Posts Tagged ‘silver nanoparticles’

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Nanosilver resistance

Wednesday, May 8th, 2013

Researchers at Australia’s University of New South Wales (UNSW) have published a study where they claim that bacteria have develop resistance to nanosilver, a product used widely for its antibacterial properties. From the May 8, 2013 news item on ScienceDaily,

Researchers from UNSW have cautioned that more work is needed to understand how micro-organisms respond to the disinfecting properties of silver nano-particles, increasingly used in consumer goods, and for medical and environmental applications.

Although nanosilver has effective antimicrobial properties against certain pathogens, overexposure to silver nano-particles can cause other potentially harmful organisms to rapidly adapt and flourish, a UNSW study reveals.

The May 8, 2013 UNSW news release, which originated the news item, notes,

“We found an important natural ability of a widely occurring bacteria to adapt quite rapidly to the antimicrobial action of nanosilver. This is the first unambiguous evidence of this induced adaptation,” says co-author Dr Cindy Gunawan, from the UNSW School of Chemical Engineering.

Using an experimental culture, UNSW researchers observed that nanosilver was effective in suppressing a targeted bacteria (Escherichia coli), but that its presence initiated the unexpected emergence, adaptation and abnormally fast growth of another bacteria species (Bacillus).

The news release mentions some of the implications,

The efficacy of nanosilver to suppress certain disease-causing pathogens has been well-documented, and as a result, it has become widely used in medicine to coat bandages and wound dressings. It also has environmental uses in water and air purification systems, and is used in cosmetics and detergents, and as a surface coating for things like toys and tupperware.

But the researchers say this exploitation of nanosilver’s antimicrobial properties have “gained momentum due in part to a lack of evidence for the potential development of resistant microorganisms”.

“Antimicrobial action of nanosilver is not universal and the widespread use of these products should take into consideration the potential for longer-term adverse outcomes,” says Gunawan.

The researchers say these adverse impacts could be more pronounced given the near-ubiquitous nature of the Bacillus bacteria, which originate from airborne spores, and because the resistance trait can potentially be transferred to the genes of other micro-organisms.

“For the medical use of nanosilver, this implies the potential for reduced efficacy and the development of resistant populations in clinical settings,” says co-author Dr Christopher Marquis, a senior lecturer from the UNSW School of Biotechnology and Biomolecular Sciences. [emphasis mine]

I have touched on the issue of resistance and bacteria previously in the context of finding new ways to deal with them in my Don’t kill bacteria, uninvite them posting of Aug. 13, 2012 about developing new materials that resist bacteria and and there’s my mention of Sharklet, a material based on the nanoscale properties of sharkskin and which has potential for use in hospital settings, in my Feb. 10, 2011 posting.

For those who’d like to read about this work from the University of New South Wales, the ScienceDaily news item provides a link to and a citation for the paper which has been published in Small. This paper is behind a paywall and the publisher (Wiley Online Library), puzzingly and in comparison to other publishers, has made the paper hard to find.

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Posted in medicine, nanotechnology, risk | No Comments »

More than human—a bionic ear that extends hearing beyond the usual frequencies

Thursday, May 2nd, 2013

It’s now possible to print a bionic ear in 3D that can hear beyond the human range and all you need is off-the-shelf printing equipment—and technical expertise. A May 2, 2013 news item on Azonano provides more detail,

Scientists at Princeton University used off-the-shelf printing tools to create a functional ear that can “hear” radio frequencies far beyond the range of normal human capability.

“In general, there are mechanical and thermal challenges with interfacing electronic materials with biological materials,” said Michael McAlpine, an assistant professor of mechanical and aerospace engineering at Princeton and the lead researcher. “Previously, researchers have suggested some strategies to tailor the electronics so that this merger is less awkward. That typically happens between a 2D sheet of electronics and a surface of the tissue. However, our work suggests a new approach — to build and grow the biology up with the electronics synergistically and in a 3D interwoven format.”

McAlpine’s team has made several advances in recent years involving the use of small-scale medical sensors and antenna. Last year, a research effort led by McAlpine and Naveen Verma, an assistant professor of electrical engineering, and Fio Omenetto of Tufts University, resulted in the development of a “tattoo” made up of a biological sensor and antenna that can be affixed to the surface of a tooth.

The tooth tattoo is mentioned in my Nov. 9, 2012 posting; I focused more on Tufts University than Princeton in that piece. As for the ear (from the news item on Azonano),

The finished ear consists of a coiled antenna inside a cartilage structure. Two wires lead from the base of the ear and wind around a helical “cochlea” – the part of the ear that senses sound – which can connect to electrodes. Although McAlpine cautions that further work and extensive testing would need to be done before the technology could be used on a patient, he said the ear in principle could be used to restore or enhance human hearing. He said electrical signals produced by the ear could be connected to a patient’s nerve endings, similar to a hearing aid. The current system receives radio waves, but he said the research team plans to incorporate other materials, such as pressure-sensitive electronic sensors, to enable the ear to register acoustic sounds.

Here’s the technique the researchers used to create their bionic ear (from the news item),

Standard tissue engineering involves seeding types of cells, such as those that form ear cartilage, onto a scaffold of a polymer material called a hydrogel. However, the researchers said that this technique has problems replicating complicated three dimensional biological structures. Ear reconstruction “remains one of the most difficult problems in the field of plastic and reconstructive surgery,” they wrote.

To solve the problem, the team turned to a manufacturing approach called 3D printing. These printers use computer-assisted design to conceive of objects as arrays of thin slices. The printer then deposits layers of a variety of materials – ranging from plastic to cells – to build up a finished product. Proponents say additive manufacturing promises to revolutionize home industries by allowing small teams or individuals to create work that could previously only be done by factories.

Creating organs using 3D printers is a recent advance; several groups have reported using the technology for this purpose in the past few months. But this is the first time that researchers have demonstrated that 3D printing is a convenient strategy to interweave tissue with electronics.

The technique allowed the researchers to combine the antenna electronics with tissue within the highly complex topology of a human ear. The researchers used an ordinary 3D printer to combine a matrix of hydrogel and calf cells with silver nanoparticles that form an antenna. The calf cells later develop into cartilage.

Here’s an image of the ear,

Scientists used 3-D printing to merge tissue and an antenna capable of receiving radio signals. Credit: Photo by Frank Wojciechowski

Scientists used 3-D printing to merge tissue and an antenna capable of receiving radio signals. Credit: Photo by Frank Wojciechowski

For interested parties,a link to and a citation for the published research,

A 3D Printed Bionic Ear by Manu S Mannoor , Ziwen Jiang , Teena James , Yong Lin Kong , Karen A Malatesta , Winston Soboyejo , Naveen Verma , David H Gracias , and Michael C. McAlpine. Nano Lett., Just Accepted Manuscript DOI: 10.1021/nl4007744 Publication Date (Web): May 1, 2013

Copyright © 2013 American Chemical Society

This article is behind a paywall.

At this point, the ear is strictly for use in the laboratory they have not run any ‘in vivo’ experiments, which would be one of the next steps and a prerequisite before  human clinical trials are considered.

I have written about human enhancement before, notably in my Aug. 30, 2011 posting where I highlighted this excerpt from an article by Paul Hochman,

“I don’t think I would have said this if it had never happened,” says Bailey, referring to the accident that tore off his pinkie, ring, and middle fingers. “But I told Touch Bionics I’d cut the rest of my hand off if I could make all five of my fingers robotic.” [originally excerpted from Paul Hochman's Feb. 1, 2010 article, Bionic Legs, i-Limbs, and Other Super Human Prostheses You'll Envy for Fast Company]

The Bailey quote stimulated this question for me, what would you choose if you could get an ear that hears beyond the human range?

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Posted in electronics, human enhancement, nanotechnology | No Comments »

Brewing up silver nanoparticles

Wednesday, April 24th, 2013

The last time I featured green tea was in the context of couture in this June 8, 2012 posting,

First, a June 7, 2012 article by Jane Wakefield about fashion and technology on the BBC News website that features a designer, Suzanne Lee, who grows clothing. I’m glad to see Lee is still active (I first mentioned her work with bacteria and green tea in a July 13, 2010 posting). From Wakefield’s 2012 article,

“I had a conversation with a biologist who raised the idea of growing a garment in a laboratory,” she [Biocouture designer, Suzanne Lee] told the BBC.

In her workshop in London, she is doing just that.

Using a recipe of green tea, sugar, bacteria and yeast she is able to ‘grow’ a material which she describes as a kind of “vegetable leather”.

It turns out there are other uses for green tea, aside from its function in couture or as a beverage with health benefits, according to an Apr. 24, 2013 news item on Nanowerk (Note: A link has been removed),

Already renowned for its beneficial effects on human health, green tea could have a new role — along with other natural plant-based substances — in a healthier, more sustainable production of the most widely used family of nanoparticles, scientists say. Published in ACS [American Chemical Society] Sustainable Chemistry & Engineering, their Perspective article (“Greener Techniques for the Synthesis of Silver Nanoparticles using Plant Extracts, Enzymes, Bacteria, Biodegradable Polymers and Microwaves”) concludes that greener methods for making silver nanoparticles are becoming available.

The Apr. 24, 2013 ACS PressPak news release, which originated the news item,  offers a brief description of the researchers’ article,

The article describes how extracts from plants — such as green tea plants, sunflowers, coffee, fruit and peppers — have emerged as possible substitutes that can replace toxic substances normally used to make the nanoparticles. In addition, extracts from bacteria and fungi, as well as natural polymers, like starches, could serve as substitutes. “These newer techniques for greener AgNP synthesis using biorenewable materials appear promising as they do not have any toxic materials deployed during the production process,” the scientists say.

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

Greener Techniques for the Synthesis of Silver Nanoparticles using Plant Extracts, Enzymes, Bacteria, Biodegradable Polymers and Microwaves by Deepika Hebbalalu, Jacob Lalley, Mallikarjuna N Nadagouda, and Rajender Singh Varma. ACS Sustainable Chem. Eng., Just Accepted Manuscript DOI: 10.1021/sc4000362 Publication Date (Web): March 28, 2013
Copyright © 2013 American Chemical Society

This paper is behind a paywall.

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Posted in environment, nanotechnology | No Comments »

Clay disks and flowerpots that purify water

Monday, March 4th, 2013

Ben Schiller writes in a Mar. 1, 2013 article for Fast Company about a not-for-profit organization, PureMadi, a joint venture between the University of Virginia (US) and the University of Venda (South Africa) and its water purification technology,

PuriMadi has already built a factory in the Limpopo province of South Africa and hopes to expand further. “Eventually that factory will be capable of producing about 500 to 1,000 filters per month, and our 10-year plan is to build 10 to 12 factories in South Africa and other countries,” Smith says. “We plan to eventually serve at least 500,000 people per year with new filters.”

The University of Virginia Feb. 5, 2013 news release by Fariss Samarrai describes both a disc and a flowerpot version of the water purification technology (Note: Some links have been removed),

PureMadi, a nonprofit University of Virginia organization, will introduce a new invention – a simple ceramic water purification tablet – during its one-year celebration event Friday [Feb. 8, 2013] from 7 to 11 p.m. at Alumni Hall.

Called MadiDrop, the tablet – developed and extensively tested at U.Va. – is a small ceramic disk impregnated with silver or copper nanoparticles. It can repeatedly disinfect water for up to six months simply by resting in a vessel where water is poured. It is being developed for use in communities in South Africa that have little or no access to clean water.

“Madi” is the Tshivenda South African word for water. PureMadi brings together U.Va. professors and students to improve water quality, human health, local enterprise and quality of life in the developing world. The organization includes students and faculty members from engineering, architecture, medicine, nursing, business, commerce, economics, anthropology and foreign affairs.

During the past year, PureMadi has established a water filter factory in Limpopo province, South Africa, employing local workers. The factory produced several hundred flowerpot-like water filters, according to James Smith, a U.Va. civil and environmental engineer who co-leads the project with Dr. Rebecca Dillingham, director of U.Va.’s Center for Global Health.

Here’s the flowerpot filter,

A worker molds a filter from local clay, sawdust and water. (Photo: Rachel Schmidt)


A worker molds a filter from local clay, sawdust and water. (Photo: Rachel Schmidt)

Here are the discs or, as they are known, the MadiDrops,

The new MadiDrops can be produced in the same factories as the filters. (Photo: Rachel Schmidt)


The new MadiDrops can be produced in the same factories as the filters. (Photo: Rachel Schmidt)

The factory is more than just a producer of water purification technologies, from the University of Virgina news release,

“Eventually that factory will be capable of producing about 500 to 1,000 filters per month, and our 10-year plan is to build 10 to 12 factories in South Africa and other countries,” Smith said. “Each filter can serve a family of five or six for two to five years, so we plan to eventually serve at least 500,000 people per year with new filters.”

The idea is to create sustainable businesses that serve their communities and employ local workers. A small percentage of the profits go back to PureMadi and will be used to help establish more factories.

The PureMadi website’s About page offers more information about the partners, the technology, and the economic impact,

PureMadi has been created by an interdisciplinary collaboration of students and faculty at the University of Virginia.  In partnership with the University of Venda in Thohoyandou, South Africa, and developing-world communities in Limpopo Province, South Africa, PureMadi is working to provide sustainable solutions to global water problems.

Our first project is the development of a sustainable, ceramic water filter factory in South Africa.  Ceramic filters are a point-of-use (e.g. household-level) water treatment technology.  Ceramic filters can be produced with local materials (clay, sawdust, and water) and local labor. The materials are mixed in appropriate proportions, pressed into the shape of a filter pot, and fired in a kiln at 900 ˚C.  Upon firing, the clay forms a ceramic and the sawdust combusts, leaving a porous ceramic matrix for filtration.  In addition, the filters are treated with a dilute solution of silver nanoparticles.  The nanoparticles lodge in the pore space of the ceramic matrix and act as a highly effective disinfectant for waterborne pathogens like Vibrio cholerae and pathogenic strains of Escherichia coli.   Untreated water can then be passed through the filter and collected in a lower reservoir with a spigot to obtain purified water.

In the field and in the laboratory, we have demonstrated that this technology is highly effective at purifying water and the filters are socially acceptable to developing-world communities.  In some of our most recent work, we have shown that the filters significantly improve the health outcomes of human populations using the filters relative to groups who only drink untreated water.

A filter factory can become a sustainable business venture that provides economic stimulus to the local community.  Our goal is to create a blueprint for a successful factory, including its architecture, efficiency of water and energy use, technological performance of the filter itself, and an effective and sustainable business model.

While the flowerpot filter has been well received the MadiDrop fills another need, from the University of Virginia news release,

MadiDrop is an alternative to the flowerpot filter, but ideally would be used in conjunction with it. The plan is to mass-produce the product at the same factories where the PureMadi filters are produced.

“MadiDrop is cheaper, easier to use, and is easier to transport than the PureMadi filter, but because it is placed into the water, rather than having the water filter through it, the MadiDrop is not effective for removing sediment in water that causes discoloration or flavor impairment,” Smith said. “But its ease of use, cost-effectiveness and simple manufacturing process should allow us to make it readily available to a substantial population of users, more so than the more expensive PureMadi filter.”

Testing shows that the filters are safe to use and release only trace amounts of silver or copper particles, well within the safe water standards of the developed world. The filters also would be useful in rural areas of developed countries such as the United States where people rely on untreated well water.

Smith noted that U.Va. Architecture School professor Anselmo Canfora and his students have worked closely with PureMadi to design sustainable filter factories for developing countries that would optimize use of local labor and materials.

The National Science Foundation, the National Institutes of Health, U.Va.’s Jefferson Public Citizen Program and the Vice Provost for Global Affairs provide support to PureMadi. Partners include the University of Venda in South Africa; Potters for Peace, a nonprofit organization committed to providing safe drinking water in the developing world; and local communities in Limpopo province in South Africa.

Taken in conjunction with my Feb. 28, 2013 posting titled, Silver nanoparticles, water, the environment, and toxicity, where I juxtaposed two articles about toxicity and silver nanoparticles (they’re ok/they’re not ok) to illustrate the complexity surrounding the question of risk, this article which features silver (and copper) nanoparticles in use for water purification adds another dimension to the question. What are the risks?, to add, are they worth taking?

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Posted in environment, health and safety, nanotechnology, risk | No Comments »

Silver nanoparticles, water, the environment, and toxicity

Thursday, February 28th, 2013

I am contrasting two very different studies on silver nanoparticles in water and their effect on the environment to highlight the complex nature of determining the risks and environmental effects associated with nanoparticles in general. One piece of research suggests that silver nanoparticles are less dangerous than other commonly used forms of silver while the other piece raises some serious concerns.

A Feb. 28, 2013 news item on Nanowerk features research about the effects that silver nanoparticles have on aquatic ecosystems (Note: A link has been removed),

According to Finnish-Estonian joint research with data obtained on two crustacean species, there is apparently no reason to consider silver nanoparticles more dangerous for aquatic ecosystems than silver ions.

The results were reported in the journal Environmental Science and Pollution Research late last year (“Toxicity of two types of silver nanoparticles to aquatic crustaceans Daphnia magna and Thamnocephalus platyurus”). Jukka Niskanen has utilised the same polymerisation and coupling reactions in his doctoral dissertation studying several hybrid nanomaterials, i.e. combinations of synthetic polymers and inorganic (gold, silver and montmorillonite) nanoparticles. Niskanen will defend his doctoral thesis at the University of Helsinki in April.

The University of Helsikinki Feb. 28, 2013 press release written by Minna Merilainen and which originated the new item provides details about the research,

“Due to the fact that silver in nanoparticle form is bactericidal and also fungicidal and also prevents the reproduction of those organisms, it is now used in various consumer goods ranging from wound dressing products to sportswear,” says Jukka Niskanen from the Laboratory of Polymer Chemistry at the University of Helsinki, Finland.A joint study from the University of Helsinki and the National Institute of Chemical Physics and Biophysics (Tallinn, Estonia), Toxicity of two types of silver nanoparticles to aquatic crustaceans Daphnia magna and Thamnocephalus platyurus, shows that silver nanoparticles are apparently no more hazardous to aquatic ecosystems than a water-soluble silver salt. The study compared the ecotoxicity of silver nanoparticles and a water-soluble silver salt.

“Our conclusion was that the environmental risks caused by silver nanoparticles are seemingly not higher than those caused by a silver salt. However, more research is required to reach a clear understanding of the safety of silver-containing particles,” Niskanen says.

Indeed, silver nanoparticles were found to be ten times less toxic than the soluble silver nitrate - a soluble silver salt used for the comparison.

The bioavailability of silver varies in different test media

To explain this phenomenon, the researchers refer to the variance in the bioavailability of silver to crustaceans in different tested media.

University lecturer Olli-Pekka Penttinen from the Department of Environmental Sciences of the University of Helsinki goes on to note that the inorganic and organic compounds dissolved in natural waters (such as humus), water hardness and sulfides have a definite impact on the bioavailability of silver. Due to this, the toxicity of both types of tested nanoparticles and the silver nitrate measured in the course of the study was lower in natural water than in artificial fresh water.

The toxicity of silver nanoparticles and silver ions was studied using two aquatic crustaceans, a water flea (Daphnia magna) and a fairy shrimp ( Thamnocephalus platyurus). Commercially available protein-stabilised particles and particles coated with a water-soluble, non-toxic polymer, specifically synthesised for the purpose, were used in the study. First, the polymers were produced utilising a controlled radical polymerization method. Synthetic polymer-grafted silver particles were then produced by attaching the water-soluble polymer to the surface of the silver with a sulfur bond.

Jukka Niskanen has utilised such polymerisation and coupling reactions in his doctoral dissertation. Polymeric and hybrid materials: polymers on particle surfaces and air-water interfaces, studying several hybrid nanomaterials , i.e., combinations of synthetic polymers and inorganic (gold, silver and montmorillonite) nanoparticles....

It was previously known from other studies and research results that silver changes the functioning of proteins and enzymes. It has also been shown that silver ions can prevent the replication of DNA. Concerning silver nanoparticles, tests conducted on various species of bacteria and fungi have indicated that their toxicity varies. For example, gram-negative bacteria such as Escherichia coli are more sensitive to silver nanoparticles than gram-positive ones (such as Staphylococcus aureus). The difference in sensitivity is caused by the structural differences of the cell membranes of the bacteria. The cellular toxicity of silver nanoparticles in mammals has been studied as well. It has been suggested that silver nanoparticles enter cells via endocytosis and then function in the same manner as in bacterial cells, damaging DNA and hindering cell respiration. Electron microscope studies have shown that human skin is permeable to silver nanoparticles and that the permeability of damaged skin is up to four times higher than that of healthy skin.

While this Finnish-Estonian study suggests that silver nanoparticles do not have a negative impact on the tested crustaceans in an aquatic environment, there’s a study from Duke University suggests that silver nanoparticles in wastewater which is later put to agricultural use may cause problems. From the Feb. 27, 2013 news release on EurekAlert,

In experiments mimicking a natural environment, Duke University researchers have demonstrated that the silver nanoparticles used in many consumer products can have an adverse effect on plants and microorganisms.

…

The main route by which these particles enter the environment is as a by-product of water and sewage treatment plants. [emphasis] The nanoparticles are too small to be filtered out, so they and other materials end up in the resulting “sludge,” which is then spread on the land surface as a fertilizer.

…

The researchers found that one of the plants studied, a common annual grass known as Microstegium vimeneum, had 32 percent less biomass in the mesocosms treated with the nanoparticles. Microbes were also affected by the nanoparticles, Colman [Benjamin Colman, a post-doctoral fellow in Duke's biology department and a member of the Center for the Environmental Implications of Nanotechnology (CEINT)] said. One enzyme associated with helping microbes deal with external stresses was 52 percent less active, while another enzyme that helps regulate processes within the cell was 27 percent less active. The overall biomass of the microbes was also 35 percent lower, he said.

“Our field studies show adverse responses of plants and microorganisms following a single low dose of silver nanoparticles applied by a sewage biosolid,” Colman said. “An estimated 60 percent of the average 5.6 million tons of biosolids produced each year is applied to the land for various reasons, and this practice represents an important and understudied route of exposure of natural ecosystems to engineered nanoparticles.”

“Our results show that silver nanoparticles in the biosolids, added at concentrations that would be expected, caused ecosystem-level impacts,” Colman said. “Specifically, the nanoparticles led to an increase in nitrous oxide fluxes, changes in microbial community composition, biomass, and extracellular enzyme activity, as well as species-specific effects on the above-ground vegetation.”

As previously noted, these two studies show just how complex the questions of risk and nanoparticles can become.  You can find out more about the Finish-Estonian study,

Toxicity of two types of silver nanoparticles to aquatic crustaceans Daphnia magna and Thamnocephalus platyurus by  Irina Blinova, Jukka Niskanen, Paula Kajankari, Liina Kanarbik, Aleksandr Käkinen, Heikki Tenhu, Olli-Pekka Penttinen, and Anne Kahru. Environmental Science and Pollution Research published November 11, 2012 online

The publisher offers an interesting option for this article. While it is behind a paywall, access is permitted through a temporary window if you want to preview a portion of the article that lies beyond the abstract.

Meanwhile here’s the article by the Duke researchers,

Low Concentrations of Silver Nanoparticles in Biosolids Cause Adverse Ecosystem Responses under Realistic Field Scenario by Benjamin P. Colman, Christina L. Arnaout, Sarah Anciaux, Claudia K. Gunsch, Michael F. Hochella Jr, Bojeong Kim, Gregory V. Lowry,  Bonnie M. McGill, Brian C. Reinsch, Curtis J. Richardson, Jason M. Unrine, Justin P. Wright, Liyan Yin, and Emily S. Bernhardt. PLoS ONE 2013; 8 (2): e57189 DOI: 10.1371/journal.pone.0057189

This article is open access as are all articles published by the Public Library of Science (PLoS) journals.

For anyone interested in the Duke University/CEINT mesocosm project, I made mention of it in an Aug. 15, 2011 posting.

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Posted in agriculture, environment, nanotechnology, risk, water | 1 Comment »

Needles from the Douglas Fir tree to be used in antimicrobial coatings for medical devices

Wednesday, January 2nd, 2013

This Jan. 2, 2013 news item on the Nanotechnology Now website casts a whole new light on Christmas trees, specifically the Douglas Fir,

Chemist Poushpi Dwivedi of MNNIT [Motilal Nehru National Institute of Technology] in Allahabad, India, and colleagues explain that one of the most troubling problems in biomedicine is bacterial infection at the site of implanted medical devices, prosthetics and sensors. They explain that despite advances in sterilization procedures and aseptic measures pathogenic microbes can still invade biomaterials and tissues. The researchers are developing an antimicrobial, self-sterilizing composite material derived from Douglas fir needles that is essentially a silver/chitosan bionanocomposite that can be used to safely coat medical implants and surgical devices to preclude microbial growth.

…

The team has now used an extract from Pseudotsuga menzietii together with silver nitrate solution to generate nanoparticles. These particles can then be readily dispersed in chitosan polymer to make a material that can coat metals and other materials. The plant extract acts as a natural chemical reducing agent to convert the silver ions in the nitrate solution to nanoscopic silver metal particles.

Here’s a citation and link for the journal article,

Potentiality of the plant Pseudotsuga menzietii to combat implant-related infection in the nanoregime by Poushpi Dwivedi; S.S. Narvi; R.P. Tewari in
International Journal of Biomedical Nanoscience and Nanotechnology (IJBNN), Vol. 2, No. 3/4, 2012

The article is behind a paywall.

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Posted in coatings, medicine, nanotechnology | No Comments »

Canada-US Regulatory Cooperation Council’s Nanotechnology Work Plan

Monday, December 3rd, 2012

Thanks for Lynn L. Bergeson for her Dec. 1, 2012 posting on the Nanotechnology Now website for the information about a Nov. 28, 2012 webinar that was held to discuss a Nanotechnology Work Plan developed by the joint Canada-US Regulatory Cooperation Council (or sometimes it’s called the US-Canada Regulatory Cooperation Council),

…

The RCC requested that industry provide more information on the commercial distribution of nanomaterials, as well as more transparency by claiming confidentiality of only that information absolutely critical to market advantage.

To compare risk assessment and risk management practices to highlight and identify best practices, data gaps, and differences between the two jurisdictions, the RCC sought nominations of a nanomaterial substance for a case study. Four nanomaterial substances were nominated: multiwall carbon nanotubes, nanocrystalline cellulose, nano silver, and titanium dioxide. The RCC has selected multiwall carbon nanotubes for the case study. The RCC intends to hold in March 2013 a workshop in Washington, D.C., to discuss information collected to date and approaches moving forward. In spring 2013, the RCC will hold one or two conference calls or webinars to discuss information gathered between countries and the path forward. Finally, in fall 2013, the RCC expects to hold a stakeholder consultation/workshop on results to date.

Here’s some background on the RCC. First announced in February 2011, the RCC had its first ‘stakeholder’ session (attended by approximately 240)  in January 2012 in Washington, DC. where a series of initiatives, including nanotechnology, were discussed (from the US International Trade Administration RCC Stakeholder Outreach webpage),

Agriculture and Food, Session A

  • Perimeter approach to plant protection

Agriculture and Food, Session B

  • Crop protection products

Agriculture and Food, Session C

  • Meat/poultry – equivalency
  • Meat/poultry – certification requirements
  • Meat cut nomenclature

Agriculture and Food, Session D

  • Veterinary drugs
  • Zoning for foreign animal disease

Agriculture and Food, Session E

  • Financial protection to produce sellers

Agriculture and Food, Session F

  • Food safety – common approach
  • Food safety – testing

Road Transport – Motor Vehicles

  • Existing motor vehicle safety standards
  • New motor vehicle safety standards

Air Transport

  • Unmanned aircraft

Transportation

  • Intelligent Transportation Systems

Transportation

  • Dangerous goods means of transportation

Marine Transport

  • Safety and security framework & arrangement for the St. Lawrence Seaway & Great Lakes System
  • Marine transportation security regulations
  • Recreational boat manufacturing standards
  • Standard for lifejackets

Rail Transport

  • Locomotive Emissions
  • Rail Safety Standards

Environment

  • Emission standards for light-duty vehicles

Personal Care Products & Pharmaceuticals

  • Electronic submission gateway
  • Over-the-counter products – common monographs
  • Good manufacturing practices

Occupational Safety Issues

  • Classification & labelling of workplace hazardous chemicals

Nanotechnology

  • Nanotechnology

Led jointly by senior officials from Canada and the United States, the purpose of the various technical review sessions was to seek expert advice and technical input from the approximately 240 stakeholders in attendance.

Since the Jan. 2012 meeting, a Nanotechnology Work Plan has been developed and that’s what was recently discussed at the Nov. 28, 2012 webinar. I did find more on a Canadian government website, Canada’s Economic Action Plan Nanotechnology Work Plan webpage,

Nanotechnology Work Plan

 Canada Leads: Karen Dodds, Assistant Deputy Minister, Science and Technology Branch, Environment Canada (EC)

Hilary Geller, Assistant Deputy Minister, Healthy Environments and Consumer Safety Branch, Health Canada (HC)

U.S. Lead: Margaret Malanoski, Office of Information and Regulatory Affairs, Office of Management and Budget

Deliverable Outcome: Share information and develop common approaches, to the extent possible, on foundational regulatory elements, including criteria for determining characteristics of concern/no concern, information gathering, approaches to risk assessment and management, etc. Develop joint initiatives to align regulatory approaches in specific areas such that consistency exists for consumers and industry in Canada and the US.

Principles: Identification of common principles for the regulation of nanomaterials to help ensure consistency for industry and consumers in both countries

3-6 months:

Canada provides initial feedback on US “Policy Principles for the US Decision-Making Concerning Regulation and Oversight of Applications of Nanotechnology and Nanomaterials”.

6-12 months:

Countries complete an initial draft of shared principles for the regulation of nanomaterials.

12-18 months:

Update of draft principles informed from on-going stakeholder and expert consultations.

18th month:

Stakeholder consultation / workshop on results to date and future ongoing engagement.

Beyond 18 months:

Countries complete final draft of shared principles for the regulation of nanomaterials.

Workplan for Industrial Nanomaterials

Priority-Setting: Identify common criteria for determining characteristics of industrial nanomaterials of concern/no-concern

1-3 months:

  1. Define and finalize workplan (1st month)
  2. Develop mechanisms for stakeholder outreach and engagement (1st month)
  3. Conference call with relevant stakeholders to share and discuss workplan and call for Industry to volunteer nanomaterials for joint CAN/US review

3-6 months:

Share available scientific evidence regarding characteristics of industrial nanomaterials including that obtained from existing international fora (e.g. OECD Working Party on Manufactured Nanomaterials [Canada is a lead in the OECD Working Party on Manufactured Nanomaterials]).

8th month:

Stakeholder workshop to discuss information collected to date and approaches moving forward.

6-12 months:

Initiate an analysis of characteristics of select nanomaterials: similarities, differences, reasons for them.

Initiate discussions on approaches to consider for common definitions and terminology.

12th month:

Second conference call with relevant stakeholders to discuss non-CBI information gathered between the Countries and to discuss path forward in terms of development of reports and analyses.

12-18 months:

Develop draft criteria for determining characteristics of industrial nanomaterials of concern/no-concern.

15th month:

Third conference call with relevant stakeholders to discuss progress and to prepare for the upcoming stakeholder consultation/workshop.

…

Here’s information for the leads should you feel compelled to make contact,

Canada

(Lead) Karen Dodds, Assistant Deputy Minister, Science and Technology, Environment Canada (karen.dodds@ec.gc.ca; ph. 613- 819-934-6851)

Hilary Geller, Assistant Deputy Minister, Healthy Environments and Consumer Safety Branch (hilary.geller@hc-sc.gc.ca; ph. 613-946-6701)

United States

(Lead) Margaret Malanoski, Office of Management and Budget (Margaret_A._Malanoski@omb.eop.gov)

I gather that the ‘stakeholders’ are business people, researchers, and policy analysts/makers as there doesn’t seem to be any mechanism for public consultation or education, for that matter.

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Tata Swach and its jaunty silver nanoparticle water purifier advertising campaign

Monday, November 19th, 2012

The Nov. 19, 2012 news item on the Best Media Info Bureau website includes this advertisement which started airing on Indian television on Nov. 17, 2012,

Here’s a little more about the advertising campaign (from the news item),

Tata Swach Nanotech Water Purifier has launched a new ad campaign that emphasises on silver’s antibacterial qualities. The campaign showcases the advanced silver nanotechnology used by Tata Swach to enhance silver’s purification power without any use of harmful chemicals. The TV commercial has been created by DraftFCB+Ulka.

The TVC [television commercial?] began airing on major channels, including high impact properties, from November 17, 2012. The ad campaign will be carried across television, print, radio, online and social media platforms.

There is some mention of safety but it is focused on how silver nanoparticles make the water safer from bacteria and viruses and there’s no hint that there are concerns the nanoparticles themselves might present a problem.

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Looking blue? Maybe it’s silver nanoparticles

Tuesday, October 30th, 2012

Looking blue can mean feeling sad or it can indicate that you have argyria, a condition caused by ingesting too much silver. An Oct. 29, 2012 news item on Nanowerk about research on argyria taking place at Brown University reveals the latest insight on the cause for this condition,

Researchers from Brown University have shown for the first time how ingesting too much silver can cause argyria, a rare condition in which patients’ skin turns a striking shade of grayish blue.

“It’s the first conceptual model giving the whole picture of how one develops this condition,” said Robert Hurt, professor of engineering at Brown and part of the research team. “What’s interesting here is that the particles someone ingests aren’t the particles that ultimately cause the disorder.”

Scientists have known for years argyria had something to do with silver. The condition has been documented in people who (ill advisedly) drink antimicrobial health tonics containing silver nanoparticles and in people who have had extensive medical treatments involving silver. Tissue samples from patients showed silver particles actually lodged deep in the skin, but it wasn’t clear how they got there.

As it turns out, argyria is caused by a complex series of chemical reactions, Hurt said. His paper on the subject, authored with Brown colleagues Jingyu Liu, Zhongying Wang, Frances Liu, and Agnes Kane, is published in the journal ACS Nano (“Chemical Transformations of Nanosilver in Biological Environments” [behind a paywall]).

The Oct. 25, 2012 Brown University news release (which originated the news item) provides more detail,

Hurt and his team have been studying the environmental impact of silver, specifically silver nanoparticles, for years. They’ve found that nanosilver tends to corrode in acidic environments, giving off charged ions — silver salts — that can be toxic in large amounts. Hurt’s graduate student, Jingyu Liu (now a postdoctoral fellow at the National Institute of Standards and Technology), thought those same toxic ions might also be produced when silver enters the body, and could play a role in argyria.

To find out, the researchers mixed a series chemical treatments that could simulate what might happen to silver inside the body. One treatment simulated the acidic environment in the gastrointestinal tract; one mimicked the protein content of the bloodstream; and a collagen gel replicated the base membranes of the skin.

They found that nanosilver corrodes in stomach acid in much the same way it does in other acidic environments. Corrosion strips silver atoms of electrons, forming positively charged silver salt ions. Those ions can easily be taken into the bloodstream through channels that absorb other types of salt. That’s a crucial step, Hurt said. Silver metal particles themselves aren’t terribly likely to make it from the GI tract to the blood, but when they’re transformed into a salt, they’re ushered right through.

From there, Hurt and his team showed that silver ions bind easily with sulfur present in blood proteins, which would give them a free ride through the bloodstream. Some of those ions would eventually end up in the skin, where they’d be exposed to light.

To re-create this end stage, the researchers shined ultraviolet light on collagen gel containing silver ions. The light caused electrons from the surrounding materials to jump onto the unstable ions, returning them to their original state — elemental silver. This final reaction is ultimately what turns patients’ skin blue. The photoreaction is similar to the way silver is used in black and white photography [emphasis mine]. When exposed to light, silver salts on a photographic film reduce to elemental silver and darken, creating an image.

While I find the notion that the body’s reaction to silver is similar to the processing of silver in black and white photography, it’s the discussion about toxicity that most interests me. The scientists at Brown are suggesting that   standard ‘ingestable’ silver could be more dangerous than silver nanoparticles when they are consumed in the body,

This research, however, “would be one piece of evidence that you could treat nanoparticles in the same way as other forms of silver,” Hurt says.

That’s because the bioavailable form of silver — the form that is absorbed into the bloodstream — is the silver salt that’s made in the stomach. Any elemental silver that’s ingested is just the raw material to make that bioavailable salt. So ingesting silver in any form, be it nano or not, would have basically the same effect, Hurt said.

“The concern in this case is the total dose of silver, not what form it’s in,” Hurt said. “This study implies that silver nanoparticles will be less toxic than an equivalent amount of silver salt, at least in this exposure scenario [emphasis mine].”

This research provides more evidence supporting Dr. Andrew Maynard’s contention that creating definitions and regulations for nanomaterials based on size may not be the best approach. Here’s his response to my question (in an Oct. 24, 2011 posting) about the then newly adopted Health Canada definition (which includes size) for nanomaterials,

The problem is that, while the Health Canada is a valiant attempt to craft a definition based on the current state of science, it is still based on a premise – that size within a well defined range is a robust indicator of novel risk – that is questionable [emphasis mine].  Granted, they try to compensate for the limitations of this premise, but the result still smacks of trying to shoehorn the science into an assumption of what is important.

One can only wait as the evidence continues to mount on one side or the other. In the meantime, I don’t one can ever go wrong with BB King, one of the great blues guitar players (Blues Boys Tune),

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Strawberries, silver nanoparticles, and whipped cream

Friday, July 13th, 2012

You can hold the whipped cream and strawberries (save them for a dessert) as you process silver nanoparticles using strawberry tree leaves in an environmentally friendly fashion. From the July 11, 2012 news release on EurekAlert,

Strawberry tree leaf (Arbutus unedo) and silver nitrate (AgNO3). With just these two ingredients scientists can now produce silver nanoparticles, a material that is used in advanced technologies from compounds for distributing medicines through to electronic devices, catalysts, contaminant solvents.

The technique has been developed by scientists at the Aristotle University of Thessaloniki (Greece) and Madrid’s Carlos III University (UC3M) and consists of adding an extract of the leaf to a silver nitrate aqueous solution. Silver nanoparticles form immediately after stirring the mixture for some minutes.

“There are other methods for producing them but this process is the most simple, low cost and easy to implement given that a non-toxic plant is used at a temperature of between 25ºC and 80ºC”, outlines Sophia Tsipas, UC3M researcher and coauthor of the study, which is published on the Materials Letters journal.

Tsipas offers more details about the ability to control particle size and geometry,

Tsipas adds that “the innovation of this method lies in the fact that it allows us to control the parameters for obtaining nanoparticles of a known size (from 5 to 40 nm) and geometry (spheres, pyramids, cubes). The nanoparticles produced remained stable over long periods of time of up to 6 months.”

Strawberry tree leaves facilitate such stability as they form an organic layer of various nanometres around the silver particles. What is more, the extract acts as a reducing agent and stabilizer for the entire product.

The nanoparticles obtained have been characterised and verified with various techniques (transmission electron microscopy, ultraviolet spectroscopy and FTIR). As well as optimising the process, the team is currently studying how to produce similar nanometric sized particles with other metals like gold and copper.

The study has been published,

Pantelis Kouvaris, Andreas Delimitis, Vassilis Zaspalis, Dimitrios Papadopoulos, Sofia A. Tsipas, Nikolaos Michailidis. “Green synthesis and characterization of silver nanoparticles produced using Arbutus Unedo leaf extract”. Materials Letters 76: 18, June 2012. Doi:10.1016/j.matlet.2012.02.025.

For those of us in the Northern Hemisphere, happy summer weekend! We are enjoying strawberry season here in BC, Canada.

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