People have used silver to guard against spoilage and infection for thousands of years — long before science could explain why. Today we know that much of this power comes down to silver nanoparticles: tiny fragments of metal, far smaller than the eye can see, that have a surprisingly strong effect on bacteria and other microbes. Silver nanoparticles are among the most studied and most widely used nanomaterials of all — found everywhere from sportswear that does not start to smell, through wound dressings, to filters used in water treatment. In this article we explain what silver nanoparticles actually are, how they work at the molecular level, where you will come across them, and what current research says about their safety.
Key takeaways if you're short on time
- Silver nanoparticles are minuscule particles of metallic silver roughly 1 to 100 nanometres across — about a thousand times thinner than a human hair.
- Their antimicrobial effect comes mainly from their enormous surface area. This surface releases silver ions (Ag+), which damage bacteria, and it drives the formation of reactive oxygen species that break the cell down from the inside.
- Silver acts on bacteria, fungi and a range of viruses in the laboratory. Because it attacks several targets at once, microbes find it hard to develop resistance — unlike conventional antibiotics.
- The range of uses is vast: odour-free textiles, wound dressings, coatings for medical instruments, water purification and treatment, and protective paints.
- At the concentrations you normally encounter, nanosilver is considered to have low toxicity and its use is subject to strict European regulation.
What are silver nanoparticles?
Silver nanoparticles (often simply called nanosilver) are particles of metallic silver measuring roughly 1 to 100 nanometres. One nanometre is a billionth of a metre — a distance so small that only a handful of atoms would fit side by side across it. When you break ordinary silver down to this scale, it takes on entirely new properties that you would never see in a silver ring or a set of cutlery.
Spherical particles are the most common, but silver can also be produced as rods, cubes, plates or even star shapes — and each shape behaves a little differently. The particles are rarely pure silver: their large surface oxidises, forming a thin layer of silver oxide that plays its own part in the antimicrobial action.
Why does size matter so much? The smaller the particle, the larger its surface area relative to its volume. A gram of silver divided into nanoparticles has a combined surface area many times greater than the same gram in a single lump. And the surface is where everything important happens — which is why smaller silver nanoparticles tend to be more antimicrobially active than larger ones. On top of that, silver nanoparticles have remarkable optical, electrical and thermal properties that make them useful in sensors and electronics. If you would like to understand how the nanoscale changes the behaviour of materials in general, read our article on what nanotechnology is and where nature uses it.
Silver against microbes: thousands of years of experience
Using silver against infection and spoilage is nothing new. The ancient Egyptians, Greeks and Romans stored food and liquids in silver vessels because they had noticed that the contents stayed fresh for longer. Sailors dropped silver coins into their water barrels. In the Middle Ages, wounds were dressed with silver, and American settlers crossing the prairies are said to have put silver dollars into churns of milk to stop it from turning sour.
At the turn of the twentieth century silver became a routine part of medicine — colloidal silver and silver salts were used to disinfect wounds and the eyes of newborns. It was only the arrival of antibiotics in the 1940s that pushed silver into the background for a while. Today science is returning to it, and specifically to its nano form. The reason is simple: antibiotic-resistant bacteria are a growing global problem, and silver offers a different mode of attack — one that microbes do not get used to so easily.
How do silver nanoparticles work at the molecular level?
This is the heart of the matter. The antimicrobial action of nanosilver is not a single mechanism but several processes happening at once. That is precisely where the strength of silver lies — it attacks a bacterium from several directions at the same time.
The release of silver ions (Ag+)
The surface of the nanoparticles gradually releases silver ions (Ag+), and these are the most active component. They carry a positive charge, so they bind to the negatively charged structures of the bacterial cell — above all to proteins and enzymes that contain sulphur. Once a silver ion attaches itself, the protein in question stops working. Important cellular processes are progressively shut down, the cell membrane is disrupted, and the bacterium loses the ability to survive and multiply. Here the nanoparticle acts as a kind of reservoir that releases silver ions slowly and over a long period.
The formation of reactive oxygen species (ROS)
The second main mechanism is the generation of so-called reactive oxygen species (ROS). These are highly aggressive molecules such as hydrogen peroxide and the hydroxyl radical. Silver nanoparticles promote their formation inside the bacterium, and these molecules then cause oxidative stress — literally burning and damaging membranes, proteins and the genetic information stored in DNA. The cell cannot defend itself and dies.
Mechanical disruption and an attack on DNA
Silver nanoparticles can also stick to the bacterial wall and physically puncture it, creating holes through which the contents of the cell leak out. Smaller particles can penetrate inside, where they bind to DNA and prevent it from being copied — so the bacterium cannot divide. Silver also deals with biofilms, the slimy coatings in which bacteria hide and where they are otherwise very well protected from ordinary disinfectants and from the immune system.
Because silver attacks the membrane, the enzymes, the oxidative balance and the DNA all at once, it is exceptionally difficult for microbes to develop resistance to it. That is an enormous difference from conventional antibiotics, which usually have just one target — and a single mutation can be enough for the bacterium to stop responding.
What silver acts on: bacteria, fungi and viruses
The spectrum of activity of silver nanoparticles is very broad. They act on both Gram-positive and Gram-negative bacteria, including strains resistant to antibiotics. In the laboratory they are also effective against fungal infections and moulds that are otherwise hard to treat — which matters a great deal for people with weakened immunity. Nanosilver suppresses not only pathogenic fungi and yeasts but also the moulds that appear in damp homes.
Researchers are also interested in the antiviral properties of silver. In laboratory studies, silver nanoparticles have dealt with a range of viruses — silver either disrupts the virus's outer coat or blocks the sites it uses to attach to human cells. It is important to stress, however, that most of these findings come from research under laboratory conditions and do not mean that silver should replace vaccination or medicines. This is a promising direction for research, not a finished cure.
Where are silver nanoparticles used?
Thanks to their combination of antimicrobial and physical properties, nanosilver is one of the most widespread nanomaterials in everyday and industrial use. Let us look at the most important areas.
Textiles and clothing that does not smell
The best-known use of silver is probably in textiles. The unpleasant smell of sweat is not actually caused by sweat itself — sweat is more or less odourless. The smell comes from the bacteria that break it down on the skin and in the fabric. Silver slows the growth of these bacteria, which is why functional sportswear, socks and T-shirts containing silver stay fresh for longer. And silver does not work like a perfume that simply masks the smell — it addresses the cause. You will find this sort of garment in our sportswear category. If you want to know how to choose a good pair of these socks and what to look out for, we go into detail in our article on socks that destroy odour. And for five concrete ways nanosilver is put to use in practice, see our piece on nanosilver and five ways to use it.
Medicine and wound healing
In healthcare, silver is returning to its historical roots. You will find it in wound dressings, especially for burns and slow-healing wounds, where it helps keep infection under control. Silver is also applied to the surfaces of medical instruments, catheters and implants so that bacteria do not settle on them and biofilms do not form. In research, scientists are exploring the role of nanosilver in diagnostics, biosensors and targeted tissue imaging. Some studies suggest that silver may trigger programmed cell death (apoptosis) in tumour cells, but this remains a matter of laboratory research — it is not a finished treatment, and silver is not a substitute for cancer therapy.
Water treatment and purification
Silver has also proved its worth in water treatment. Filters and membranes containing silver nanoparticles can neutralise the bacteria responsible for waterborne diseases at the point of use, without chemicals and often within minutes. This is a particularly interesting route for regions without access to safe drinking water. Silver is also added to paints, coatings, air-conditioning filters and to surfaces in facilities where hygiene comes first.
How are silver nanoparticles made?
There are essentially three ways to prepare silver nanoparticles. Chemical synthesis is the most widespread — particles are formed from a silver compound in water or a solvent using a reducing agent, and a stabiliser stops them from clumping together. The advantage is a high yield; the drawback is the formation of by-products that can burden the environment.
Physical methods (for example evaporating silver and letting it condense again) are fast and use no toxic substances, but they tend to give a lower yield. That is why a third route is becoming ever more popular — biological, or "green", synthesis. Here the particles are made using plant extracts, bacteria, fungi or small molecules such as vitamins and amino acids. It is gentle on the environment, cheap and non-toxic.
Interestingly, silver nanoparticles are not purely a creation of the laboratory. They also arise entirely naturally — certain bacteria and proteins produce them when they meet silver compounds, and they occur routinely in aquatic environments. Nature, in other words, "invented" nanosilver long before we did.
Is nanosilver safe?
There is a logical question here: if silver destroys microbes so effectively, what does it do to human cells and to the environment? The honest answer is to stick to the facts and give in neither to panic nor to exaggerated hopes.
Silver nanoparticles occur naturally, and at the concentrations you typically meet in consumer goods they are generally considered to have low toxicity. As with any substance, the dose is what counts: some laboratory studies show that at very high concentrations silver nanoparticles can also harm human cells. The products that reach customers, however, work with very small amounts of silver, are governed by European legislation and must be tested and proven safe.
The question of the environment also comes up — for instance, how much silver washes out of a functional T-shirt. Studies have shown that silver textiles release less silver during washing than you might expect, and meta-analyses suggest that the larger silver particles tend to be more problematic than those at the nanoscale. We look in detail at how nanotechnology approaches safety and regulation in general in our article on whether nanotechnologies are safe.
Disclaimer: This article is for information only and is not a substitute for medical advice. At nanoSPACE we are not doctors. We describe the antimicrobial properties of silver on the basis of scientific studies; this is not a promise of treatment or cure. If you have any health concerns, always consult a doctor.
Where to find textiles with antimicrobial nanotechnology
Silver is just one of several ways nanotechnology gives ordinary materials new abilities. At nanoSPACE we develop, for example, nanofibre textiles for allergy sufferers that form a physical barrier against dust mites and allergens — a different technology from nanosilver, but the same principle: shrink the material to the nanoscale and gain properties you will not find in an ordinary fabric. You can browse antimicrobial and odour-resistant pieces in our sportswear category below.
Nanotechnology textiles at nanoSPACE
Sportswear that stays fresh
Functional clothing and socks that fight odour at its bacterial source.
View price →Nanofibre products for allergy sufferers
Bedding and accessories that form a physical barrier against dust mites and allergens.
View price →
Conclusion: small particles with a wide reach
Silver nanoparticles are a wonderful illustration of how nanotechnology can breathe new abilities into an ordinary material. Silver, which humanity has used against infection for thousands of years, has gained a completely new strength in its nano form — thanks to the enormous surface area that releases silver ions and drives the formation of reactive oxygen species. By attacking several targets at once, it copes with bacteria, fungi and viruses in a way that microbes find hard to get used to.
From fresh sportswear, through wound dressings, to water filters — nanosilver is a quiet helper in an unexpectedly large number of places. And, used sensibly and under strict regulation, it is a material that accompanies us safely and in harmony with nature, of which, after all, it is a natural part.
Frequently asked questions
How big are silver nanoparticles?
They measure roughly 1 to 100 nanometres. One nanometre is a billionth of a metre, so silver nanoparticles are about a thousand times thinner than a human hair. It is precisely this size that gives them an enormous surface area and pronounced antimicrobial properties.
Why does silver kill bacteria?
The surface of the nanoparticles releases silver ions, which block important proteins and enzymes in the bacterium. At the same time, reactive oxygen species form and damage the membrane, the proteins and the DNA. Silver therefore attacks a bacterium from several directions at once.
Does nanosilver also work against fungi and viruses?
Yes. Silver nanoparticles have a broad spectrum of activity, and in laboratory studies they act on bacteria, yeasts, moulds and a range of viruses. Research into their antiviral properties is still ongoing, however, and silver does not replace vaccination or medicines.
Why does clothing with silver not smell?
The smell of sweat is not caused by sweat but by the bacteria that break it down. Silver slows the growth of these bacteria, so the garment stays fresh for longer. The problem is solved not with perfume but by removing the actual cause of the odour.
Is nanosilver safe for health?
At the concentrations you normally meet in consumer goods, nanosilver is considered to have low toxicity, and its use is subject to strict European regulation and testing. Silver also occurs naturally in the environment. As with any substance, the amount is what matters.
Sources
- Frontiers in Cellular and Infection Microbiology (2025) 'Silver nanoparticles as next-generation antimicrobial agents: mechanisms, challenges, and innovations against multidrug-resistant bacteria'.
- Frontiers in Microbiology (2024) 'Advances in silver nanoparticles: a comprehensive review on their potential as antimicrobial agents and their mechanisms of action elucidated by proteomics'.
- AIP Advances (2026) 'Silver nanoparticles for antibacterial applications: current insights and emerging trends', 16(3), 030702.
- Green Chemistry Letters and Reviews (2024) 'Green-synthesised silver nanoparticles: antibacterial activity and alternative mechanisms of action', 17(1).
- Nowack, B., Krug, H.F., Height, M. (2011) '120 years of nanosilver history: implications for policy makers', Environmental Science & Technology, 45(3), 1177-1183.
- Geranio, L., Heuberger, M., Nowack, B. (2009) 'The behavior of silver nanotextiles during washing', Environmental Science & Technology, 43(21), 8113-8118.