Antimicrobial characteristics of silver are used in textiles, floor coatings and paints even though the impacts on health of silver nanoparticles are not entirely known. A research team at the University of Helsinki has successfully manufactured new polymer-stabilised silver nanoparticles, such that exposure to silver can be reduced by chemically binding the nanoparticles to polymers. The result is significant because it could impact application of silver nanoparticles in a spectrum of applications like antimicrobial textiles, containers, shower curtains, tabletops, floor coatings, paints and glues. Creams, deodorants, wound dressing products containing silver for external use is widely used. Recently, in the US, the registration of new insecticides containing silver nanoparticles has raised debate about their safety vis a vis toxicity of silver nanoparticles that can be drawn on the basis of earlier safety information on the toxicity of silver ions and metallic silver. Polymer-stabilised silver nanoparticles have been successfully manufactured at the Laboratory of Polymer Chemistry at the University. The Finnish research team has developed a solution to reducing the toxicity of silver. Nanoparticles can be manufactured through various methods that are based on reducing metallic salts, in this case silver nitrate, in the presence of a stabilising compound. The stabilising component used in the manufacturing process is a polymer with a reactive thiol end group. It is known that thiol groups bind effectively with silver, which enables the effective colloidal stabilisation of silver nanoparticles and binding to polymers. The polymer is in itself a soft, rubber-like acrylate, which contains a water-soluble block that enables silver ions to be released from the otherwise hydrophobic coating. The idea is that these silver nanoparticles could be used as a coating or its component. Many mechanisms relating to the toxicity of silver to micro-organisms have been put forward. It has been demonstrated that silver ions react in cells with the thiol groups of proteins. There is also evidence to show that silver ions damage DNA by inhibiting its replication. Silver's ability to form extremely sparingly soluble salts is also considered one of its impact mechanisms. When the chloride ions precipitate as silver chloride from the cytoplasm of cells, cell respiration is inhibited. The antibacterial efficiency of silver nanoparticles is also well-known, especially against Gram-negative bacteria such as E.coli. The silver nanoparticles work by releasing silver ions and by penetrating cells. Silver, silver ions and silver nanoparticles have generally been considered to be quite harmless to people. However, the most recent research has demonstrated that nanoparticles also penetrate mammalian cells and damage the genotype. There is even evidence to suggest that silver nanoparticles may actively find their way into cells through endocytosis. Inside the cell, hydrogen peroxide formed in cell respiration oxidises silver nanoparticles and releases silver ions from them, consequently increasing the toxicity. Thus, it can even be assumed that silver nanoparticles are cyto- or genotoxic. Moreover, it has been demonstrated that silver nanoparticles penetrate the skin via pores and glands. 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. According to Finnish researchers, 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.The work has exploited the laboratory's prior experience with gold nanoparticles and the expertise of the School of Science and Technology of the Aalto University and its European cooperation partners. Researchers at Mangalore University in India point out that silver nanoparticles are not only antibacterial against so-called gram-positive bacteria, such as resistant strains of Staphylococcus aureus and Streptococcus pneumoniae but, also against gram-negative Escherichia coli and Pseudomonas aeruginosa. The team explains how blasting silver nitrate solution with an electron beam can generate nanoparticles that are more effective at killing all kinds of bacteria, including gram-negative species that are not harmed by conventional antibacterial agents. Bacterial resistance to conventional antibiotics is threatening human health the world over. Medicinal chemists are desperately trying to develop new compounds that can kill strains such as MRSA (methicillin, or multiple-resistant Staphylococcus aureus) and E. coli O157. Frontline defenses, such as environmentally benign and cost-effective antibacterial compounds could prevent such infective agents spreading through contact with computer keyboard, phones and other devices. Researchers have been experimenting with radiation to split silver compounds, releasing silver ions that then clump together to form nanoparticles. The incentive lies in the fact that such an approach avoids the need for costly and hazardous reducing agents and can be fine-tuned to produce nanoparticles of a controlled size, which is important for controlling their properties. The team has used electron beam technology to irradiate silver nitrate solutions in a biocompatible polymer, polyvinyl alcohol, to form their silver nanoparticles. Preliminary tests show that silver nanoparticles produced by this straightforward, non-toxic method are highly active against S. aureus, E. coli, and P. aeruginosa