Safer coatings materials containing silver may be close at hand, thanks to new research by Finnish researchers.
A research team at the University of Helsinki’s Laboratory of Polymer Chemistry reports that it has successfully manufactured polymer-stabilized silver nanoparticles, which reduce exposure to silver by chemically binding the nanoparticles to polymers.
Popularity, Concern Grow
Silver nanoparticles have found wide application in coatings, paints, glues, antistatic materials, superconductors and biosensors.
Their popularity, however, has been shadowed by growing concern about their impact on human health. Laboratory studies have shown that the nanoparticles are toxic to lung, nerve, skin and other cells. They are also able to cross into the brain and travel through the blood to other body tissues. Other evidence indicates that silver ions (released by the nanoparticles) inhibit DNA replication.
Earlier this year, researchers at the University of South Carolina School of Medicine concluded that silver nanoparticles stopped growth in male reproductive cells.
Silver nanoparticles have also been shown to penetrate the skin via pores and glands, according to a technical article on the plastics portal plastemart.com. “If the skin is damaged, this facilitates the penetration of silver particles through the skin. It is therefore important that coatings containing silver nanoparticles do not release nanoparticles,” the site reports.
The Finnish researchers contend that the effect of the coating should only be based on silver ions dissolving from them. Consequently, nanoparticles should be as well bound to the coating as possible, enabling a reduction in the possible exposure to silver nanoparticles.
“Silver ions being less toxic than silver nanoparticles, a more safe material can be obtained to be used as antimicrobial coating,” the researchers write in “Synthesis of copolymer-stabilized silver nanoparticles for coating materials,” published earlier this year in the journal Colloid & Polymer Science. “This can be achieved by using thiol chemistry and covalently attach the silver nanoparticles in the coating.”
The team said its goal was “to produce a coating having antimicrobial properties of silver ions but with the silver nanoparticles firmly attached in the coating.”
The article then describes a way to produce silver nanoparticles that can be used as a component in a coating or as such to produce an antimicrobial coating.
“The silver nanoparticles presented here are stabilized by a copolymer (poly(butyl acrylate–methyl methacrylate)) that is soft and has well-known good film-producing properties. The reversible addition-fragmentation chain transfer radical polymerization technique used to prepare the polymers provides conveniently a thiol group for effective binding of the silver nanoparticles to the polymers and thus to the coating. “
According to plastemart.com, nanoparticles can be manufactured through various methods that are based on reducing metallic salts, in this case silver nitrate, in the presence of a stabilizing compound.
The Finnish research builds on the laboratory's prior work with gold nanoparticles and the expertise of the School of Science and Technology of the Aalto University and its European cooperation partners.