Silver nanoparticles as an antimicrobial agent: how they work

Silver nanoparticles are used as an antimicrobial agent in textiles, surfaces and other technical materials thanks to their ability to release silver ions in a controlled way. This article explains the mechanism of action described in the scientific literature, how NanoAlsa nano silver is characterised, and the type of surfaces where it is applied. For a general introduction to the material, see the guide what are copper nanoparticles?, which explains the logic shared by NanoAlsa’s certified nanometals.

Why does silver at the nanometre scale have an antimicrobial effect?

As the size of silver shrinks into the nanometre range, a far greater fraction of the atoms sits on the surface of each particle. That active surface releases silver ions (Ag+) more efficiently than silver in conventional form, which explains why very low doses of silver nanoparticles produce a measurable antimicrobial effect.

A 2024 review published in Frontiers in Microbiology describes that the antimicrobial potential of silver nanoparticles is closely associated with the release of Ag+ ions and the generation of reactive oxygen species (ROS), two mechanisms that act in a complementary way on the microorganism’s cell (Rodrigues et al., 2024).

Mechanism of action: silver ions and oxidative stress

The antimicrobial mechanism combines several simultaneous effects on the microorganism: the released Ag+ ions alter the permeability of the cell membrane, interfere with metabolism, and can bind to proteins and genetic material; in parallel, the generation of reactive oxygen species produces oxidative stress that damages cellular components.

A 2013 review on the release, transformation and behaviour of silver nanoparticles details that the rate of ion release depends on the particle’s surface coating (its ligands), and that this release amplifies the cytotoxic effect on bacteria such as E. coli (Reidy et al., 2013). This is a relevant design factor when evaluating different sources of silver nanoparticles for an antimicrobial application.

Does particle size influence the antimicrobial effect?

Particle size is one of the factors that most influences the intensity of nano silver’s antimicrobial effect. Smaller particles have a higher surface-to-volume ratio, which favours both ion release and direct interaction with biomolecules inside the microorganism’s cell.

According to reviews on the mechanism of action of silver nanoparticles, the smallest sizes — in the range of a few nanometres — show a greater capacity to interact with proteins and DNA, which translates into higher activity against bacteria at the same material concentration. This makes certified particle size a relevant technical data point when comparing different suppliers.

Certified NanoAlsa nano silver: technical characteristics

NanoAlsa nano silver has CAS number 7440-22-4, a purity of 99.9%, and a particle size under 25 nm, with 62% of the distribution between 5 and 10 nm, according to nanometry certified by the University of Chile through UICMA (Dr. Ana Luisa Riveros). This characterisation backs its use as an antimicrobial agent in the applications where it is incorporated.

All the technical documentation — nanometry certificate, chemical composition analysis and technical data sheet — is available for public download as a PDF, with no registration required, from the nano silver page.

Applications of nano silver as an antimicrobial

Silver nanoparticles are incorporated as a functional coating or additive in textiles, contact surfaces and other technical materials where the goal is to reduce the surface microbial load. The controlled ion-release mechanism allows a sustained effect throughout the service life of the treated material, without requiring frequent reapplication.

Compared with other antimicrobial metals such as copper, the choice between silver and copper depends on the specific application, the required concentration and the format used to incorporate it into the material. Both share the general mechanism of metal ion release, though with different kinetics and effective doses described in the literature for each metal.

In practice, the decision also depends on factors such as material cost, chemical compatibility with the matrix where it is incorporated (textile, polymer or coating), and whether the application also requires other properties of the base metal, such as copper’s electrical conductivity. For this reason, each case should be evaluated against the specific technical data sheet of the material before defining the final formulation.

For a buyer comparing suppliers, it is also worth checking whether the reported particle size and purity come from an in-house measurement or from an external, independently verifiable source, since that distinction affects how much weight the data should carry in a purchasing decision.

Comparison: certified nano silver vs uncertified material

Compared with uncertified silver nanomaterial, certified nano silver offers verified purity, nanometry validated by a university, and publicly downloadable documentation. The table below summarises these traceability differences.

Traceability and documentation for buyers

Every claim about NanoAlsa nano silver in this guide is backed by publicly downloadable documentation: a chemical composition analysis, a technical data sheet and a nanometry certificate from the University of Chile (UICMA). You can also review the full list of NanoAlsa certifications.

This traceability lets a buyer independently verify purity and particle size before evaluating the material for an antimicrobial application. To see available presentations and request a quote, visit the nano silver page.