Tag Archives: silver nanoparticles

Silver nanoparticles and wormwood tackle plant-killing fungus

I’m back in Florida (US), so to speak. Last mentioned here in an April 7, 2015 post about citrus canker and zinkicide, a story about a disease which endangers citrus production in the US, this latest story concerns a possible solution to the problem of a fungus, which attacks ornamental horticultural plants in Florida. From a May 5, 2015 news item on Azonano,

Deep in the soil, underneath more than 400 plant and tree species, lurks a lethal fungus threatening Florida’s $15 billion a year ornamental horticulture industry.

But University of Florida plant pathologist G. Shad Ali has found an economical and eco-friendly way to combat the plant destroyer known as phytophthora before it attacks the leaves and roots of everything from tomato plants to oak trees.

Ali and a team of researchers with UF’s Institute of Food and Agricultural Sciences, along with the University of Central Florida and the New Jersey Institute of Technology, have found that silver nanoparticles produced with an extract of wormwood, an herb with strong antioxidant properties, can stop several strains of the deadly fungus.

A May 4, 2015 University of Florida news release, which originated the news item, describes the work in more detail,

“The silver nanoparticles are extremely effective in eliminating the fungus in all stages of its life cycle,” Ali said. “In addition, it has no adverse effects on plant growth.” [emphasis mine]

The silver nanoparticles measure 5 to 100 nanometers in diameter – about one one-thousandth the width of a human hair. Once the nanoparticles are sprayed onto a plant, they shield it from fungus. Since the nanoparticles display multiple ways of inhibiting fungus growth, the chances of pathogens developing resistance to them are minimized, Ali said. Because of that, they may be used for controlling fungicide-resistant plant pathogens more effectively.

That’s good news for the horticulture industry. Worldwide crop losses due to phytophthora fungus diseases are estimated to be in the multibillion dollar range, with $6.7 billion in losses in potato crops due to late blight – the cause of the Irish Potato Famine in the mid-1800s when more than 1 million people died – and $1 billion to $2 billion in soybean loss.

Silver nanoparticles are being investigated for applications in various industries, including medicine, diagnostics, cosmetics and food processing.  They already are used in wound dressings, food packaging and in consumer products such as textiles and footwear for fighting odor-causing microorganisms.

Other members of the UF research team were Mohammad Ali, a visiting doctoral student from the Quaid-i-Azam University, Islamabad, Pakistan; David Norman and Mary Brennan with the University of Florida’s Plant Pathology-Mid Florida Research and Education Center; Bosung Kim with the University of Central Florida’s chemistry department; Kevin Belfield with the College of Science and Liberal Arts at the New Jersey Institute of Technology and the University of Central Florida’s chemistry department.

Ali’s comment about silver nanoparticles not having any adverse effects on plant growth is in contrast to findings by Mark Wiesner and other researchers at  Duke University (North Carolina, US). From my Feb. 28, 2013 posting (which also features a Finnish-Estonia study showing no adverse effects from silver nanoparticles  in crustaceans),

… 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.”

Getting back to Florida, you can find Ali’s abstract here,

Inhibition of Phytophthora parasitica and P. capsici by silver nanoparticles synthesized using aqueous extract of Artemisia absinthium by Mohammad Ali, Bosung Kim, Kevin Belfield, David J. Norman, Mary Brennan, & Gul Shad Ali. Phytopathology  http://dx.doi.org/10.1094/PHYTO-01-15-0006-R Published online April 14, 2015

This paper is behind a paywall.

For anyone who recognized that wormwood is a constituent of Absinthe, a liquor that is banned in many parts of the world due to possible side effects associated with the wormwood, here’s more about it from the Wormwood overview page on WebMD (Note: Links have been removed),

Wormwood is an herb. The above-ground plant parts and oil are used for medicine.

Wormwood is used in some alcoholic beverages. Vermouth, for example, is a wine beverage flavored with extracts of wormwood. Absinthe is another well-known alcoholic beverage made with wormwood. It is an emerald-green alcoholic drink that is prepared from wormwood oil, often along with other dried herbs such as anise and fennel. Absinthe was popularized by famous artists and writers such as Toulouse-Lautrec, Degas, Manet, van Gogh, Picasso, Hemingway, and Oscar Wilde. It is now banned in many countries, including the U.S. But it is still allowed in European Union countries as long as the thujone content is less than 35 mg/kg. Thujone is a potentially poisonous chemical found in wormwood. Distilling wormwood in alcohol increases the thujone concentration.

Returning to the matter at hand, as I’ve noted previously elsewhere, research into the toxic effects associated with nanomaterials (e.g. silver nanoparticles) is a complex process.

MMA (mixed martial arts) and nano silver wound dressings

I had never, ever expected to mention mixed martial arts (MMA) here but that’s one of the delightful aspects of writing about nanotechnology; you never know where it will take you. A March 9, 2015 news item on Azonano describes the wound situation for athletes and a new product,

..

As an MMA Champion athlete, Rich Franklin knows all too well about germs and how easily they spread. During training he dealt with them on a regular basis, but it wasn’t until the first time he had staph, did he realize these infections could cost him a victory. Now, working in a global setting, Franklin trains in locations around the world which leaves him exposed to a plethora of bacteria and fungi. So he teamed up with American Biotech Labs (ABL) to develop Armor Gel, nano silver-based, wound dressing gel that can stay active on the skin for up to seventy-two hours (3 days). Using patented nano silver technology, Armor Gel has been scientifically tested to reduce the levels of bacteria and other pathogens, while forming a protective barrier “armor” over the wound. By shielding the body from external bacterial, the body’s natural healing process can be expedited. Its use is recommended by doctors, trainers, coaches, and athletes alike.

A March 6, 2015 ABL news release on BusinessWire, which originated the news item, provides a little more detail about Armor Gel,

Engineered for today’s modern athletes, Armor Gel is safe, nontoxic and provides a personal first line of defense. Already proven to reduce the levels of MRSA, VRE, pseudomonas aeruginosa, E. coli, A. niger and Candida albicans, Armor Gel is formulated using a unique and patented 24 SilverSol Technology®.

American Biotech Labs (ABL) was started in 2002 as a nano silver biotech company with the goal of creating a more stable and powerful silver technology for consumer products. …

I am providing a link to the product website (neither the link nor this post are endorsements), you can find out more about Armor Gel here.

Armor Gel was announced previously in a Sept. 16, 2014 ABL news release on PR Newswire, At the time no mention was made of Rich Franklin, their MMA athlete,

American Biotech Labs, LLC, is pleased to announce the availability of three new silver hydrogel wound-dressing products.  The new products will allow American Biotech Labs (ABL) to market in the wound-care market focusing on ultimate sports and fitness, spa and health, and animal markets.

The new over-the-counter (OTC) products will have wound-dressing claims for minor cuts, lacerations, abrasions, 1st and 2nd degree burns, and skin irritations.  The products also have pathogen-inhibiting barrier claims against pathogens, such as Staphylococcus aureus, Pseudomonas aeruginosa, Escherichia coli, MRSA and VRE, as well as fungi, such as Candida albicans and Aspergillus niger.  These new gels can provide a barrier that will help protect wounds for 24 to 72 hours.

The new products will be found under the names of Armor Gel™ (for the ultimate sports and fitness market), ASAP OTC™ (for the spa and health markets), and ASAP Pet Shield® (for the animal market).

Along with the release of these new products, ABL has formed a strategic alliance with Stuart Evey, founder and former chairman of ESPN, and Gary Bernstein, marketing executive and professional photographer and film maker.  ABL will utilize these talented individuals to help introduce these revolutionary new products to high-profile organizations in sports, pet stores, fashion and beauty, medical, and direct-marketing areas, etc.

Said Keith Moeller, ABL Director, “We are very grateful to the numerous top scientists, labs and universities that have helped move this amazing, patented, silver technology forward.  We believe that these products have the ability to impact the future of wound management worldwide.”

Note: Any statements released by American Biotech Labs, LLC that are forward looking are made pursuant to the safe harbor provisions of the Private Securities Litigation Reform Act of 1995.  Editors and investors are cautioned that forward looking statements invoke risk and uncertainties that may affect the company’s business prospects and performance.

You can find out more about ABL and its entire product line here.

Silver nanoparticle reference materials

When comparing silver nanoparticle toxicity studies, it would be good to know that the studies are all looking at the same type of nanoparticle. Happily, the US National Institute of Standards and Technology (NIST) has developed a silver nanoparticle reference material for just that purpose. From a March 5, 2015 news item on Azonano,

The National Institute of Standards and Technology (NIST) has issued a new silver nanoparticle reference material to support researchers studying potential environmental, health and safety risks associated with the nanoparticles, which are being incorporated in a growing number of consumer and industrial products for their antimicrobial properties. The new NIST test material is believed to be the first of its kind to stabilize the highly reactive silver particles in a freeze-dried, polymer coated, nanoparticle cake for long-term storage.

Nanoparticulate silver is a highly effective bactericide. It is, by some estimates, the most widely used nanomaterial in consumer products. These include socks and shoe liners (it combats foot odor), stain-resistant fabrics, coatings for handrails and keyboards, and a plethora of other applications.

The explosion of “nanosilver” products has driven a like expansion of research to better understand what happens to the material in the environment. “Silver nanoparticles transform, dissolve and precipitate back into nanoparticles again, combine or react with other materials—our understanding of these processes is limited,” says NIST chemist Vince Hackley. “However, in order to study their biological and environmental behavior and fate, one needs to know one is starting with the same material and not some modified or oxidized version. This new reference material targets a broad range of research applications.” [emphasis mine]

A March 3, 2015 NIST news release, which originated the news item, elaborates,

Silver nanoparticles are highly reactive. In the presence of oxygen or moisture they rapidly oxidize, subsequently releasing silver ions. This is the basis for their antimicrobial properties, but it also makes it difficult to create a standardized silver nanoparticle suspension with a long shelf life as a basis for doing comparative environmental studies. The new NIST product is the first to be stabilized by coating and freeze-drying—a technique commonly used in the pharmaceutical industry to preserve blood products and protein-based drugs. The NIST material uses polyvinylpyrrolidone (PVP), a polymer approved by the Food and Drug Administration for many uses, including as a food additive. The freeze-dried PVP-nanosilver cakes are flushed with an inert gas and sealed under a vacuum. Mixing the cake with water reconstitutes the original suspension.

NIST reference materials are designed to be homogeneous and stable. NIST provides the best available estimates for key properties of reference materials. In this case those include the mean silver particle size measured by four different methods, the total silver mass per vial, and the percentage distribution of nanoparticle sizes. The particles have a nominal diameter of 75 nanometers. NIST expects the material to be stable indefinitely when properly stored and handled, but will continue to monitor it for substantive changes in the reported values.

More information on NIST RM 8017, “Polyvinylpyrrolidone Coated Silver Nanoparticles” is available at https://www-s.nist.gov/srmors/view_report.cfm?srm=8017.

Given this development, I’m beginning to question all of the silver studies I’ve seen previously.

Nanoparticles in 3D courtesy of x-rays

A Feb. 4, 2015 Deutsches Elektronen-Synchrotron (DESY) press release (also on EurekAlert) announces a 3D first,

For the first time, a German-American research team has determined the three-dimensional shape of free-flying silver nanoparticles, using DESY’s X-ray laser FLASH. The tiny particles, hundreds of times smaller than the width of a human hair, were found to exhibit an unexpected variety of shapes, as the physicists from the Technical University (TU) Berlin, the University of Rostock, the SLAC National Accelerator Laboratory in the United States and from DESY report in the scientific journal Nature Communications. Besides this surprise, the results open up new scientific routes, such as direct observation of rapid changes in nanoparticles.

The press release goes on to describe the work in more detail,

“The functionality of nanoparticles is linked to their geometric form, which is often very difficult to determine experimentally,” explains Dr. Ingo Barke from the University of Rostock. “This is particularly challenging when they are present as free particles, that is, in the absence of contact with a surface or a liquid.”

The nanoparticle shape can be revealed from the characteristic way how it scatters X-ray light. Therefore, X-ray sources like DESY’s FLASH enable a sort of super microscope into the nano-world. So far, the spatial structure of nanoparticles has been reconstructed from multiple two-dimensional images, which were taken from different angles. This procedure is uncritical for particles on solid substrates, as the images can be taken from many different angles to uniquely reconstruct their three-dimensional shape.

“Bringing nanoparticles into contact with a surface or a liquid can significantly alter the particles, such that you can no longer see their actual form,” says Dr. Daniela Rupp from the TU Berlin. A free particle, however, can only be measured one time in flight before it either escapes or is destroyed by the intense X-ray light. Therefore, the scientists looked for a way to record the entire structural information of a nanoparticle with a single X-ray laser pulse.

To achieve this goal, the scientists led by Prof. Thomas Möller from the TU Berlin and Prof. Karl-Heinz Meiwes-Broer and Prof. Thomas Fennel from the University of Rostock employed a trick. Instead of taking usual small-angle scattering images, the physicists recorded the scattered X-rays in a wide angular range. “This approach virtually captures the structure from many different angles simultaneously from a single laser shot,” explains Fennel.

The researchers tested this method on free silver nanoparticles with diameters of 50 to 250 nanometres (0.00005 to 0.00025 millimetres). The experiment did not only verify the feasibility of the tricky method, but also uncovered the surprising result that large nanoparticles exhibit a much greater variety of shapes than expected.

The shape of free nanoparticles is a result of different physical principles, particularly the particles’ effort to minimize their energy. Consequently, large particles composed of thousands or millions of atoms often yield predictable shapes, because the atoms can only be arranged in a particular way to obtain an energetically favourable state.

In their experiment, however, the researchers observed numerous highly symmetrical three-dimensional shapes, including several types known as Platonic and Archimedean bodies. Examples include the truncated octahedron (a body consisting of eight regular hexagons and six squares) and the icosahedron (a body made up of twenty equilateral triangles). The latter is actually only favourable for extremely small particles consisting of few atoms, and its occurrence with free particles of this size was previously unknown. “The results show that metallic nanoparticles retain a type of memory of their structure, from the early stages of growth to a yet unexplored size range,” emphasizes Barke.

Due to the large variety of shapes, it was especially important to use a fast computational method so that the researchers were capable of mapping the shape of each individual particle. The scientists used a two-step process: the rough shape was determined first and then refined using more complex simulations on a super computer. This approach turned out to be so efficient that it could not only determine various shapes reliably, but could also differentiate between varying orientations of the same shape.

This new method for determining the three-dimensional shape and orientation of nanoparticles with a single X-ray laser shot opens up a wide spectrum of new research directions. In future projects, particles could be directly “filmed” in three dimensions during growth or during phase changes. “The ability to directly film the reaction of a nanoparticle to an intense flash of X-ray light has been a dream for many physicists – this dream could now come true, even in 3D!,” emphasises Rupp.

The researchers have provided an image showing their work,

Caption: This is a wide-angle X-ray diffraction image of a truncated twinned tetrahedra nanoparticle. Credit: Hannes Hartmann/University of Rostock

Caption: This is a wide-angle X-ray diffraction image of a truncated twinned tetrahedra nanoparticle.
Credit: Hannes Hartmann/University of Rostock

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

The 3D-architecture of individual free ​silver nanoparticles captured by X-ray scattering by Ingo Barke, Hannes Hartmann, Daniela Rupp, Leonie Flückiger, Mario Sauppe, Marcus Adolph, Sebastian Schorb, Christoph Bostedt, Rolf Treusch, Christian Peltz, Stephan Bartling, Thomas Fennel, Karl-Heinz Meiwes-Broer, & Thomas Möller. Nature Communications 6, Article number: 6187 doi:10.1038/ncomms7187 Published 04 February 2015

This article is open access.

Philippe Starck’s luggage goes nano

For anyone unfamiliar with Philippe Starck, there’s this from his Wikipedia entry (Note: Links have been removed),

Philippe Starck is a French designer[1] who has become widely known since the start of his career in the 1980s[2] for his interior, product, industrial and architectural design work.

A minimalist, Starck’s work is ‘stark’. In an interesting publicity campaign, his latest collection of travel gear is mentioned in a Feb. 4, 2015 news item on Nanotechnology Now,

In association with Philippe Starck, renowned French creator, designer and architect, DELSEY is reinventing the world of travel with the launch of STARCKTRIP, a new collection of luggage conceived on a single concept: intelligence in motion. Bold, original and innovative, leaving the fickle constraints of fashion behind to embrace timelessness.

The launch for this line was originally announced in an Oct. 9, 2014 Starck press release which includes a bit about the nanotechnology-enabled features of this luggage,

HIGH TECH DISCRETION
The materials used take advantage of the latest technological innovations but manage to be discrete about it. Nanotechnology is used to protect the bags and
cases, inside and out, from dirt and bacteria; fabric screens also protect against data theft; gentle plastic moulded material provides unparalleled rolling comfort, smoothness and silence. In addition, anti-rain treatment of the surfaces ensures that you, the business traveller, keep your belongings dry at all times. [emphases mine]

I’m not sure about the dirt but the protection from bacteria makes it sound like they’ve added nanoscale silver to the luggage and the anti-rain treatment sounds like a nanotechnology-enabled superhydrophobic coating of some kind. Unfortunately there are no details to be had on either Philippe Starck’s website or on the Delsey website. BTW, the middle-aged male model in the Starck press release, is M. Philippe Starck himself.

Carbohydrates could regulate the toxicity of silver nanoparticles

According to a Jan. 22, 2015 news item on Azonano, you can vary the toxic impact of silver nanoparticles on cells by coating them with carbohydrates,

The use of colloidal silver to treat illnesses has become more popular in recent years, but its ingestion, prohibited in countries like the US, can be harmful to health. Scientists from the Max Planck Institute in Germany have now confirmed that silver nanoparticles are significantly toxic when they penetrate cells, although the number of toxic radicals they generate can vary by coating them with carbohydrates.

A Jan. 21, 2015 Spanish Foundation for the Science and Technology (FECYT) news release on EurekAlert, which originated the news item, describes colloidal silver and its controversies and the research on limiting silver nanoparticle toxicity to cells,

Silver salts have been used externally for centuries for their antiseptic properties in the treatment of pains and as a surface disinfectant for materials. There are currently people who use silver nanoparticles to make homemade potions to combat infections and illnesses such as cancer and AIDS, although in some cases the only thing they achieve is argyria or blue-tinged skin.

Health authorities warn that there is no scientific evidence that supports the therapeutic efficiency of colloidal silver and in fact, in some countries like the US, its ingestion is prohibited. On the contrary, there are numerous studies which demonstrate the toxicity of silver nanoparticles on cells.

One of these studies has just been published in the ‘Journal of Nanobiotechnology‘ by an international team of researchers coordinated from the Max Planck Institute of Colloids and Interfaces (Germany). “We have observed that it is only when silver nanoparticles enter inside the cells that they produce serious harm, and that their toxicity is basically due to the oxidative stress they create,” explains the Spanish chemist Guillermo Orts-Gil, project co-ordinator, to SINC.

To carry out the study, the team has analysed how different carbohydrates act on the surface of silver nanoparticles (Ag-NP) of around 50 nanometres, which have been introduced into cultures of liver cells and tumour cells from the nervous system of mice. The results reveal that, for example, the toxic effects of the Ag-NP are much greater if they are covered with glucose instead of galactose or mannose.

‘Trojan horse’ mechanism

Although not all the details on the complex toxicological mechanisms are known, it is known that the nanoparticles use a ‘Trojan horse’ mechanism to trick the membrane’s defences and get inside the cell. “The new data shows how the different carbohydrate coatings regulate the way in which they do this, and this is hugely interesting for controlling their toxicity and designing future trials,” points out Orts-Gil.

The researcher highlights that there is a “clear correlation between the coating of the nanoparticles, the oxidative stress and toxicity, and thus, these results open up new perspectives on regulating the bioactivity of the Ag-NP through the use of carbohydrates”.

Silver nanoparticles are not only used to make homemade remedies; they are also increasingly used in drugs such as vaccines, as well as products such as clothes and cleaning cloths.

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

Carbohydrate functionalization of silver nanoparticles modulates cytotoxicity and cellular uptake by David C Kennedy, Guillermo Orts-Gil, Chian-Hui Lai, Larissa Müller, Andrea Haase, Andreas Luch, and Peter H Seeberger. Journal of Nanobiotechnology 2014, 12:59 doi:10.1186/s12951-014-0059-z published 19 December 2014

This is an open access paper. One final observation, David Kennedy, the lead author, is associated with both the Max Planck Institute and the Canada National Research Council and, depending on which news release (SINC news site Jan. 20, 2015) you read, Guillermo Orts-Gil is identified as a Spanish chemist and coordinator for SINC (Science News and Information Service).

Singaporeans’ perceptions of nanotechnology and consumer attitudes towards nanotechnologies in food production

This is the first time I’ve seen a study about nanotechnology perception and awareness from Asia. (As I’m sure this is not the first or the only such study, I lament my language skills once more. Since my primary search is for English language materials with my second language, French, as a very distant second, I am limited to translated materials.)

This piece of research comes from Singapore. From a Dec. 11, 2014 news item on the Asian Scientist magazine website,

A survey published in the Journal of Nanoparticle Research shows that while the Singaporean population is more familiar with nanotechnology than their Western counterparts in the US and Europe, they are also more wary of the risks involved.

Asia is expected to dominate the use and release of nanomaterials into the environment, largely due to the size of the population. Furthermore, the region in general—and Singapore in particular—has invested heavily in nanotechnology research, rapidly translating their findings into industrial and consumer products. However, there has been a lack of studies documenting public attitudes and acceptance of new technologies such as nanotechnology.

To address this gap of information, a team of researchers led by first author Dr. Saji George from the Nanyang Polytechnic (NYP) Center for Sustainable Nanotechnology conducted a survey of 1,080 Singaporeans above the age of 15. Their results revealed that approximately 80 percent had some understanding of nanotechnology.

A June 20, 2014 Nanyang Polytechnic media release provides additional details about the research,

In a recent public perception study conducted in Singapore with 1,000 respondents, researchers from Nanyang Polytechnic’s (NYP) Centre for Sustainable Nanotechnology (CSN) found that 80% of respondents were aware of nanotechnology, while only 40% of them were positive about its benefits. This was shared at the official launch of the CSN today. The event was graced by Mr Derek Ho, Director-General, Environmental Public Health Division, National Environment Agency (NEA).

The Centre is the first-of-its-kind among institutes of higher learning (IHLs) in Singapore. It is dedicated to studying the potential impact of novel engineered nanomaterials, and developing ways to ensure that nanotechnology applications are adopted in a sustainable manner for individuals and the environment. This makes the $1 million facility a key training facility for NYP’s students from the Schools of Chemical & Life Sciences, Engineering, and Health Sciences.

Perceptions influenced by exposure to prior information

The perception study conducted in collaboration with the United Kingdom’s Newcastle University, is part of a worldwide study. [emphasis mine] About 1,000 respondents were surveyed in Singapore. Among them, 80% had some level of familiarity with nanotechnology,  while only 40% of them were positive about its benefits. One of the strong determinants that influenced the perception of the public was their prior exposure to news on adverse effects of nanotechnology. This could be due to negative information on nanotechnology carried in the media. Often these are over interpretations of laboratory studies that tend to dampen public confidence in nanotechnology.

“Nanotechnology may be a double-edged sword in some applications. A large proportion of the population is already aware of it, and interestingly, 60% have actually come across negative information on nanotechnology. This points to the need for the Centre for Sustainable Nanotechnology to conduct its work robustly and effectively, to sharpen the benefits, and blunt the risks associated with nanotechnology. This will enable industries to better apply the relevant solutions, and for people to use products containing nanotechnology more confidently. Another impetus for the Centre is that through such studies, companies will learn what consumers are concerned about in specific types of products and how these concerns can be addressed during product design and manufacturing stages,” said Dr Joel Lee, Director of NYP’s School of Chemical & Life Sciences where the Centre is located.

The study also found variations in perception among different socio-demographic groups, and among applications of nanotechnology across different product ranges, for example food, baby products, medicine, clothing, cosmetics, water filters and electronics.

While this is a segue, there’s a very interesting tidbit about silver nanoparticles in this media release,

Smarter Antibacterial Nanotechnology

Since the CSN started operations in 2013, senior lecturers, Dr Saji George and Dr Hannah Gardner, from NYP’s Schools of Chemical & Life Sciences and Engineering, respectively, have studied the effectiveness of nano-silver in eliminating bacteria – which accounts for 30% of commercial nanotechnology – in applications currently available in the market. Nano-silver is largely used as an alternate anti-microbial solution in a range of industries, including clothing, baby products, personal care products and medicine.

Their research findings, now filed as a patent, uncovered that some drug resistant bacterial strains could also develop resistance to silver, contrary to the general notion that all bacterial strains will succumb to it. The duo then designed and developed a cost-effective method to generate cationic polymer coated silver nanoparticles. They observed that these nanoparticles could eliminate pathogenic bacteria regardless of their ability to resist antibiotics and silver.

Dr Lee added, “Nano-silver has captured the attention of industry and researchers. What we hope to achieve with the CSN is two-fold. We aim to be a resource for industries and even government regulatory agencies to tap on to better understand nanotechnology, its effects, and improve on its applications. These would also translate into real-world industry projects for our students and equip them to better serve the industry when they embark on their careers.”

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

Awareness on adverse effects of nanotechnology increases negative perception among public: survey study from Singapore by Saji George, Gulbanu Kaptan, Joel Lee, Lynn Frewer. Journal of Nanoparticle Research November 2014, 16:2751 Date: 22 Nov 2014

This paper is behind a paywall.

I did search for the “… worldwide study” regarding nanotechnology awareness and perceptions but found instead a recently published study on the topic of consumer attitudes towards nanotechnologies used in food production practices which features George and Frewer,

Consumer attitudes towards nanotechnologies applied to food production by L.J. Frewer, N. Gupta, S. George, A.R.H. Fischer, E.L. Giles, and D. Coles. Trends in Food Science & Technology, Volume 40, Issue 2, December 2014, Pages 211–225 (Special Issue: Nanotechnology in Foods: Science behind and future perspectives)

This article is behind a paywall.

rePOOPulate, silver nanoparticles, your gut, and Queen’s University (Canada)

A Nov. 19, 2014 Queen’s University (Ontario, Canada) news release by Anne Craig (also on EurekAlert), describes some research into nanosilver’s effects on the human (more or less) gut,

Queen’s University biologist Virginia Walker and Queen’s SARC Awarded Postdoctoral Fellow Pranab Das have shown nanosilver, which is often added to water purification units, can upset your gut. The discovery is important as people are being exposed to nanoparticles every day.

“We were surprised to see significant upset of the human gut community at the lowest concentration of nanosilver in this study,” says Dr. Das. “To our knowledge, this is the first time anyone has looked at this. It is important as we are more and more exposed to nanoparticles in our everyday lives through different routes such as inhalation, direct contact or ingestion.”

To conduct the research, Drs. Walker and Das utilized another Queen’s discovery, rePOOPulate, created by Elaine Petrof (Medicine). rePOOPulate is a synthetic stool substitute, which Dr. Petrof designed to treat C. difficile infections. In this instance, rather than being used as therapy, the synthetic stool was used to examine the impact of nanoparticles on the human gut.

The research showed that the addition of nanosilver reduced metabolic activity in the synthetic stool sample, perturbed fatty acids and significantly changed the population of bacteria. This information can help lead to an understanding of how nanoparticles could impact our “gut ecosystem.” [emphasis mine]

“There is no doubt that the nanosilver shifted the bacterial community, but the impact of nanosilver ingestion on our long-term health is currently unknown,” Dr. Walker says. “This is another area of research we need to explore.”

The findings by Drs. Das and Walker, Julie AK McDonald (Kingston General Hospital), Dr. Petrof (KGH)  and Emma Allen-Vercoe (University of Guelph) were published in the Journal of Nanomedicine and Nanotechnology.

It’s perturbing news. And, I notice the news release is carefully worded, “This information can help lead to an understanding of how nanoparticles could impact our ‘gut ecosystem.'”

The news release notes this about the ubiquity of nanosilver use,

Nanosilver is also used in biomedical applications, toys, sunscreen, cosmetics, clothing and other items.

I’m a little surprised by the reference to sunscreens; most of the material I’ve seen cites titanium dioxide and/or zinc oxide at the nanoscale.

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

Nanosilver-Mediated Change in Human Intestinal Microbiota by Pranab Das, Julie AK McDonald, Elaine O Petrof, Emma Allen-Vercoe, and Virginia K Walker. Nanomed Nanotechnol 5: 235. doi: 10.4172/2157-7439.1000235

The link takes you to a PDF version of the research paper,

Note: Queen’s University is located in Kingston, Ontario, Canada.

Fewer silver nanoparticles washed off coated textiles

This time I have two complementary tidbits about silver nanoparticles, their use in textiles, and washing. The first is a June 30, 2014 news item on Nanowerk, with the latest research from Empa (Swiss Federal Laboratories for Materials Science and Technology) on silver nanoparticles being sloughed off textiles when washing them,

The antibacterial properties of silver-coated textiles are popular in the fields of sport and medicine. A team at Empa has now investigated how different silver coatings behave in the washing machine, and they have discovered something important: textiles with nano-coatings release fewer nanoparticles into the washing water than those with normal coatings …

A June 30,  2014 Empa news release, which originated the news item, describes the findings in more detail,

If it contains ‘nano’, it doesn’t primarily leak ‘nano': at least that’s true for silver-coated textiles, explains Bernd Nowack of the «Technology and Society» division at Empa. During each wash cycle a certain amount of the silver coating is washed out of the textiles and ends up in the waste water. [emphasis mine] Empa analysed this water; it turned out that nano-coated textiles release hardly any nano-particles. That’s quite the opposite to ordinary coatings, where a lot of different silver particles were found. Moreover, nano-coated silver textiles generally lose less silver during washing. This is because considerably less silver is incorporated into textile fabrics with nano-coating, and so it is released in smaller quantities for the antibacterial effect than is the case with ordinary coatings. A surprising result that has a transformative effect on future analyses and on the treatment of silver textiles. «All silver textiles behave in a similar manner – regardless of whether they are nano-coated or conventionally-coated,» says Nowack. This is why nano-textiles should not be subjected to stricter regulation than textiles with conventional silver-coatings, and this is relevant for current discussions concerning possible special regulations for nano-silver.

But what is the significance of silver particles in waste water? Exposed silver reacts with the (small quantities of) sulphur in the air to form silver sulphide, and the same process takes place in the waste water treatment plant. The silver sulphide, which is insoluble, settles at the bottom of the sedimentation tank and is subsequently incinerated with the sewage sludge. So hardly any of the silver from the waste water remains in the environment. Silver is harmless because it is relatively non-toxic for humans. Even if silver particles are released from the textile fabric as a result of strong sweating, they are not absorbed by healthy skin.

I’ve highlighted Nowack’s name as he seems to have changed his opinions since I first wrote about his work with silver nanoparticles in textiles and washing in a Sept. 8, 2010 posting,

“We found that the total released varied considerably from less than 1 to 45 percent of the total nanosilver in the fabric and that most came out during the first wash,” Bernd Nowack, head of the Environmental Risk Assessment and Management Group at the Empa-Swiss Federal Laboratories for Materials Testing and Research, tells Nanowerk. “These results have important implications for the risk assessment of silver textiles and also for environmental fate studies of nanosilver, because they show that under certain conditions relevant to washing, primarily coarse silver-containing particles are released.”

How did the quantity of silver nanoparticles lost in water during washing change from “less than 1 to 45 percent of the total nanosilver in the fabric” in a 2010 study to “Empa analysed this water; it turned out that nano-coated textiles release hardly any nano-particles” in a 2014 study? It would be nice to find out if there was a change in the manufacturing process and whether or not this is global change or one undertaken in Switzerland alone.

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

Presence of Nanoparticles in Wash Water from Conventional Silver and Nano-silver Textiles by Denise M. Mitrano, Elisa Rimmele, Adrian Wichser, Rolf Erni, Murray Height, and Bernd Nowack. ACS Nano, Article ASAP DOI: 10.1021/nn502228w Publication Date (Web): June 18, 2014

Copyright © 2014 American Chemical Society

This paper is behind a paywall.

The second tidbit is from Iran and may help to answer my questions about the Empa research. According to a July 7, 2014 news item on Nanowerk (Note: A link has been removed),

Writing in The Journal of The Textile Institute (“Effect of silver nanoparticles morphologies on antimicrobial properties of cotton fabrics”), researchers from Islamic Azad University in Iran, describe the best arrangement for increasing the antibacterial properties of textile products by studying various structures of silver nanoparticles.

A July 7, 2014 news release from the Iran Nanotechnology Initiative Council (INIC), which originated the news item, provides more details,

By employing the structure presented by the researchers, the amount of nanoparticles stabilization on the fabric and the durability of its antibacterial properties increase after washing and some problems are solved, including the change in the fabric color.

Using the results of this research creates diversity in the application of various structures of nanoparticles in the complementary process of cotton products. Moreover, the color of the fabric does not change as the amount of consumed materials decreases, because the excess use of silver was the cause of this problem. On the other hand, the stability and durability of nanoparticles increase against standard washing. All these facts result in the reduction in production cost and increase the satisfaction of the customers.

The researchers have claimed that in comparison with other structures, hierarchical structure has much better antibacterial activity (more than 91%) even after five sets of standard washing.

This work on morphology would seem to answer my question about the big difference in Nowack’s description of the quantity of silver nanoparticles lost due to washing. I am assuming, of course, that something has changed with regard to the structure and/or shape of the silver nanoparticles coating the textiles used in the Empa research.

Getting back to the work in Iran, here’s a link to and a citation for the paper,

Effect of silver nanoparticles morphologies on antimicrobial properties of cotton fabrics by Mohammad Reza Nateghia & Hamed Hajimirzababa. The Journal of The Textile Institute Volume 105, Issue 8, 2014 pages 806-813 DOI: 10.1080/00405000.2013.855377 Published online: 21 Jan 2014

This paper is behind a paywall.

Disassembling silver nanoparticles

The notion of self-assembling material is a longstanding trope in the nanotechnology narrative. Scientists at the University of California at Santa Barbara (UCSB) have upended this trope with their work on disassembling the silver nanoparticles being used as a method of delivery for medications. From a June 9, 2014 news item on Azonano,

Scientists at UC Santa Barbara have designed a nanoparticle that has a couple of unique — and important — properties. Spherical in shape and silver in composition, it is encased in a shell coated with a peptide that enables it to target tumor cells. What’s more, the shell is etchable so those nanoparticles that don’t hit their target can be broken down and eliminated. The research findings appear today in the journal Nature Materials.

A june 8, 2014 UCSB news release (also on EurekAlert) by Julie Cohen, which originated the news item, explains the technology and this platform’s unique features in more detail,

The core of the nanoparticle employs a phenomenon called plasmonics. In plasmonics, nanostructured metals such as gold and silver resonate in light and concentrate the electromagnetic field near the surface. In this way, fluorescent dyes are enhanced, appearing about tenfold brighter than their natural state when no metal is present. When the core is etched, the enhancement goes away and the particle becomes dim.

UCSB’s Ruoslahti Research Laboratory also developed a simple etching technique using biocompatible chemicals to rapidly disassemble and remove the silver nanoparticles outside living cells. This method leaves only the intact nanoparticles for imaging or quantification, thus revealing which cells have been targeted and how much each cell internalized.

“The disassembly is an interesting concept for creating drugs that respond to a certain stimulus,” said Gary Braun, a postdoctoral associate in the Ruoslahti Lab in the Department of Molecular, Cellular and Developmental Biology (MCDB) and at Sanford-Burnham Medical Research Institute. “It also minimizes the off-target toxicity by breaking down the excess nanoparticles so they can then be cleared through the kidneys.”

This method for removing nanoparticles unable to penetrate target cells is unique. “By focusing on the nanoparticles that actually got into cells,” Braun said, “we can then understand which cells were targeted and study the tissue transport pathways in more detail.”

Some drugs are able to pass through the cell membrane on their own, but many drugs, especially RNA and DNA genetic drugs, are charged molecules that are blocked by the membrane. These drugs must be taken in through endocytosis, the process by which cells absorb molecules by engulfing them.

“This typically requires a nanoparticle carrier to protect the drug and carry it into the cell,” Braun said. “And that’s what we measured: the internalization of a carrier via endocytosis.”

Because the nanoparticle has a core shell structure, the researchers can vary its exterior coating and compare the efficiency of tumor targeting and internalization. Switching out the surface agent enables the targeting of different diseases — or organisms in the case of bacteria — through the use of different target receptors. According to Braun, this should turn into a way to optimize drug delivery where the core is a drug-containing vehicle.

“These new nanoparticles have some remarkable properties that have already proven useful as a tool in our work that relates to targeted drug delivery into tumors,” said Erkki Ruoslahti, adjunct distinguished professor in UCSB’s Center for Nanomedicine and MCDB department and at Sanford-Burnham Medical Research Institute. “They also have potential applications in combating infections. Dangerous infections caused by bacteria that are resistant to all antibiotics are getting more common, and new approaches to deal with this problem are desperately needed. Silver is a locally used antibacterial agent and our targeting technology may make it possible to use silver nanoparticles in treating infections anywhere in the body.”

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

Etchable plasmonic nanoparticle probes to image and quantify cellular internalization by Gary B. Braun, Tomas Friman, Hong-Bo Pang, Alessia Pallaoro, Tatiana Hurtado de Mendoza, Anne-Mari A. Willmore, Venkata Ramana Kotamraju, Aman P. Mann, Zhi-Gang She, Kazuki N. Sugahara, Norbert O. Reich, Tambet Teesalu, & Erkki Ruoslahti. Nature Materials (2014) doi:10.1038/nmat3982 Published online 08 June 2014

This article is behind a paywall but there is a free preview via ReadCube Access.