Silver nanoparticle efficacy against microorganisms
Silver nanoparticles (AgNP) have a very broad range of effectiveness. It is known that AgNPs are effective against many bacteria, fungi and viruses. Johnson and Johnson scientists performed a study against 150 microorganisms (1). Some authors even claim that silver is capable of killing ~650 disease-causing microorganisms (2).
Effective against viruses
Scientific data shows that silver nanoparticles are effective against Bovine Coronavirus and even against COVID-19 virus (3). In the latter study silver nanoparticles coated with PVP showed the best result. Another study showed that silver nanoparticles can be used against HIV virus (4). It is even possible to incorporate AgNPs within the surface coating to create an antiviral protection. For example, electrospun polyester PHBV with incorporated silver nanoparticles was proven to be efficient against feline calicivirus (5).
Efficacy against bacteria
Probably the most studied silver nanoparticle activity is against bacteria. AgNPs kill Gram-negative as well as Gram-positive bacteria. They are also effective against antibiotic resistant strains typically present in hospitals. Well known bacteria species like E. coli, S. aureus, Legionella pneumophila, Salmonella are affected by silver nanoparticles too. AgNPs attach to bacteria membranes and destabilize cell walls by changing its permeability. In addition silver induces generation of reactive oxygen that kills bacteria.
Antifungal nanosilver
Silver nanoparticles are also effective against different species of fungi. These particles stop molds and thus are important for protection of construction materials (6). They also act against plant pathogenic fungi species like Macrophomina phaseolina or Sclerotinia sclerotiorum, which makes them useful in agricultural production (7). On top of it, silver nanoparticles were tested against common fungi species causing dermatophytosis - a fungal infection of the skin (8).
Summary
Silver nanoparticles can be characterised as a broad range biocide. Their nature makes them a long lasting active material. These properties combined with known and mild toxicity effects for humans makes them an effective material for many antimicrobial applications.
References
Rennison TJ, Bayliff S, Knight J, Greenhalgh DJ. Antimicrobial efficacy of silver impregnated activated charcoal wound dressing. Poster presented at; ETRS 2003 (in vitro);
Jeong SH, Yeo SY, Yi SC. The effect of filler particle size on the antibacterial properties of compounded polymer/silver fibers. J Mater Sci, 2005. 40, 5407–5411. https://doi.org/10.1007/s10853-005-4339-8;