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Antimicrobial silver nanoparticles – regulatory situation in the European Union


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Nanosilver is one of the most prominent nanomaterials, resulting from its capability to fight germs like bacteria, fungi and yeasts. Those germs cause nosocomial infections, food poisoning, material deterioration, food and feed spoilage. In the present review, we give insights into antimicrobial silver nanoparticles from a regulatory point of view. Silver nanoparticles release silver ions, which act as the biocidal substance. This mode of action makes it difficult for regulators to judge the risk effects related to silver nanoparticles. In this article the present situation concerning nanosilver (as a silver ion releasing technology) - state of the art, toxicological effects and risk assessment is discussed. Finally, the benefits of using silver nanoparticles in consumer products are compared to regulatory challenges in bringing such products on the market.
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Materials Today: Proceedings 4 (2017) S200S207
2214-7853 © 2017 Elsevier Ltd. This is an open access article under the CC BY-NC-ND license ( licenses/by-nc-
Selection and Peer-review under responsibility of 7th North Rhine-Westphalian Nano-Conference.
NRW 2016
Antimicrobial silver nanoparticles regulatory situation in the
European Union
Gregor Schneidera
aRAS AG, An der Irler Hoehe 3a, 93055 Regensburg, GERMANY
Nanosilver is one of the most prominent nanomaterials, resulting from its capability to fight germs like bacteria, fungi and yeasts.
Those germs cause nosocomial infections, food poisoning, material deterioration, food and feed spoilage.
In the present review, we give insights into antimicrobial silver nanoparticles from a regulatory point of view. Silver
nanoparticles release silver ions, which act as the biocidal substance. This mode of action makes it difficult for regulators to
judge the risk effects related to silver nanoparticles. In this article the present situation concerning nanosilver (as a silver ion
releasing technology) - state of the art, toxicological effects and risk assessment is discussed. Finally, the benefits of using silver
nanoparticles in consumer products are compared to regulatory challenges in bringing such products on the market.
© 2017 Elsevier Ltd. This is an open access article under the CC BY-NC-ND license ( licenses/by-
Keywords: Nanosilver, biocide, regulation, safety assessement, nanoparticle, antimicrobial
1. Introduction
Almost ten years ago, several articles published by NGOs raised concerns regarding the safety of nanomaterials.
Consequently researches and authorities all over the world requested more data on nanorisks and specific treatment
of nanomaterials in all related legislations. One of the most prominent materials is nanosilver or silver nanoparticles.
This substance is used in biocidal products for disinfection and microbial inhibition on surfaces. Biocidal products
This is an open-access article distributed under the terms of the Creative Commons Attribution-NonCommercial-ShareAlike License, which
permits non-commercial use, distribution, and reproduction in any medium, provided the original author and source are credited.
* Corresponding author. Tel.: +49 (0)941/60 717-305; fax: +49 (0)941/60 717-399.
E-mail address:
G. Schneider/ Materials Today: Proceedings 4 (2017) S200S207 S201
are necessary to control organisms that are harmful to human or animal health and to avoid damage to natural or
manufactured materials caused by microorganisms.
The use of silver was and still is multiple: Silver was used for many different applications throughout history.
Due to its properties it was used in currencies, ornaments, jewellery, electrical contacts and photography. However,
one of the most beneficial uses was the antimicrobial effect silver exerts to fungi, viruses, algae and of course
bacteria. Therefore, silver has been used as disinfectant for a long time, e.g. in treating wounds and burns. [1
For many decades nanosilver, formerly known as colloidal silver, has been used for many different purposes (e.g.
as medical product, for wound care, water treatment, disinfection, etc.) [
Innovations in surface chemistry and process engineering led to a new linne of nanosilver products in the form of
concentrates or masterbatches that are usable for active surfaces as well as materials like thermoplastic polymers.
This article explains the technology behind nanosilver and elucidates the legislative framework for bringing a
nanostructured biocide on the market. The focus here is on European biocidal products legislation, for which most
experience exists.
2. Silver use
2.1 Ancient use of nanosilver
At the end of the 19th century scientists started to produce nanosilver dispersions in a technical way. At that
time, the term “nano” was not used, yet particle suspensions were in a “millimicron” scale or colloidal dispersions.
Most of the nanosilver dispersions during this time were already used as medical products: “Under the name
“Collargol” such a kind of nanosilver has been manufactured commercially since 1897 and has been used for
medical applications.” [2]
Those medical products mainly used the antimicrobial effect of nanosilver. Infections have been treated with
colloidal silver until the 1930s. After antibiotics had been invented and became widespread, the use of nanosilver
declined for decades, but found a renewal when nanotechnology became a scientific discipline.
2.2 Mode of action
The biocidal activity of silver itself has been investigated extensively and is well described: The antimicrobial
activity of silver primarily was identified as an oligodynamic effect by Ravelin and Nägeli and described by Russel
et al. [3]. In substances showing this oligodynamic effect, only very small portions of the active substance are
needed for significant antimicrobial activity [3]. Scientists define nanosilver as particles in a size range between 1
and 100 nm [4]. It is state of the art to incorporate these nanoparticles e.g. into polymers to avoid microbial growth
on their surface [5], [6
]. The principal mode of action is described in Figure 1.
Figure 1: Schematic overview of the nanosilver effect on surfaces (© RAS AG)
S202 G. Schneider / Materials Today: Proceedings 4 (2017) S200S207
Water molecules are penetrating the upper layers of almost every surface that is based on polymers, lacquers or
resins [7
Only silver ions are released, silver nanoparticles remain in the material even when acids are used for migration
tests. This was described by Bott [
]. Nanosilver particles, incorporated in those surfaces, release silver ions (Ag+) by specific corrosion
processes [3].
Driven by concentration gradients, the silver ions are „pulled“ to the upper layer of the surface, were most of the
moisture with less silver ions is present [
] when checking silver migration out of LDPE films for food contact. For his
research, he used a LDPE film that contains silver nanoparticles. After migration in 3% acetic acid investigated a
high silver concentration and concluded, that this only could be explained by migration of silver ions. “The small
silver ions (effective ion radius Ag 0.115 nm diffuse in the polymer much faster than the SNP particles of at least 10
nm. Mechanistically this Ag migration is enhanced by the penetration of the small acetic acid molecules into the
LDPE film. This leads already in the polymer to Ag formation from the silver particles followed by acetic acid
mediated diffusion of the silver ions.” [8] His findings shew that the silver nanoparticles themselves remained in the
film and the surface. This was supported by other studies with other nanoparticles (e.g. TiN). He concluded that “not
the silver particles themselves but dissolved silver ions only are released from the polymer which is the reason for
the intended antimicrobial effect of polymers with incorporated silver nanoparticles.” [8]
]. This liquid layer contains the microbes as well, so the silver ions have
reached their target sites [ ] where they have different mechanisms to influence microbial vitality.
Silver ions exhibit a broad antimicrobial profile against bacteria, fungi and virus as well. Even bacteria strains,
which are resistant against antibiotics, e.g. MRSA can be fought with silver [10]. This makes silver and nanosilver
an excellent biocidal substance for applications in medical devices and the food sector. Examples are coated surgical
instruments, polymer implants (catheters) or nanosilver incorporated into textiles [11
3. Nanosilver as a new technology
It is obvious that almost every silver ion releasing substance is principally capable of fighting germs. The use of
nanosilver has some benefits, which are a consequence of its unique properties.
The most important reason is the enormous increase of active surface when reaching the scale of nanometers.
Nanosilver particles release magnitudes of more silver ions compared to microsilver particle of the same weight
The second advantage is the depot effect of nanosilver particles. Other technologies like silver salts release
almost all silver ions during the early stage of immersion. The elemental silver in the core of the nanosilver particle
and its outer layer of silver oxide serve as a depot which releases just small amounts of silver ions, sufficient for
high activity and an antimicrobial effect lasting for years.
]. The amount of released silver ions is directly linked to antimicrobial efficacy. This means that nanosilver
particles show a much higher biocidal activity while requiring less material compared to microsilver or full silver
Nanosilver particles continuously release silver ions. Nanosilver particles establish a steady state of silver ion
concentration that remains constant for a long time without a decrease in antimicrobial activity over time even when
the treated product is exposed to UV-light or subjected to harsh cleaning procedures. For technical applications used
in the food sector, e.g. for paints, in consumer products or hygienic surfaces for storage of food, nanosilver is
incorporated into the substrate material (e.g. polymer or coating) and is therefore irreversibly immobilized.
In polymer fibers, the nanosilver particles protect the textiles (e.g. soaker pads for fresh meat) against the
uncontrolled growth of germs. Even food related germs like Salmonella don’t have any chance to survive in these
textiles. The infection chain is interrupted and food related infectious diseases are avoided.
The major advantage of using such textiles is due to their durability, compared to other textiles, which lose
antimicrobial activity after a few washing cycles. By incorporating the nanosilver particles (no textile coating is
used) into the polymers, the particles cannot be washed out. They continuously release silver ions for a high
antimicrobial activity. Studies show, that even after 200 laundries at 60°C the textiles still remain antimicrobial [13].
The nanosilver avoids the growth of germs in the textile. This means it is not necessary to dry the textiles after
washing. Wet storage becomes feasible: Nanosilver in textiles therefore minimizes energy costs and CO2-exhaust by
making laundry more efficient. Current studies have shown that the major contribution to the energy savings during
G. Schneider/ Materials Today: Proceedings 4 (2017) S200S207 S203
a textiles lifetime is caused by washing and drying. Figure 2 shows the numbers of the improved environmental
impact: Compared to normal textiles, it is possible to save 50% of electrical energy and have 30% less
environmental impact [14
]. This is due to a lower consumption of detergents and a reduction of electric energy
consumption resulting from fewer washing and drying cycles.
Figure 2: Improved Environmental impact of nanosilver textiles: (Research Project LICARA, funded by European Union Seventh
Framework Programme (FP7/2007-2013) under grant agreement n° 315494) [14])
4. Nanospecific regulation and safety assessment
4.1. History
In the last ten years, lots of papers have been published, that talked about a wide availability and distribution of
consumer produtcs that contain nanosilver. [15 1], [ ].
Such publications and the apparently abundant availability of so-called nanoproducts in the web gave regulators
the impression that thousands of articles treated with nanosilver would already be on the market. Consequently
voices for requesting special registration procedures of nano-biocides have been raised. One of the first legislative
acts implementing nano-specific regulation was the European Biocidal product regulation (EU-BPR, [16
4.2. Biocidal product regulation (BPR) and Nanosilver
Depending on the application, the usage of a biocidal substance or product in the EU is subject to several
regulatory frameworks, for example the Biocidal Products Regulation (BPR). This regulation (528/2012 EU),
applies as of September 1st, 2013 and replaces Directive 98/8/EC.
If materials are treated with silver to avoid the growth of germs (bacteria, fungi, yeast, virus, etc.), this
application is in principle inside the scope of the BPR.
Within the authorization process substances owning similar physico-chemical, toxicological and ecotoxicological
properties can be grouped together as one “category”. As a result nanosilver is classified as active substance
S204 G. Schneider / Materials Today: Proceedings 4 (2017) S200S207
„silver“(CAS Nr. 7440-22-4). Because the bulk form of silver is a known biocide for a long time, nanosilver is
authorized according to the guidelines for “existing substances”, where transitional measures apply.
The EU-Regulation for biocides, who mentions explicitly in § 19: “Where nanomaterials are used in that product,
the risk to human health, animal health and the environment has to be assessed separately.” [16], therefore an
additional set of tests with nanosilver were necessary. Also other regulatory authorities were struggling with the
evaluation of nano-specific risks, to ensure the highest possible level of safety for their citizens.
As a result of this high demand the international “ Organisation for Economic Co-operation and Development’s
(OECD) Working Party on Manufactured Nanomaterials (WPMN) is carrying out one of the most comprehensive
nanomaterial research programs: the OECD WPMN Sponsorship Program for the Testing of Manufactured
Nanomaterials.” [17
Consequently the only nanosilver product in Europe, which can provide an additional nano-specific dataset and
nano-risk assessments, is the reference material NM 300 K. The results of this extensive research guarantee the safe
use of agpureW10 nanosilver and agpureW10 treated articles.
]. Herein the silver reference nanomaterial in the OECD WPMN international testing program,
is the nanosilver product “agpure W10” which is characterized as NM 300K. (agpure W10 is produced by RAS AG)
For food applications, the used biocidal product had to be authorized or had to be notified as existing active
substance for product type 4. Being an existing substance, the deadline for authorization respectively the inclusion
of silver (nano) into Annex I of the BPR can't be scheduled at the moment. But everybody who is using NM 300 K
can therefore benefit from the transitional measures meant before. Examples of the safety assessment, based on
public available studies elucidate the quality of existing data for nanosilver.
4.3. Technology and physical-chemical properties
EU Joint Research Centre (JRC) published a report [18] and material information sheet [18
] for NM 300 K,
which summarizes the physical and chemical properties of the material. Figure 3 shows a TEM image of this
nanosilver suspension, which demonstrates the homogenous particle size distribution.
Figure 3: TEM-image of NM 300K (= agpure W10, a product of RAS AG) nanosilver particles. (Klein et al. 2011 [17]).
4.4. Toxicology of Silver nanoparticles and Food contact migration. .
When talking about nanotoxicology it has to be considered, that the increasing number of studies on the safety of
nanomaterials was not followed by an increase in quality and reliability of such studies. Because of that Krug and
Wick [19] in their review were even forced to describe inadequate methods “together with recommendations how to
avoid this in the future, thereby contributing to a sustainable improvement of the available data.”
G. Schneider/ Materials Today: Proceedings 4 (2017) S200S207 S205
This means any results of studies on nano-risks have to be used very carefully. As a summary of data on
mammalian or ecotoxicity the use of nanosilver can be considered to be safe for humans and the environment, when
certain rules are followed. Even the use in food contact materials is feasible.
When talking about migration of silver from silver nanoparticle containing substances it could be shown, that
only the silver ion is the relevant species that is released from materials containing nanosilver: “In conclusion, not
the silver particles themselves but dissolved silver ions only are released from the polymer which is the reason for
the intended antimicrobial effect of polymers with incorporated silver nanoparticles.” [8].
Studies show, when using NM 300K incorporated in polymers this release is below the EFSA Substance
migration limit of 0.05 mg/kg of food: “The AFC panel also took note of the WHO "Guidelines for drinking-water
quality" [20]. According to these Guidelines a total lifetime oral intake of about 10 g of silver (equal to 0.39
mg/person/day) can be considered on the basis of epidemiological and pharmacokinetic knowledge as the human
NOAEL. To maintain the bacteriological quality of drinking water, levels of silver up to 0.1 mg/l, could be tolerated
without risk to health. On the basis of a daily intake of 2 l of drinking water this concentration is equal to a daily
silver intake of 0.2 mg/person and gives a total dose over 70 years of half the human NOAEL. Based on the data
above, a Restriction of 0.05 mg/kg of food (as silver) for the substance would limit intake to less than 12.5 % of the
human NOAEL” [21
The highest silver migration rates (6.8 μg/dm²) were found with 3% acetic acid as a food simulant and the plastic
film with the highest silver content (11.000 ppm). [
Even under food contact related migration conditions that can be found in normative literature like Directive
97/48/EC.: „…silver was neither found in 95% ethanol although the solubility or ability to disperse would have been
sufficient nor in isooctane which is known to be very aggressive to LDPE by swelling the polymer. From a
migration theoretical view the SNP of at least 10 nm size cannot move anymore at the applied severe test
temperatures at a measurable speed in a polymer and therefore are not expected to migrate out of the film. This is
supported by other studies with other nanoparticles (e.g. TiN).” [
The review of Cushen et al. [23
Echegoyen and Nerin [
] collected available data on silver migration from nano and non-nanosilver
containing products. The migration from the nanosilver containing product was the lowest, not exceeding 0.35
These results demonstrate that the even for food contact applications a daily use of nanosilver containing
products is safe for humans and the environment. Because these products with integrated nanosilver particles wound
not lead to a considerable silver migration into the foodstuff.
] concluded, that “in all cases the total silver migration is far below the maximum
migration limits stated by the European legislation…”.
5. Conclusion
Silver is known to be used since the 4th millennium BC. Nanosilver dispersions were used as medical products
already in the 19th century without showing adverse effects on patients. Additionally, silver has been authorized by
EU EFSA as E174 for coloring food.
The antimicrobial effect of silver is well understood. Silver ions exhibit a broad antimicrobial profile against
bacteria, fungi and virus as well. Even bacteria strains that are resistant against antibiotics, e.g. MRSA, can be
fought with silver [10]. This makes silver and nanosilver an excellent biocidal substance for applications in medical
devices and in the food sector.
Increased surface area and silver ion release combined with a silver depot effect makes nanosilver the ideal
additive to be used as a biocidal substance for any type of surfaces.
For technical applications used in the food sector, e.g. for paints, in consumer products or hygienic surfaces for
storage of food, nanosilver is incorporated into the substrate material (e.g. polymer or coating) and is therefore
irreversibly immobilized.
S206 G. Schneider / Materials Today: Proceedings 4 (2017) S200S207
Compared to normal textiles, nanosilver textiles save 50% of electrical energy and result in a 30% lower
environmental impact. This is due to a reduced consumption of detergents and a benefit of electric energy resulting
from fewer washing and drying cycles.
Silver is used in the food area to fight microorganisms that cause food spoilage or even diseases like food
poisoning. Especially animal stalls are a major source of multidrug-resistant organisms such as the dreaded MRSA
wound and pus germ or dangerous intestinal bacteria like 3,4MRGN (Multi Resistant Gram Negatives). All relevant
bacterial strains are sensitive against silver, even the multiresistant strains that will increasingly cause hygienic
The regulation of nanosilver for food contact materials is a complex issue. One topic, which is discussed at the
moment within European authorities, is the approach on how to deal with applications for BPR product type 4 to
avoid legal uncertainty and dual approval processes (EU-BPR 528/2012 vs. (EU) No 10/2011 positive list). But it
seems obvious that nanosilver products that wanted to be placed on the EU-market have to be authorized compliant
to existing law and their nano-specific risk has to be assessed additionally.
Becoming the silver reference nanomaterial within the OECD WPMN international testing program, the
nanosilver product “agpure W10” (produced by RAS AG) was characterised as NM 300K. It is the only nanosilver
in Europe which provides extensive research data on nanosafety. Summarizing the data on mammalian and
ecotoxicit, using nanosilver can be considered to be safe for humans and the environment, as long as certain rules
are followed.
The results of the nanorisk assessment and silver migration studies show that the use of a product for food contact
applications which contains NM 300K nanosilver as antimicrobial additive is safe for humans and the environment.
It will not lead to a considerable silver migration into the food.
Overall, nanosilver for food contact materials is a safe material that can be used to face new challenges in our
society. Besides the conservation of resources, more hygiene will be demanded, to guarantee safe food in a growing
population. Even new threads like multiresistant bacteria, as a consequence of factory farming, can be stopped by
using nanosilver [25
BPR Biocidal Products Regulation
CAS Chemical Abstracts Service
DNA/RNA Deoxyribonucleic acid/Ribonucleic acid
EC European Commission or European Community
EFSA European Food Safety Authority
ESBL Extended-spectrum beta-lactamase
EU European Union
FCM Food contact material
JRC Joint Research Centre
MRGN Multi Resistant Gram Negatives
MRSA Methicillin-resistant Staphylococcus aureus
NOAEL no observed adverse effect level
OECD Organisation for Economic Co-operation and Development
PIM Plastics Implementation Measure
TEM Transmission electron microscopy
UV-VIS Ultraviolet- visible
WHO World Health Organization
WPMN Working Party on Manufactured Nanomaterials
G. Schneider/ Materials Today: Proceedings 4 (2017) S200S207 S207
[1 ] Sanford, J. (2010). State of the Science Literature Review : Everything Nanosilver. Scientific, Technical, Research, Engineering and
Modeling Support Final Report.
[2] Nowack, B., Krug, H. F., & Height, M. (2011). 120 Years of Nanosilver History: Implications for Policy Makers. Environmental Science &
Technology, 11771183.
[3] Russel, a D., & Hugo, W. (1994). Antimicrobial activity and action of silver. Progress in Medicinal Chemistry, 31, 351370
[4] Percival, S. L., Bowler, P. G., & Russell, D. (2005). Bacterial resistance to silver in wound care. The Journal of Hospital Infection, 60(1), 17.
[5] Samuel, U., & Guggenbichler, J. P. (2004). Prevention of catheter-related infections: The potential of a new nano-silver impregnated catheter.
International Journal of Antimicrobial Agents, 23(SUPPL. 1), 7578.
[6] Djokic, S. and Hansen, D. (2008). Surface Treatments for Biomedical Applications. The Electrochemical Society, 11, 112.
[7] Chapman, J., Regan, F., & Sullivan, T. (2012). Nanoparticles in Anti-microbial Materials: Use and Characterisation. RSC Nanoscience and
Nanotechnology, 242.
[8] Bott, J., Störmer, A., Wolz, G., & Franz, R. (2012). Migration potential of nanoscale silver particles in food contact polyolefins.
In (Vol. 4). Berlin. Retrieved from
[9] Hahn, A., Brandes, G., Wagener, P., & Barcikowski, S. (2011). Metal ion release kinetics from nanoparticle silicone composites. Journal of
Controlled Release: Official Journal of the Controlled Release Society, 154(2), 16470.
[10] Cioffi, Nicola, and M. R. (2012). Nano-antimicrobials: progress and prospects. Springer Science & Business Media.
[11] Bechert, T., Böswald, M., Lugauer, S., Regenfus, A., Greil, J., & Guggenbichler, J. P. (1999). The Erlanger silver catheter: in vitro results
for antimicrobial activity. In Infection (Vol. 27 Suppl 1, pp. S2429).
[12]Alt, V., Bechert, T., Steinrücke, P., Wagener, M., Seidel, P., Dingeldein, E., Schnettler, R. (2004). Nanoparticulate silver. A new
antimicrobial substance for bone cement. Der Orthopäde, 33(8), 885892.
[13]GROTEN, Robert; EISENHUT, Andreas; ABDELKADER, Ameur; SCHMITT, Günter; HALLER, Judith; SCHINDLER, T. (2009).
Retrieved from
[14 Research Project LICARA, funded by European Union Seventh Framework Programme (FP7/2007-2013) under grant agreement n° 315494
[15 ] Fauss, E. (2008). The silver nanotechnology commercial inventory. University of Virginia. Retrieved from
[16] EU. (2012). Regulation (EU) No 528/2012 of the European Parliament and of the Council of 22 May 2012 concerning the making available
on the market and use of biocidal product.
[17] Klein, C., Comero, S., & Stahlmecka, B. (2011). NM-Series of repres entative manufactured nanomaterials NM-300 silver characterization,
stability, homogeneity. JRC Scientific and ….
[18] Institute for Health an Consumer Protection. (2010). Material Information Sheet NM-300K Silver. Joint Research Centre European
[19] Krug, H. F., & Wick, P. (2011). Nanotoxicology: an interdisciplinary challenge. Angewandte Chemie (International Ed. in English), 50(6),
[20]WHO (World Health Organization). (2003). Silver in Drinking-water. Guidelines for Drinking-Water Quality, 2.
[21] EFSA (2004) Opinion of the Scientific Panel on Food Additives, Flavourings, Processing Aids and Materials in Contact with Food (AFC) on
a request from the Commission related to a 4th list of substances for food contact materials. The EFSA Journal (2004)65, 1-17
[22] Hetzer, B., Greiner, R., & Meyer, C. (2013). Food Storage and Migration Studies with Nanosilver- containing Commercial and Non-
Commercial Food Packaging Materials, (55), 14.
[23] Cushen, M., Kerry, J., & Morris, M. (2013). Migration and exposure assessment of silver from a PVC nanocomposite. Food chemistry.
[24] Echegoyen, Y., & Nerín, C. (2013). Nanoparticle release from nano-silver antimicrobial food containers. Food and Chemical Toxicology, 62,
1622. doi:10.1016/j.fct.2013.08.014
[25] Rai, M. K., Deshmukh, S. D., Ingle, a. P., & Gade, a. K. (2012). Silver nanoparticles: The powerful nanoweapon against multidrug-resistant
bacteria. Journal of Applied Microbiology, 112(5), 841852.
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Here, we report the development of a new biocide based on hybrid mesoporous silica nanoparticles (MSN). The MSN was synthesized by condensation method in emulsion followed by grafting with two different silylated ionic liquid moieties, namely butyl imidazolinium bromide and imidazolinium propansulfonate betaine. Features of nanoparticles were characterized by Thermogravimetry, Infrared and ss-NMR Spectroscopy, and Transmission Electron Microscopy. The antibacterial properties were tested against a Gram-positive bacterial strain previously isolated from artefacts of interest in the field of Cultural Heritage. Interestingly, the hybrid material presents an antibacterial activity higher than its single constituents, showing a synergic effect probably due to the high local concentration of the ionic liquid anchored to nanoparticles. The more promising material was applied to fragments of stones retrieved from the Santa Margherita cave (Italy) and affected by bio-deterioration, comparing its antibacterial action with a commercial biocide.
... The hetero-aggregation between nanoparticles and biogenic particles can increase the bioavailability of nanomaterials, and these biomacromolecule-nanoparticle aggregates may offer a way of entry for nanomaterials into cells and subsequently determine the fate of the material in the organism (Lowry et al. 2012). An important consideration for several nanoparticles employed in the food, cosmetic, and medical industries (such as silver nanoparticles) is that these particles may display biocidal properties, making them less attractive to microbial colonization (Schneider 2017). This difference, combined with the polydisperse nature of plastic nanoparticles and varying surface charges, may make nanoplastics more likely to be incorporated into extracellular polymeric substances (EPSs), as the binding of biomacromolecules can coat the nanoplastic and reduce its surface energy, rendering it more stable. ...
Nanoplastics can be classified into primary and secondary nanoplastics, where primary nanoplastics are industrially produced for specific purposes and secondary nanoplastics result from plastic waste via degradation processes. The origin of nanoplastic particles is an important consideration in nanotoxicological assays. Since nanoplastics are generally thought to be produced unintentionally from microscale plastic debris, it is likely that they form aggregates with other natural and/or anthropogenic materials. Nanoplastics can take on a new biological identity in the marine environment, often dictated by the biomolecular species on their surface. Freshwater nanoplastics may display differing surface functionalities and exist in different concentrations than marine nanoplastics. Phototrophs use light as their energy source to synthesize organic compounds and are widely distributed in marine environments. Though phototrophic microorganisms are vitally important to primary production in the marine environment, heterotrophs may also associate with nanoplastics in the marine environment, and trophic transfer is thus also possible.
... The wide use of Ag NPs in many applications that involve human occupational and consumer exposure is justified by their known antibacterial, antiviral and antifungal properties to prevent infections. Despite its previous use (for instance colloidal silver 'Collargol' has been used for medical applications and has been manufactured commercially since 1897), Ag NPs gained renewed interest when its use as antibacterial and antiviral nanotechnology became more widespread and better supported by scientific evidence (Dung et al. 2020;Schneider 2017). In addition to their benefits, there are concerns about potential human and environmental hazard (Bouwmeester et al. 2009;Epstein et al. 2014;Lead et al. 2018 This is an Open Access article distributed under the terms of the Creative Commons Attribution-NonCommercial-NoDerivatives License (, which permits non-commercial re-use, distribution, and reproduction in any medium, provided the original work is properly cited, and is not altered, transformed, or built upon in any way. ...
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Children are potentially exposed to products that contain nanoparticles (NPs). In particular, silver NPs are commonly present both in products used by and around children, primarily due to their antibacterial properties. However, very few data are available regarding the ability of silver NPs to penetrate through the oral mucosa in children. In the present work, we used baby porcine buccal mucosa mounted on vertical Franz diffusion cells, as an in vitro model to investigate penetration of silver NPs (19 ± 5 nm). Permeability experiments were performed using pristine physiologically-relevant saline solution in the receiver chamber and known concentrations of NPs or ions in the donor chamber; conditions mimicked the in vivo physiological pH conditions. After physicochemical characterization of silver nanoparticles dispersed in physiological solution, we evaluated the passage of ions and NPs through the mucosa, using single particle inductively coupled plasma mass spectrometry. A flux of 4.1 ± 1.7 ng cm-2 min-1 and a lag time of 159 ± 17 min were observed through mucosa exposed to silver nanoparticles. The latter suggests nanoparticle penetration through the baby porcine mucosa and release Ag+ ions in the receptor fluid, as confirmed by computational model. Due to physiological similarity between human and pig membranes it is reasonable to assume that a trans-oral mucosa penetration could occur in children upon contact with silver nanoparticles.
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In this work, colloidal silver has been added into an acrylic clear cataphoretic bath, evaluating the effect of two different filler amounts on the durability of the composite coatings. The three series of samples were characterized by electron microscopy to assess the possible change in morphology introduced by the silver-based additive. The protective properties of the coatings were evaluated by a salt spray chamber exposure and electrochemical impedance spectroscopy measurements, evidencing the negative effect provided by high amount of silver, which introduced discontinuities in the acrylic matrix. Finally, the durability of composite coatings was studied by exposing them to UV-B radiation, observing a strong phenomenon of silver degradation. Although the coating containing high concentrations of silver demonstrated poor durability, this study revealed that small amounts of silver can be used to provide particular aesthetic features, but also to improve the protective performance of cataphoretic coatings.
The ongoing coronavirus disease 2019 (COVID‐19) pandemic and other major viral infectious diseases have become a significant threat to people’s life and economic/social development. In recent years, with the development of nanotechnology, nanomaterial‐based antiviral agents have been extensively studied. However, the clinical applications of antiviral nanomaterials are still limited. In this review, we summarize the recent advances in nanomaterial‐based antiviral strategies, mainly including antiviral nanodrugs, drug nanocarriers, and nanovaccines. The clinical challenges and prospects of nanomaterial‐based antiviral strategies are also discussed. This article is protected by copyright. All rights reserved.
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Bacterial vaginosis (BV) is the most common vaginal infection found in women in the world. Due to increasing drug‐resistance of virulent pathogen such as Gardnerella vaginalis (G. vaginalis), more than half of BV patients suffer recurrence after antibotics treatment. Here, metastable iron sulfides (mFeS) act in a Gram‐dependent manner to kill bacteria, with the ability to counteract resistant G. vaginalis for BV treatment. With screening of iron sulfide minerals, metastable Fe3S4 shows suppressive effect on bacterial growth with an order: Gram‐variable G. vaginalis >Gram‐negative bacteria>> Gram‐positive bacteria. Further studies on mechanism of action (MoA) discover that the polysulfide species released from Fe3S4 selectively permeate bacteria with thin wall and subsequently interrupt energy metabolism by inhibiting glucokinase in glycolysis, and is further synergized by simultaneously released ferrous iron that induces bactericidal damage. Such multiple MoAs enable Fe3S4 to counteract G. vaginalis strains with metronidazole‐resistance and persisters in biofilm or intracellular vacuole, without developing new drug resistance and killing probiotic bacteria. The Fe3S4 regimens successfully ameliorate BV with resistant G. vaginalis in mouse models and eliminate pathogens from patients suffering BV. Collectively, mFeS represent an antibacterial alternative with distinct MoA able to treat challenged BV and improve women health. Metastable iron sulfides (mFeS) demonstrate a Gram‐dependent antibacterial activity by releasing polysulfide species that penetrate bacteria with thin wall. The polysulfides then disrupt glycolytic energy metabolism and synergize with iron to kill bacteria without inducing new drug resistance. These mechanisms of action enable mFeS to counteract metronidazole‐resistant Gardnerella vaginalis, biofilm, and intracellular persister in bacterial vaginosis treatment.
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The emergence and spreading of the SARS-CoV-2 pandemic has forced the focus of attention on a significant issue: the realization of antimicrobial surfaces for public spaces, which do not require extensive use of disinfectants. Silver represents one of the most used elements in this context, thanks to its excellent biocidal performance. This work describes a simple method for the realization of anodized aluminum layers, whose antimicrobial features are ensured by the co-deposition with silver nitrate. The durability and the chemical resistance of the samples were evaluated by means of several accelerated degradation tests, such as the exposure in a salt spray chamber, the contact with synthetic sweat and the scrub test, highlighting the residual influence of silver in altering the protective behavior of the alumina layers. Furthermore, the ISO 22196:2011 standard was used as the reference protocol to set up an assay to measure the effective antibacterial activity of the alumina-Ag layers against both Gram-positive (Staphylococcus aureus) and Gram-negative (Escherichia coli) bacteria, even at low concentrations of silver. Finally, the Ag-containing aluminum oxide layers exhibited excellent antimicrobial performances also following the chemical–physical degradation processes, ensuring good durability over time of the antimicrobial surfaces. Overall, this work introduces a simple route for the realization of anodized aluminum surfaces with excellent antibacterial properties.
Technical Report
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The European Commission Joint Research Centre (JRC) provides scientific support to European Union policy regarding nanotechnology and public health in a sustainable environment. Over the last three years, the JRC has focused part of its work on establishing and applying a priority list (NM-Series) of representative manufactured nanomaterials (RMNs) in support of one of the most comprehensive nanomaterial research programmes that is currently being carried out: the Organisation for Economic Co-operation and Development’s (OECD) Working Party on Manufactured Nanomaterials (WPMN) Sponsorship Programme. The JRC’s provision of NM-Series RMNs to the OECD WPMN Sponsorship Programme ultimately enables the development and collection of data on characterisation, measurement, toxicological and eco-toxicological testing, and risk assessment or safety evaluation of nanomaterials. Representative nanomaterials are of utmost importance to be made available to the international scientific community to enable innovation and development of safe materials and products. This report describes the characterisation of NM-300, a RMN nano-silver dispersion containing nanoparticles (NPs) of < 20 nm, originating from a single batch of manufactured nano-silver, used for measurement and testing for hazard identification, risk and exposure assessment studies. The first series of sub-samples created from the batch is labelled NM-300, while the further processed series of NM 300 is labelled with an additional 'K' as NM 300K, in order to signify a continued processed number of sub-samples from the same batch of raw material. This NM-Series material was produced in the frame of the JRC programme on nanomaterials. It was studied by a number of international laboratories including the JRC IES analytical laboratory. Inorganic chemical characterisation of the total silver content and the homogeneity of the silver distribution were performed using photometry and ICP-OES. To this end, a dedicated method was developed and validated according to the principles of ISO 17025. Key properties of size and size distribution were studied in an inter-laboratory comparative study using SEM as well as TEM and nanoparticle tracking analysis. Furthermore, the release of silver ions from the NM-300 was studied after embedding in an acrylic matrix. The NM-300 silver <20 nm was found to contain silver particles of about 15 nm size with a narrow size distribution of 99 % of the particle number concentration exhibiting a diameter of below 20 nm. A second, much smaller abundance of particles was identified by TEM to have narrow diameter distribution of around 5 nm. The silver content and particle number of NM-300 was shown to be stable over the time of examination, lasting up to 12 months. Silver-ions were released from NM-300 silver nanomaterial, which was embedded in a poly-acrylic matrix up to a defined concentration level. The properties of NM-300 studied and described in this report demonstrate its relevance for use in measurement and testing studies, such as for hazard identification, related to the safety of nanomaterials. The studies were performed in close collaboration with the Fraunhofer Institute for Molecular and Applied Ecology (Fh-IME), German Institute of Energy and Environmental Technology e.V. (IUTA), the Swiss Federal Laboratories for Materials Science and Technology (EMPA), RAS Material Science GmbH, Germany, and the Veterinary and Agrochemical Research Centre (VAR) in Belgium.
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In the present scenario, pharmaceutical and biomedical sectors are facing the challenges of continuous increase in the multidrug-resistant (MDR) human pathogenic microbes. Re-emergence of MDR microbes is facilitated by drug and/or antibiotic resistance, which is acquired way of microbes for their survival and multiplication in uncomfortable environments. MDR bacterial infections lead to significant increase in mortality, morbidity and cost of prolonged treatments. Therefore, development, modification or searching the antimicrobial compounds having bactericidal potential against MDR bacteria is a priority area of research. Silver in the form of various compounds and bhasmas have been used in Ayurveda to treat several bacterial infections since time immemorial. As several pathogenic bacteria are developing antibiotic resistance, silver nanoparticles are the new hope to treat them. This review discusses the bactericidal potential of silver nanoparticles against the MDR bacteria. This multiactional nanoweapon can be used for the treatment and prevention of drug-resistant microbes.
The potential of nano silver particles (Ag-NPs) to migrate from food contact polyolefins into food was systematically investigated. Migration studies were carried out using low density polyethylene (LDPE) films with different concentrations of incorporated Ag-NPs in contact with different EU-official food simulants simulating long-term storage with aqueous and fatty food contact. Detectable migration of total silver as measured by inductively coupled plasma mass spectrometry (ICP-MS) was found in aqueous food simulants only. Stability tests of Ag-NPs in these food simulants by asymmetric flow field-flow fractionation (AF4) analysis showed rapid oxidative dissolution of the Ag-NPs and demonstrated that only ionic silver was present in the migration solution. Non-detectability of silver both in the isooctane and 95 % ethanol migrates indicated that Ag-NPs would not be able to migrate. These findings were supported by a new approach of migration modeling showing that nanomaterials (NMs) in general are immobilized in a polymeric matrix, resulting in a very limited hypothetical potential for the migration of NMs smaller than 3-4 nanometer in diameter. However, such small nanoparticles are usually not found in polymer nanocomposites. The results of this study suggest that migration of nanoparticles from food contact plastics cannot lead to an exposure of the consumer.
Selection of materials to be used for medical devices depends on the targeted application. For instance, in wound-healing applications, the most commonly used materials as topical dressings are various textile materials, polymeric foams, alginate, carboxy methyl cellulose (CMC) or other types of gels, and sometimes adhesives. Among textile materials, usually fabrics made of natural (e.g., cotton) or synthetic (e.g., high-density polyethylene (HDPE), nylon, polyester, etc.) fibres are used. For catheters, polymers such as polyurethane, silicone, latex or similar are applied as tubes.
The applications of surfaces treated with silver and its compounds include devices used as topical wound dressings, urinary catheters, endotracheal tubes, cardiac valves etc. Treatment of surfaces e.g. textile, polymers or metals with silver or its compounds is carried out to achieve the antimicrobial action of silver ions. Several approaches of surface treatment of medical devices for the antimicrobial purposes, such as electrodeposition, electroless deposition, physical vapor deposition, γ - radiation, etc. have been used in practice. It is clear that only silver ions are responsible for the antimicrobial activity. As confirmed experimentally, only samples containing silver compounds can deliberate silver ions in the tested media and exhibit antimicrobial activity both in vitro and in vivo. There is no evidence that elemental silver, even its so-called "nano-crystalline" state, exhibits an antimicrobial activity. Consequently, the devices coated with "nano-crystalline" silver should carefully be taken into consideration before the application.
Polymer nanocomposites incorporating metal or metal oxide nanoparticles have been developed to improve their characteristics (flexibility, gas barrier properties, antimicrobial or antioxidant properties, etc.). Among them silver nanoparticles are used because of their antimicrobial effect in many daily life materials, i.e. food packaging. However, there is not any reference to the migration of nanoparticles to the food. In this paper the results of migration studies (with different simulant solutions and times) in three commercial nanosilver plastic food containers are shown. Migration solutions were evaluated by ICP–MS and SEM–EDX analysis and silver in dissolved form and silver as nanoparticles were analyzed, a key aspect for the toxicity. Silver migration was observed for all samples studied, with the total silver migration values ranging between 1.66 and 31.46 ng/cm2 (lower than the permissible limits). Size and morphology of the silver nanoparticles changed for the different samples (ranging between 10 and 60 nm) and migration of other nanosized materials was also confirmed.
Nanotechnology is the manipulation of matter at the nanoscale, generally between 1 and 100nm. The discovery of unique nanomaterial properties has lead to novel applications in the food industry, one of which is antimicrobial food packaging materials. The objective of this study was to evaluate the migration of silver from plasticised polyvinyl chloride (PVC) nanocomposites to chicken meat following varying storage time and temperature conditions. The silver content of the chicken was quantified using inductively coupled plasma mass spectroscopy (ICPMS) and migration was found to occur within a range of 0.03-8.4mg/kg. An exposure assessment revealed that human exposure to silver (assuming a worst case scenario that all silver is in its most harmful nanoform), is likely to be below current migration limits for conventional migrants and a provisional toxicity limit; however it is acknowledged there is still considerable uncertainty about the potential harmful effects of particles at the nanoscale. A sensitivity analysis revealed that silver migration from the nanocomposite to the food surface was influenced most by the percentage fill (p<0.01), followed by storage time (p<0.01) and storage temperature (p<0.05). This study represents an initial and much needed attempt to quantify human risks from the use of nanomaterials in the food industry.