.

Good luck to the researchers as they find ways to turn a greenhouse gas into something useful.

US National Insitute for Occupational Health and Safety issues report on strategies for handling nanomaterials

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A Dec. 19, 2013 news item on Nanowerk announces the release of a recent publication about the safe handling of nanomaterials from the US National Institute of Occupational Health and Safety (NIOSH), Note: A link has been removed,

Occupational health risks associated with manufacturing and using nanomaterials are not yet clearly understood. However, initial toxicological data indicate that there is reason for caution. NIOSH is committed to promoting the responsible development and advancement of nanotechnology through its research and communication efforts to protect workers. NIOSH has taken a leading role in conducting research and making recommendations for nanotechnology safety in work settings. See the nanotechnology topic page for a list of documents and resources.

Recently, NIOSH has released a document titled, Current Strategies for Engineering Controls in Nanomaterial Production and Downstream Handling Processes, which provides information on how to control exposures for many of the most common processes seen in facilities that use or produce nanomaterials or nano-enabled products.

A Nov.8, 2013 NIOSH news release provides some additional insight into NIOSH’s strategy,,

Engineering controls are favored over administrative controls and personal protective equipment for lowering worker exposures, because they are designed to remove the hazard at the source, before it comes into contact with the worker. However, evidence showing the effectiveness of controls during the manufacture and downstream use of engineered nanomaterials in specific applications has been scarce.

The NIOSH recommendations fill a gap for science-based guidance that employers and workers can apply now, as research continues for better understanding of nanomaterial characteristics, and ways in which workers may be exposed, that may pose the risk of adverse health effects.

The consumer products market currently has more than 1,000 nanomaterial-containing products including makeup, sunscreen, food storage products, appliances, clothing, electronics, computers, sporting goods, and coatings. As more nanomaterials are introduced into the workplace and nano-enabled products enter the market, it is essential that producers and users of engineered nanomaterials ensure a safe and healthy work environment, the new document states.

Processes discussed in the document and for which controls are recommended and described include reactor operations and cleanout processes, small-scale weighing and handling of nanopowders, intermediate and finishing processes, and maintenance tasks. The document also includes recommendations for evaluating the performance of control technologies and control systems.

There’s a Dec. 9, 2013 NIOSH blog posting written by Jennifer L. Topmiller and Kevin H. Dunn which provides more detail about workers’ exposure to nanomaterials,,

Engineered nanomaterials are materials that are intentionally produced and have at least one primary dimension less than 100 nanometers (nm). Nanomaterials have properties different from those of larger particles of the same material, making them unique and desirable for specific product applications.  The consumer products market currently has more than 1,000 nanomaterial-containing products including makeup, sunscreen, food storage products, appliances, clothing, electronics, computers, sporting goods, and coatings [WWICS 2011].

It is difficult to estimate how many workers are involved in this field. By one estimate, there are 400,000 workers worldwide in the field of nanotechnology, with an estimated 150,000 of those in the United States [Roco et al. 2010]. The National Science Foundation has estimated that approximately 6 million workers will be employed in nanotechnology industries worldwide by 2020.

Occupational health risks associated with manufacturing and using nanomaterials are not yet clearly understood.  However, initial toxicological data indicate that there is reason for caution. NIOSH is committed to promoting the responsible development and advancement of nanotechnology through its research and communication efforts to protect workers. NIOSH has taken a leading role in conducting research and making recommendations for nanotechnology safety in work settings. …

…

The greatest exposures to raw nanomaterials are likely to occur in the workplace during production, handling, secondary processing, and packaging. In a review of exposure assessments conducted at nanotechnology plants and laboratories, Dr. Derk Brouwer determined that activities which resulted in exposures included harvesting (e.g., scraping materials out of reactors), bagging, packaging, and reactor cleaning [Brouwer 2010]. Downstream activities that may release nanomaterials include bag dumping, manual transfer between processes, mixing or compounding, powder sifting, and machining of parts that contain nanomaterials.  Similar to controlling hazards in traditional macro-scale manufacturing, engineering controls are recommended to reduce exposures to nanomaterials.

… Because little has been published on exposure controls in the production and use of nanomaterials, this document focuses on applications that have relevance to the field of nanotechnology and on engineering control technologies currently used, and known to be effective, in other industries.

Assessing how well the exposure control works is also essential for verifying that the exposure goals of the facility have been successfully met. This document covers a range of control evaluation tools including airflow visualization and measurement and containment test methods, such as tracer gas testing. Additional methods, such as video exposure monitoring, also provide information on critical task-based exposures and helps identify high-exposure activities and help provide the basis for interventions.

intriguingly, there’s also a plea for partnership at the end of this Dec. 9, 2013 NIOSH posting,

Producers and users of engineered nanomaterials are invited and encouraged to partner with NIOSH. Companies that have installed exposure controls, such as local exhaust ventilation, or are interested in assessing and reducing worker exposures can work with NIOSH engineers to develop and evaluate exposure mitigation options. Partnering with NIOSH not only benefits your company by providing an assessment of process emissions and recommending effective exposure control approaches  but also expands the knowledge base that benefits the industry as a whole.  Please feel free to contact us through the comment section below or by sending an e-mail to nioshblog@cdc.gov.  Thank for your interest in protecting workers!

You can find the NIOSH report, Current Strategies for Engineering Controls in Nanomaterial Production and Downstream Handling Processes here.

NanoDefine: a project for implementing the European Union’s definition for nanomaterials

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Here”s an excerpt from the Dec. 13, 2013 news item on Azonano about a new consortium focused on measuring nanomaterials and, if I understand the news item rightly, refining the definition so that it can be implemented,

A 29-partner consortium of top European RTD [?] performers, metrology institutes, and nanomaterials and instrument manufacturers, gathered at a launch meeting in Wageningen, NL, [Netherlands] last month to begin the mobilisation of the critical mass of expertise required to establish the measurement tools and scientific data that help to implement the EU recommendation on the definition of a nanomaterial.

We have come a long way in exploring the full potential of nano as a key enabling technology, yet, there are still uncertainties surrounding environment, health and safety (EHS) issues and the questions that need to be addressed: what is or isn’t a nanomaterial. One challenge consists in the development of methods that reliably identify, characterize and measure nanomaterials (NM) both as substance and in various products and matrices. In responses, the European Commission has recently recommended a definition of NM as a reference to determine this (2011/696/EU).

The NanoDefine project will explicitly address this question over the next four years.

I have written about the European Union’s definition of nanomaterials in an Oct, 18, 2011 posting,

After all the ‘sturm und drang’ in the last few months (my Sept. 8, 2011 posting summarizing some of the lively discussion), a nanomaterials definition for Europe has been adopted. It is the first ‘cross-cutting’ nanomaterials definition to date according to the Oct. 18, 2011 news item on Nanowerk,

“Nanomaterials” are materials whose main constituents have a dimension of between 1 and 100 billionth of a metre, according to a Recommendation on the definition of nanomaterial (pdf) adopted by the European Commission today. The announcement marks an important step towards greater protection for citizens, clearly defining which materials need special treatment in specific legislation.

I also featured some specific critiques of the then newly proclaimed definition in an Oct. 19, 2011 posting and again in an Oct. 20, 2011 posting.

The Institute of Nanotechnology Dec. 12, 2013 news release, which originated the news item, provides more details about the NanoDefine project,

Based on a comprehensive evaluation of existing methodologies and a rigorous intra-lab and inter-lab comparison, validated measurement methods and instruments will be developed that are robust, readily implementable, cost-effective and capable to reliably measure the size of particles in the range of 1 – 100 nm, with different shapes, coatings and for the widest possible range of materials, in various complex media and products. Practical case studies will assess their applicability for various sectors, including food/feed, cosmetics etc.

One major outcome of the project will be the establishment of an integrated tiered approach including validated rapid screening methods (tier 1) and validated in depth methods (tier 2), with a user manual to guide end-users, such as manufacturers, regulatory bodies and contract laboratories, to implement the developed methodology.

NanoDefine will closely collaborate with its sister projects in the NanoSafety Cluster (www.nanosafetycluster.eu) as well as engage with international EHS, RTD and metrology initiatives. NanoDefine will also be strongly linked to main standardization bodies, such as CEN, ISO and OECD, by actively participating in Technical Commissions and Working Groups, and by proposing specific ISO/CEN work items, to integrate the developed and validated methodology into the current standardization work.

For more information:
NanoDefine: ‘Development of an integrated approach based on validated and standardized methods to support the implementation of the EC recommendation for a definition of nanomaterial’ receives funding from the European Community’s Seventh Framework Programme under grant agreement n°604347 and runs from 1/11/2013 – 31/10/2017

Visit the project website: www.nanodefine.eu (currently under construction) [as of Dec. 13, 2013 there is no landing page]
Contact the Project Coordinators:
hans.marvin@wur.nl
wim.beek@wur.nl
stefan.weigel@wur.nl
rudolf.reuther@enas-online.com

Visit the NanoSafety Cluster website: www.nanosafetycluster.eu

I have searched on this blog to see if I’ve stumbled across the Institute of Nanotechnology, located in the UK, previously but cannot find any other mentions (which may be due to the search function and my impatience for paging through apparently irrelevant search results). At any rate, here’s more about the institute from its About Us webpage (Note: Links have been removed),

Background

The Institute of Nanotechnology (IoN) was founded by Ottilia Saxl in January 1997. It is a registered Charity, whose core activities are focused on education and training in nanotechnology. It grew out of the Centre for Nanotechnology, part funded by the DTI through the UK’s National Initiative on Nanotechnology (NION). The Institute was one of the world’s first nanotechnology information providers and is now a global leader.

The Institute works closely with governments, universities, researchers, companies and the general public to educate and inform on all aspects of nanotechnology. It also organises various international scientific events, conferences and educational courses that examine the implications of nanotechnology across a wide variety of themes and sectors.

As most people know (except maybe policymakers), implementation is the tricky part of any rule, policy, and/or law and  the definitions are crucial.

Danish evaluate research on absorption of nanomaterials through the skin

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An Oct. 3, 2013 news item on Azonano announces a report produced by the Danish Environmental Protection Agency on the state of research into dermal absorption of nanomaterials  (Note: A link has been removed),

 A new report published by the Danish Environmental Protection Agency (EPA) provides a comprehensive evaluation of the knowledge base regarding the dermal absorption of nanomaterials.

The report is the final output of the project “Dermal absorption of Nanomaterials”, which forms part of the “Better Control of Nano” initiative 2012 – 2015 conducted by the Danish EPA with the aim of further clarifying possible risks to consumers and the environment from nanomaterials.

The overall objectives of the project – which was led by the Institute of Occupational Medicine (IOM) working with COWI A/S – were to:  i) gather and evaluate the existing knowledge concerning the dermal absorption of nanomaterials, ii) assess the need to generate new knowledge, and iii) develop recommendations for the most suitable skin models, measurement methods and relevant candidate nanomaterials for future experimental testing.

The report: Dermal Absorption of Nanomaterials Part of the ”Better control of nano” initiative 2012 – 2015 Environmental Project No. 1504, 2013 gives a good description of skin and a good technical overview of the literature and the state of the research which, for the interested reader, could supply the basis for a better understanding of how to read research papers on this topic.  The report does not offer consumer information about nano sunscreens, etc.

Here’ are some of the conclusions from the Executive Summary,

One of the key challenges in assessing the literature on the physicochemical properties influencing dermal penetration/absorption of nanomaterials is that it is difficult to draw conclusions due to either: i) limitations in the reporting of physicochemical data, and/or, ii) the alteration of multiple experimental parameters in a non-systematic way. The issue of a lack of information on nanoparticle physicochemical properties is common, yet the most challenging aspect is the alteration of multiple experimental parameters whereby multiple characteristics such as shape, charge, coating, size can all be changed. This means that little meaningful comparison of results can be made within a single experimental study, let alone between studies.

Despite such challenges, some key conclusions can be drawn. [emphasis mine] Whilst there are many conflicting results, on balance the literature seems to suggest that absorption of particles in the nano-range through the skin is possible although occurs to a very low degree and that the level of penetration, depending on chemistry and experimental conditions, may be greater than for larger particles. The role of size is considered a critical component of dermal absorption but this in itself does not seem to guarantee absorption or lack of as other properties can also influence dermal absorption markedly. In addition, particle size is not necessarily a constant parameter as agglomeration of particles can occur over time and also in relation to experimental conditions (e.g. presence of surfactants within particle vehicle formulation). However, whilst this issue of agglomeration has been suggested as being important (as well as an important experimental variable), agglomeration state is often not reported within studies.

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

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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.

US National Institute of Occupational Health and Safety sets recommendations for workplace exposure to carbon nanofibers/nanotubes

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Earlier this week, the US National Institute of Occupational Health and Safety (NIOSH) set recommendations for workplace exposure to carbon nanotubes and carbon nanofibers. According to the Apr. 24, 2013 media advisory from the US Centers for Disease Control and Prevention (NIOSH’s parent agency), the recommendations have been issued in the new Current Intelligence Bulletin (CIB) no. 65. From CIB No. 65,

NIOSH is the leading federal agency conducting research and providing guidance on the occupational safety and health implications and applications of nanotechnology. As nanotechnology continues to expand into every industrial sector, workers will be at an increased risk of exposure to new nanomaterials. Today, nanomaterials are found in hundreds of products, ranging from cosmetics, to clothing, to industrial and biomedical applications. These nanoscale-based products are typically called “first generation” products of nanotechnology. Many of these nanoscale-based products are composed of engineered nanoparticles, such as metal oxides, nanotubes, nanowires, quantum dots, and carbon fullerenes (buckyballs), among others. Early scientific studies have indicated that some of these nanoscale particles may pose a greater health risk than the larger bulk form of these materials.

Results from recent animal studies indicate that carbon nanotubes (CNT) and carbon nanofibers (CNF) may pose a respiratory hazard. CNTs and CNFs are tiny, cylindrical, large aspect ratio, manufactured forms of carbon. There is no single type of carbon nanotube or nanofiber; one type can differ from another in shape, size, chemical composition (from residual metal catalysts or functionalization of the CNT and CNF) and other physical and chemical characteristics. Such variations in composition and size have added to the complexity of understanding their hazard potential. Occupational exposure to CNTs and CNFs can occur not only in the process of manufacturing them, but also at the point of incorporating these materials into other products and applications. A number of research studies with rodents have shown adverse lung effects at relatively low-mass doses of CNT and CNF, including pulmonary inflammation and rapidly developing, persistent fibrosis. Although it is not known whether similar adverse health effects occur in humans after exposure to CNT and CNF, the results from animal research studies indicate the need to minimize worker exposure.

This NIOSH CIB, (1) reviews the animal and other toxicological data relevant to assessing the potential non-malignant adverse respiratory effects of CNT and CNF, (2) provides a quantitative risk assessment based on animal dose-response data, (3) proposes a recommended exposure limit (REL) of 1 μg/m3 elemental carbon as a respirable mass 8-hour time-weighted average (TWA) concentration, [emphasis mine] and (4) describes strategies for controlling workplace exposures and implementing a medical surveillance program. The NIOSH REL is expected to reduce the risk for pulmonary inflammation and fibrosis. However, because of some residual risk at the REL and uncertainty concerning chronic health effects, including whether some types of CNTs may be carcinogenic, continued efforts should be made to reduce exposures as much as possible.

The recommended exposure, for those of us who can’t read the technical notation, translates to one microgram per cubic meter per eight-hour workday.  In other words, almost zero. Note that this is a recommendation and not a regulation. H/T Apr. 26, 2013 article by Elizabeth Wiese for USA Today

My Mar. 12, 2013 posting highlights some of the NIOSH research which preceded this recommendation.

Free the nano—stop patenting publicly funded research

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Joshua Pearce, a professor at Michigan Technological University, has written a commentary on patents and nanotechnology for Nature magazine which claims the current patent regimes strangle rather than encourage innovation. From the free article,  Physics: Make nanotechnology research open-source by Joshua Pearce in Nature 491, 519–521 (22 November 2012) doi:10.1038/491519a (Note: I have removed footnotes),

Any innovator wishing to work on or sell products based on single-walled carbon nanotubes in the United States must wade through more than 1,600 US patents that mention them. He or she must obtain a fistful of licences just to use this tubular form of naturally occurring graphite rolled from a one-atom-thick sheet. This is because many patents lay broad claims: one nanotube example covers “a composition of matter comprising at least about 99% by weight of single-wall carbon molecules”. Tens of others make overlapping claims.

…

Patent thickets occur in other high-tech fields, but the consequences for nanotechnology are dire because of the potential power and immaturity of the field. Advances are being stifled at birth because downstream innovation almost always infringes some early broad patents. By contrast, computing, lasers and software grew up without overzealous patenting at the outset.

…

Nanotechnology is big business. According to a 2011 report by technology consultants Cientifica, governments around the world have invested more than US$65 billion in nanotechnology in the past 11 years [my July 15, 2011 posting features an interview with Tim Harper, Cientfica CEO and founder, about the then newly released report]. The sector contributed more than $250 billion to the global economy in 2009 and is expected to reach $2.4 trillion a year by 2015, according to business analysts Lux Research. Since 2001, the United States has invested $18 billion in the National Nanotechnology Initiative; the 2013 US federal budget will add $1.8 billion more.

This investment is spurring intense patent filing by industry and academia. The number of nanotechnology patent applications to the US Patent and Trademark Office (USPTO) is rising each year and is projected to exceed 4,000 in 2012. Anyone who discovers a new and useful process, machine, manufacture or composition of matter, or any new and useful improvement thereof, may obtain a patent that prevents others from using that development unless they have the patent owner’s permission.

Pearce makes some convincing points (Note: I have removed a footnote),

Examples of patents that cover basic components include one owned by the multinational chip manufacturer Intel, which covers a method for making almost any nanostructure with a diameter less than 50 nm; another, held by nanotechnology company NanoSys of Palo Alto, California, covers composites consisting of a matrix and any form of nanostructure. And Rice University in Houston, Texas, has a patent covering “composition of matter comprising at least about 99% by weight of fullerene nanotubes”.

The vast majority of publicly announced IP licence agreements are now exclusive, meaning that only a single person or entity may use the technology or any other technology dependent on it. This cripples competition and technological development, because all other would-be innovators are shut out of the market. Exclusive licence agreements for building-block patents can restrict entire swathes of future innovation.

Pearce’s argument for open source,

This IP rush assumes that a financial incentive is necessary to innovate, and that without the market exclusivity (monopoly) offered by a patent, development of commercially viable products will be hampered. But there is another way, as decades of innovation for free and open-source software show. Large Internet-based companies such as Google and Facebook use this type of software. Others, such as Red Hat, make more than $1 billion a year from selling services for products that they give away for free, like Red Hat’s version of the computer operating system Linux.

An open-source model would leave nanotechnology companies free to use the best tools, materials and devices available. Costs would be cut because most licence fees would no longer be necessary. Without the shelter of an IP monopoly, innovation would be a necessity for a company to survive. Openness reduces the barrier for small, nimble entities entering the market.

John Timmer in his Nov. 23, 2012 article for Wired.co.uk expresses both support and criticism,

Some of Pearce’s solutions are perfectly reasonable. He argues that the National Science Foundation adopt the NIH model of making all research it funds open access after a one-year time limit. But he also calls for an end of patents derived from any publicly funded research: “Congress should alter the Bayh-Dole Act to exclude private IP lockdown of publicly funded innovations.” There are certainly some indications that Bayh-Dole hasn’t fostered as much innovation as it might (Pearce notes that his own institution brings in 100 times more money as grants than it does from licensing patents derived from past grants), but what he’s calling for is not so much a reform of Bayh-Dole as its elimination.

Pearce wants changes in patenting to extend well beyond the academic world, too. He argues that the USPTO should put a moratorium on patents for “nanotechnology-related fundamental science, materials, and concepts.” As we described above, the difference between a process innovation and the fundamental properties resulting in nanomaterial is a very difficult thing to define. The USPTO has struggled to manage far simpler distinctions; it’s unrealistic to expect it to manage a moratorium effectively.

While Pearce points to the 3-D printing sector admiringly, there are some issues even there, as per Mike Masnick’s Nov.  21, 2012 posting on Techdirt.com (Note:  I have removed links),

We’ve been pointing out for a while that one of the reasons why advancements in 3D printing have been relatively slow is because of patents holding back the market. However, a bunch of key patents have started expiring, leading to new opportunities. One, in particular, that has received a fair bit of attention was the Formlabs 3D printer, which raised nearly $3 million on Kickstarter earlier this year. It got a ton of well-deserved attention for being one of the first “low end” (sub ~$3,000) 3D printers with very impressive quality levels.

Part of the reason the company said it could offer such a high quality printer at a such a low price, relative to competitors, was because some of the key patents had expired, allowing it to build key components without having to pay astronomical licensing fees. A company called 3D Systems, however, claims that Formlabs missed one patent. It holds US Patent 5,597,520 on a “Simultaneous multiple layer curing in stereolithography.” While I find it ridiculous that 3D Systems is going legal, rather than competing in the marketplace, it’s entirely possible that the patent is valid. It just highlights how the system holds back competition that drives important innovation, though.

3D Systems claims that Formlabs “took deliberate acts to avoid learning” about 3D Systems’ live patents. The lawsuit claims that Formlabs looked only for expired patents — which seems like a very odd claim. Why would they only seek expired patents? …

I strongly suggest reading both Pearce’s and Timmer’s articles as they both provide some very interesting perspectives about nanotechnology IP (intellectual property) open access issues. I also recommend Mike Masnick’s piece for exposure to a rather odd but unfortunately not uncommon legal suit designed to limit competition in a relatively new technology (3-D printers).