Textination Newsline

Reset
6 results
Researchers led by Bernd Nowack have investigated the release of nanoparticles during the washing of polyester textiles. Image: Empa Image: Empa
14.02.2024

Release of oligomers from polyester textiles

When nanoplastics are not what they seem ... Textiles made of synthetic fibers release micro- and nanoplastics during washing. Empa researchers have now been able to show: Some of the supposed nanoplastics do not actually consist of plastic particles, but of water-insoluble oligomers. The effects they have on humans and the environment are not yet well-understood.

Plastic household items and clothing made of synthetic fibers release microplastics: particles less than five millimetres in size that can enter the environment unnoticed. A small proportion of these particles are so small that they are measured in nanometers. Such nanoplastics are the subject of intensive research, as nanoplastic particles can be absorbed into the human body due to their small size – but, as of today, little is known about their potential toxicity.

When nanoplastics are not what they seem ... Textiles made of synthetic fibers release micro- and nanoplastics during washing. Empa researchers have now been able to show: Some of the supposed nanoplastics do not actually consist of plastic particles, but of water-insoluble oligomers. The effects they have on humans and the environment are not yet well-understood.

Plastic household items and clothing made of synthetic fibers release microplastics: particles less than five millimetres in size that can enter the environment unnoticed. A small proportion of these particles are so small that they are measured in nanometers. Such nanoplastics are the subject of intensive research, as nanoplastic particles can be absorbed into the human body due to their small size – but, as of today, little is known about their potential toxicity.

Empa researchers from Bernd Nowack's group in the Technology and Society laboratory have now joined forces with colleagues from China to take a closer look at nanoparticles released from textiles. Tong Yang, first author of the study, carried out the investigations during his doctorate at Empa. In earlier studies, Empa researchers were already able to demonstrate that both micro- and nanoplastics are released when polyester is washed. A detailed examination of the released nanoparticles released has now shown that not everything that appears to be nanoplastic at first glance actually is nanoplastic.

To a considerable extent, the released particles were in fact not nanoplastics, but clumps of so-called oligomers, i.e. small to medium-sized molecules that represent an intermediate stage between the long-chained polymers and their individual building blocks, the monomers. These molecules are even smaller than nanoplastic particles, and hardly anything is known about their toxicity either. The researchers published their findings in the journal Nature Water.

For the study, the researchers examined twelve different polyester fabrics, including microfiber, satin and jersey. The fabric samples were washed up to four times and the nanoparticles released in the process were analyzed and characterized. Not an easy task, says Bernd Nowack. "Plastic, especially nanoplastics, is everywhere, including on our devices and utensils," says the scientist. "When measuring nanoplastics, we have to take this 'background noise' into account."

Large proportion of soluble particles
The researchers used an ethanol bath to distinguish nanoplastics from clumps of oligomers. Plastic pieces, no matter how small, do not dissolve in ethanol, but aggregations of oligomers do. The result: Around a third to almost 90 percent of the nanoparticles released during washing could be dissolved in ethanol. "This allowed us to show that not everything that looks like nanoplastics at first glance is in fact nanoplastics," says Nowack.

It is not yet clear whether the release of so-called nanoparticulate oligomers during the washing of textiles has negative effects on humans and the environment. "With other plastics, studies have already shown that nanoparticulate oligomers are more toxic than nanoplastics," says Nowack. "This is an indication that this should be investigated more closely." However, the researchers were able to establish that the nature of the textile and the cutting method – scissors or laser – have no major influence on the quantity of particles released.

The mechanism of release has not been clarified yet either – neither for nanoplastics nor for the oligomer particles. The good news is that the amount of particles released decreases significantly with repeated washes. It is conceivable that the oligomer particles are created during the manufacturing of the textile or split off from the fibers through chemical processes during storage. Further studies are also required in this area.

Nowack and his team are focusing on larger particles for the time being: In their next project, they want to investigate which fibers are released during washing of textiles made from renewable raw materials and whether these could be harmful to the environment and health. "Semi-synthetic textiles such as viscose or lyocell are being touted as a replacement for polyester," says Nowack. "But we don't yet know whether they are really better when it comes to releasing fibers."

Source:

Empa

Chemist Unlocks Plastic Alternatives Using Proteins and Clothing Scraps Photo: Challa Kumar, professor emeritus of chemistry, in his lab. (Contributed photo)
21.12.2023

Chemist Unlocks Plastic Alternatives Using Proteins and Clothing Scraps

Challa Kumar has developed methods to create novel plastic-like materials using proteins and fabric.

Every year, 400 million tons of plastic waste are generated worldwide. Between 19 and 23 million tons of that plastic waste makes its way into aquatic ecosystems, and the remaining goes into the ground. An additional 92 million tons of cloth waste is generated annually.

Challa Kumar, professor emeritus of chemistry, “fed up” with the tremendous amount of toxic waste people continually pump into the environment, felt compelled to do something. As a chemist, doing something meant using his expertise to develop new, sustainable materials.

“Everyone should think about replacing fossil fuel-based materials with natural materials anywhere they can to help our civilization to survive,” Kumar says. “The house is on fire, we can’t wait. If the house is on fire and you start digging a well – that is not going to work. It’s time to start pouring water on the house.”

Challa Kumar has developed methods to create novel plastic-like materials using proteins and fabric.

Every year, 400 million tons of plastic waste are generated worldwide. Between 19 and 23 million tons of that plastic waste makes its way into aquatic ecosystems, and the remaining goes into the ground. An additional 92 million tons of cloth waste is generated annually.

Challa Kumar, professor emeritus of chemistry, “fed up” with the tremendous amount of toxic waste people continually pump into the environment, felt compelled to do something. As a chemist, doing something meant using his expertise to develop new, sustainable materials.

“Everyone should think about replacing fossil fuel-based materials with natural materials anywhere they can to help our civilization to survive,” Kumar says. “The house is on fire, we can’t wait. If the house is on fire and you start digging a well – that is not going to work. It’s time to start pouring water on the house.”

Kumar has developed two technologies that use proteins and cloth, respectively, to create new materials. UConn’s Technology Commercialization Services (TCS) has filed provisional patents for both technologies.

Inspired by nature’s ability to construct a diverse array of functional materials, Kumar and his team developed a method to produce continuously tunable non-toxic materials.

“Chemistry is the only thing standing in our way,” Kumar says. “If we understand protein chemistry, we can make protein materials as strong as a diamond or as soft as a feather.”

The first innovation is a process to transform naturally occurring proteins into plastic-like materials. Kumar’s student, Ankarao Kalluri ’23 Ph.D., worked on this project.

Proteins have “reactor groups” on their surfaces which can react with substances with which they come into contact. Using his knowledge of how these groups work, Kumar and his team used a chemical link to bind protein molecules together.

This process creates a dimer – a molecule composed to two proteins. From there, the dimer is joined with another dimer to create tetramer, and so on until it becomes a large 3D molecule. This 3D aspect of the technology is unique, since most synthetic polymers are linear chains.

This novel 3D structure allows the new polymer to behave like a plastic. Just like the proteins of which it is made, the material can stretch, change shape, and fold. Thus, the material can be tailored via chemistry for a variety of specific applications.

Unlike synthetic polymers, because Kumar’s material is made of proteins and a bio-linking chemical, it can biodegrade, just like plant and animal proteins do naturally.

“Nature degrades proteins by ripping apart the amide bonds that are in them,” Kumar says. “It has enzymes to handle that sort of chemistry. We have the same amide linkages in our materials. So, the same enzymes that work in biology should also work on this material and biodegrade it naturally.”

In the lab, the team found that the material degrades within a few days in acidic solution. Now, they are investigating what happens if they bury this material in the ground, which is the fate of many post-consumer plastics.

They have demonstrated that the protein-based material can form a variety of plastic-like products, including coffee cup lids and thin transparent films. It could also be used to make fire-resistant roof tiles, or higher-end materials like, car doors, rocket cone tips, or heart valves.

The next steps for this technology are to continue testing their mechanical properties, like strength or flexibility, as well as toxicity.

“I think we need to have social consciousness that we cannot put out materials into the environment that are toxic,” Kumar says. “We just cannot. We have to stop doing that. And we cannot use materials derived from fossil fuels either.”

Kumar’s second technology uses a similar principle, but instead of just proteins, uses proteins reinforced with natural fibers, specifically cotton.

“We are creating a lot of textile waste each year due to the fast-changing fashion industry” Kumar says. “So why not use that waste to create useful materials – convert waste to wealth.”

Just like the plastic-like protein materials (called “Proteios,” derived from original Greek words), Kumar expects composite materials made from proteins and natural fibers will biodegrade without producing toxic waste.

In the lab, Kumar’s former student, doctoral candidate Adekeye Damilola, created many objects with protein-fabric composites, which include small shoes, desks, flowers, and chairs. This material contains textile fibers which serve as the linking agent with the proteins, rather than the cross-linking chemical Kumar uses for the protein-based plastics.

The crosslinking provides the novel material with the strength to withstand the weight that would be put on something like a chair or a table. The natural affinity between fibers and proteins is why it’s so hard to get food stains out of clothing. This same attraction makes strong protein-fabric materials.

While Kumar’s team has only worked with cotton so far, they expect other fiber materials, like hemp fibers or jute, would behave similarly due to their inherent but common chemical properties with cotton.

“The protein naturally adheres to the surface of the protein,” Kumar says. “We used that understanding to say ‘Hey, if it binds so tightly to cotton, why don’t we make a material out of it.’ And it works, it works amazingly.”

With the support of TCS, Professor Kumar is currently seeking industry partners to bring these technologies to market. For more information contact Michael Invernale at michael.invernale@uconn.edu.

Source:

Anna Zarra Aldrich '20 (CLAS), Office of the Vice President for Research

Photo: pixabay, Hilary Clark
01.02.2022

Cotton Fibers 2.0: Fireproof and comfortable

A new chemical process developed by Empa turns cotton into a fire-resistant fabric, that nevertheless retains the skin-friendly properties of cotton.

Conventional flame retardant cotton textiles suffer from release of formaldehyde and are uncomfortable to wear. Empa scientists managed to circumvent this problem by creating a physically and chemically independent network of flame retardants inside the fibers. This approach retains the inherently positive properties of cotton fibers, which account for three-quarters of the world's demand for natural fibers in clothing and home textiles. Cotton is skin-friendly because it can absorb considerable amounts of water and maintain a favorable microclimate on the skin.

A new chemical process developed by Empa turns cotton into a fire-resistant fabric, that nevertheless retains the skin-friendly properties of cotton.

Conventional flame retardant cotton textiles suffer from release of formaldehyde and are uncomfortable to wear. Empa scientists managed to circumvent this problem by creating a physically and chemically independent network of flame retardants inside the fibers. This approach retains the inherently positive properties of cotton fibers, which account for three-quarters of the world's demand for natural fibers in clothing and home textiles. Cotton is skin-friendly because it can absorb considerable amounts of water and maintain a favorable microclimate on the skin.

For firefighters and other emergency service personnel, protective clothing provides the most important barrier. For such purposes, cotton is mainly used as an inner textile layer that needs additional properties: For example, it must be fireproof or protect against biological contaminants. Nevertheless, it should not be hydrophobic, which would create an uncomfortable microclimate. These additional properties can be built into the cotton fibers by suitable chemical modifications.

Durability vs. toxicity
"Until now, it has always taken a compromise to make cotton fireproof," says Sabyasachi Gaan, a chemist and polymer expert who works at Empa's Advanced Fibers lab. Wash-durable flame retardant cotton in industry is produced by treating the fabric with flame retardants, which chemically links to the cellulose in the cotton. Currently, the textile industry has no other choice than to utilize formaldehyde-based chemicals – and formaldehyde is classified as a carcinogen. This has been an unsolved problem for decades. While formaldehyde-based flame retardant treatments are durable, they have additional drawbacks: The -OH groups of cellulose are chemically blocked, which considerably reduces the capability of cotton to absorb water, which results in an uncomfortable textile.

Gaan knows the chemistry of cotton fibers well and has spent many years at Empa developing flame retardants based on phosphorus chemistry that are already used in many industrial applications. Now he has succeeded in finding an elegant and easy way to anchor phosphorous in form of an independent network inside the cotton.

Independent network between cotton fibers
Gaan and his colleagues Rashid Nazir, Dambarudhar Parida and Joel Borgstädt utilized a tri-functional phosphorous compound (trivinylphosphine oxide), which has the capability of reacting only with specifically added molecules (nitrogen compounds like piperazin) to form its own network inside cotton. This makes the cotton permanently fire-resistant without blocking the favorable -OH groups. In addition, the physical phosphine oxide network also likes water. This flame retardant treatment does not include carcinogenic formaldehyde, which would endanger textile workers during textile manufacturing. The phosphine oxide networks, thus formed, does not wash out: After 50 launderings, 95 percent of the flame retardant network is still present in the fabric.

To render additional protective functionalities to the flame retardant cotton developed at Empa, the researchers also incorporated in situ generated silver nanoparticles inside the fabric. This works nicely in a one-step process together with generating the phosphine oxide networks. Silver nanoparticles provide the fiber with antimicrobial properties and survive 50 laundry cycles, too.

A high-tech solution from the pressure cooker
"We have used a simple approach to fix the phosphine oxide networks inside the cellulose," Gaan says. "For our lab experiments, we first treated the cotton with an aqueous solution of phosphorus and nitrogen compounds and then steamed it in a readily available pressure cooker to facilitate the crosslinking reaction of the phosphorus and the nitrogen molecules." The application process is compatible with equipment used in the textile industry. "Steaming textiles after dyeing, printing and finishing is a normal step in textile industry. So it doesn't require an additional investment to apply our process," states the Empa chemist.

Meanwhile, this newly developed phosphorus chemistry and its application is protected by a patent application. "Two important hurdles remain," Gaan says. "For future commercialization we need to find a suitable chemical manufacturer who can produce and supply trivinylphosphine oxide. In addition, trivinylphosphine oxide has to be REACH-registered in Europe."

Contact:
Dr. Sabyasachi Gaan
Advanced Fibers
Phone: +41 58 765 7611
sabyasachi.gaan@empa.ch
 
Contact:
Prof. Dr. Manfred Heuberger
Advanced Fibers
Phone: +41 58 765 7878
manfred.heuberger@empa.ch

A gel that releases drugs
The novel phosphorus chemistry can also be used to develop other materials, e.g. to make hydrogels that can release drugs upon changes in pH. Such gels could find application in treating wounds that heal slowly. In such wounds, the pH of the skin surface increases and the new phosphorus-based gels can be triggered to release medication or a dye that alerts doctors and nurses to the problem. Empa has also patented the production of such hydrogels.

Source:

EMPA, Rainer Klose

(c) Schoeller Textil AG
18.01.2022

A jacket from a jacket from a jacket ...

Manufacture, wear, wash, incinerate: This typical life cycle of garments, which pollutes the environment, is to be changed in the future – towards principles of circular economy with recycling at its core. Using an outdoor jacket made from PET bottles and recycled materials, Empa researchers have investigated whether the product actually delivers what the idea promises.

At first glance, it's a normal rain jacket: three layers of polyester, a lining on the inside, a water vapor-permeable membrane on top and water-repellent fabric on the outside, with a hood. But the zipper makes you wonder. Instead of ending at collar height, it pulls up over the forehead ... – who would pull it that far?

Manufacture, wear, wash, incinerate: This typical life cycle of garments, which pollutes the environment, is to be changed in the future – towards principles of circular economy with recycling at its core. Using an outdoor jacket made from PET bottles and recycled materials, Empa researchers have investigated whether the product actually delivers what the idea promises.

At first glance, it's a normal rain jacket: three layers of polyester, a lining on the inside, a water vapor-permeable membrane on top and water-repellent fabric on the outside, with a hood. But the zipper makes you wonder. Instead of ending at collar height, it pulls up over the forehead ... – who would pull it that far?

The explanation is given by Annette Mark from textile manufacturer BTK Europe, who contributed to this product. The zipper is intended to be an eye-catcher – and is primarily for recycling: Sewn tight with a thread that dissolves in boiling water, it is easier to remove than two fasteners. "Pull once and you're done," says the expert on textiles and recycling. The light green color is also due to recycling: The raw material, a granule made from a mixture of different but single-variety textiles, is dark green – and melting and spinning out the material for new yarns lightens it.

Circular economy within textile industry
Magnetic buttons, seams, hems: Every detail of the jacket follows the Design2Recycle approach, as it says on the Wear2wear website. Six companies from Europe's textile industry have joined forces in this consortium to promote circular economy. After all, more than 70 percent of all textiles produced worldwide end up in landfills or incinerators without being recycled.

How can circular economy be acheived in this industry? A team from Empa's Technology and Society lab took a closer look at the jacket and its environmental impact using life cycle analyses over a four-year period of use; including washing it three times. The candidates: a jacket produced without circular economy methods, the "starter version" of the jacket available since 2019 in blue – with an outer layer made of polyester derived from used PET bottles – and the green version from the subsequent recycling process, in which unavoidable material losses are replaced by new polyester.

The researchers' analyses show that the recycled products perform better – in eleven environmental risk categories, including global warming, toxicity to ecosystems and water scarcity. There are strikingly large advantages in air pollution, for example, because fewer pollutants are released without incineration, as well as in water scarcity, especially for the green jacket after the first recycling "loop," for which PET bottles are no longer used.

Other insights from the analyses: In terms of greenhouse effect, the maximum benefit is a good 30 percent. And the use of PET bottles does not bring any major ecological benefits. What is decisive, on the other hand, is the number of recycling cycles to produce new jackets: The balance improves from jacket to jacket – provided the quality of the polyester remains high enough.

In practice, this is challenging, as Mark explains: "Depending on the origin, the raw material sometimes differs significantly." If the fibers have been coated with certain additives, the nozzles of the spinning machines can become clogged. And in general, the quality decreases with the number of recycling cycles: more irregular structures of the yarn and lower strength.

Annette Mark's conclusion on the Empa analyses: "very realistic" and useful for improvements. "The cooperation was very good," she says, "full transparency and no compromises." The researchers also found the collaboration fruitful. "Open collaboration between science and industry is enormously important," says former team member Gregor Braun, who has since left Empa and now works as a consultant for sustainability. "Sustainability and circular economy can work well together."

Will the jacket become a market success? "The textile industry is in a state of upheaval. A rethinking is taking place right now that we shouldn't miss," says Annette Mark. But large corporations that are already developing similar products "have completely different options." After all, talks are underway with a sportswear manufacturer – for a fleece jacket, for which the Empa findings could also be useful.

Microplastic fibers from textiles
Textiles made of polyester are making the headlines because of the release microplastic fibers – for instance, during washing – which is sometimes considered a threat to humans and the environment. Empa experts have studied the formation and release of microplastic fibers. Their results: Fibers are released primarily at the fabric's edges. Their formation and release depends, among other things, on the type of fiber, surface treatment and the type of cutting. Compared to other textiles, significantly fewer fibers are released from laser-cut textiles during washing. Empa is conducting studies with industrial partners to further reduce the formation of these fibers during textile production. In Swiss wastewater treatment plants, however, microfibers are largely removed from wastewater and incinerated with the sludge.

More information:
Empa PET Recycling polyester
Source:

EMPA, Norbert Raabe

Photo: pixabay
25.05.2021

Water Saving Solution for Textile Industry EC Project Waste2Fresh

The Fraunhofer Institute for Biomedical Engineering IBMT, with its long-term expertise in nanotoxicity and nanosafety testing, contributes to a new EC project for water saving solutions for textile industry. This industry uses a vast amount of water for different steps in the textile dyeing process. It also produces a lot of wastewater, which contains a range of chemicals and dyes.

The Fraunhofer Institute for Biomedical Engineering IBMT, with its long-term expertise in nanotoxicity and nanosafety testing, contributes to a new EC project for water saving solutions for textile industry. This industry uses a vast amount of water for different steps in the textile dyeing process. It also produces a lot of wastewater, which contains a range of chemicals and dyes.

Breakthrough innovations are needed in energy intensive industries to recycle water and create closed loops in industrial processes. 20% of global industrial water pollution comes from textile manufacturing. To reduce the high amount of freshwater used in textile industry, the EC-funded Waste2Fresh project will develop a closed-loop process for textile manufacturing factories in which wastewater is collected, recycled and used again. Novel and innovative catalytic degradation approaches with highly selective separation and extraction techniques will be developed, based on nanotechnology. According to the European Commission, such “closed loops“ would significantly reduce the use of fresh water and improve water availability in the relevant EU water catchment areas, as outlined in the Water Framework Directive.

Closed loop recycling system for wastewater from textile manufacturers
Waste2Fresh meets the above challenges and industry needs by developing and demonstrating (to TRL 7) a closed loop recycling system for wastewater from textile manufacturing factories; to counteract freshwater resource scarcities and water pollution challenges exacerbated by energy intensive industries which are major users of fresh water (for e.g., processing, washing, heating, cooling).

The Waste2Fresh technology is developed to reduce current use of freshwater resources and considerably increases the recovery of water, energy and other resources (organics, salts and heavy metals). The result is a 30% increase in resource and water efficiency compared to the state-of-the-art. The system will ultimately lead to considerable environmental improvements and accordingly reduce the EC and global environmental footprint.

Fraunhofer IBMT expertise in human-toxicity and -safety testing
The Fraunhofer Institute for Biomedical Engineering IBMT will be primarily responsible for performing nanotoxicity and nanosafety testing during the whole technology process (from development to demonstration), ensuring that the developed system and processes meet relevant safety regulations. The Fraunhofer IBMT collaborates with all consortium partners developing and using to develop approaches for ensuring that the developed nanomaterial-based components meet relevant health and safety standards during their use.

For the hazard assessment of the developed nanomaterials, the Fraunhofer IBMT will perform a set of in vitro toxicity studies using commercially available human cell lines. The results of this toxicity studies will be the basis for the development of relevant safety procedures for handling and using the developed recycling technology.

 

Project funding: H2020-EU.2.1.5.3. - Sustainable, resource-efficient and low-carbon technologies in energy-intensive process industries

Duration: 12/2020- 11/2023

Coordinator:
KONYA TEKNIK UNIVERSITESI, Turkey

Project partners:
CENTRE FOR PROCESS INNOVATION LIMITED LBG, United Kingdom
ERAK GIYIM SANAYI VE TICARET ANONIM SIRKETI, Turkey
FRAUNHOFER GESELLSCHAFT ZUR FOERDERUNG DER ANGEWANDTEN FORSCHUNG E.V., Fraunhofer-Institut für Biomedizinische Technik IBMT, Germany
INNOVATION IN RESEARCH & ENGINEERING SOLUTIONS, Belgium
INSTYTUT MOLEKULYARNOI BIOLOGII I GENETYKY NAN UKRAINY, Ukraine
L'UREDERRA, FUNDACION PARA EL DESARROLLO TECNOLOGICO Y SOCIAL, Spain
NANOFIQUE LIMITED, United Kingdom
NANOGENTECH LTD, United Kingdom
PCI MEMBRANES SPOLKA Z OGRANICZONA ODPOWIEDZIALNOSCIA, Poland
STIFTELSE CSDI WATERTECH, Norway
THE OPEN UNIVERSITY, United Kingdom
ULUDAG CEVRE TEKNOLOJILERI ARGE MERKEZI SANAYI VE TICARET LIMITED SIRKETI, Turkey
UNIVERSIDAD INDUSTRIAL DE SANTANDER, Colombia
UNIVERSITA DEGLI STUDI DI TRENTO, Italy
VEREALA GMBH, Switzerland
VSI SOCIALINES INOVACIJOS SVARESNEI APLINKAI, Lithiani

Cell cultures or microorganisms can already replace many animal experiments. This is even more successful if the technologies are integrated into suitable data models. Photo: EMPA
04.08.2020

Nanosafety Research without Animal Testing

  • Risk analyses for nanoparticles

In order to reduce the number of animal experiments in research, alternative methods are being sought. This is a particular challenge if the safety of substances that have hardly been studied is to be ensured, for instance, the completely new class of nanomaterials. To accomplish just that, Empa researchers are now combining test tube experiments with mathematical modelling.

  • Risk analyses for nanoparticles

In order to reduce the number of animal experiments in research, alternative methods are being sought. This is a particular challenge if the safety of substances that have hardly been studied is to be ensured, for instance, the completely new class of nanomaterials. To accomplish just that, Empa researchers are now combining test tube experiments with mathematical modelling.

They are already in use in, say, cosmetics and the textile industry: Nanoparticles in sun blockers protect us from sunburn, and clothing with silver nanoparticles slows down bacterial growth. But the use of these tiny ingredients is also linked to the responsibility of being able to exclude negative effects for health and the environment. Nanoparticles belong to the still poorly characterized class of nanomaterials, which are between one and 100 nanometers in size and have a wide range of applications, for example in exhaust gas catalytic converters, wall paints, plastics and in nanomedicine. As new and unusual as nanomaterials are, it is still not clear whether or not they pose any risks to humans or the environment.

This is where risk analyses and life cycle assessments (LCA) come into play, which used to rely strongly on animal experiments when it came to determining the harmful effects of a new substance, including toxicity. Today, research is required to reduce and replace animal experiments wherever possible. Over the past 30 years, this approach has led to a substantial drop in animal testing, particularly in toxicological tests. The experience gained with conventional chemicals cannot simply be transferred to novel substances such as nanoparticles, however. Empa scientists are now developing new approaches, which should allow another substantial reduction in animal testing while at the same time enabling the safe use of nanomaterials.

"We are currently developing a new, integrative approach to analyze the risks of nanoparticles and to perform life cycle assessments," says Beatrice Salieri from Empa's Technology and Society lab in St. Gallen. One new feature, and one which differs from conventional analyses, is that, in addition to the mode of action of the substance under investigation, further data is included, such as the exposure and fate of a particle in the human body, so that a more holistic view is incorporated into the risk assessment.

These risk analyses are based on the nanoparticles' biochemical properties in order to develop suitable laboratory experiments, for example with cell cultures. To make sure the results from the test tube ("in vitro") also apply to the conditions in the human body ("in vivo"), the researchers use mathematical models ("in silico"), which, for instance, rely on the harmfulness of a reference substance. "If two substances, such as silver nanoparticles and silver ions, act in the very same way, the potential hazard of the nanoparticles can be calculated from that," says Salieri.

But for laboratory studies on nanoparticles to be conclusive, a suitable model system must first be developed for each type of nanoparticle. "Substances that are inhaled are examined in experiments with human lung cells," explains Empa researcher Peter Wick who is heading the "Particles-Biology Interactions" lab in St. Gallen. On the other hand, intestinal or liver cells are used to simulate digestion in the body.

This not only determines the damaging dose of a nanoparticle in cell culture experiments, but also includes all biochemical properties in the risk analysis, such as shape, size, transport patterns and the binding – if any – to other molecules. For example, free silver ions in a cell culture medium are about 100 times more toxic than silver nanoparticles bound to proteins. Such comprehensive laboratory analyses are incorporated into so-called kinetic models, which, instead of a snapshot of a situation in the test tube, can depict the complete process of particle action.

Finally, with the aid of complex algorithms, the expected biological phenomena can be calculated from these data. "Instead of 'mixing in' an animal experiment every now and then, we can determine the potential risks of nanoparticles on the basis of parallelisms with well-known substances, new data from lab analyses and mathematical models," says Empa researcher Mathias Rösslein. In future, this might also enable us to realistically represent the interactions between different nanoparticles in the human body as well as the characteristics of certain patient groups, such as elderly people or patients with several diseases, the scientist adds.

As a result of these novel risk analyses for nanoparticles, the researchers also hope to accelerate the development and market approval of new nanomaterials. They are already being applied in the "Safegraph" project, one of the projects in the EU's "Graphene Flagship" initiative, in which Empa is involved as a partner. Risk analyses and LCA for the new "wonder material" graphene are still scarce. Empa researchers have recently been able to demonstrate initial safety analyses of graphene and graphene related materials in fundamental in vitro studies. In this way, projects such as Safegraph can now better identify potential health risks and environmental consequences of graphene, while at the same time reducing the number of animal experiments.

More information:
Empa nano particles
Source:

EMPA