Influence of reducers on nanostructure and surface energy of silver coatings and bacterial adhesion

The high incidence of infections caused by the use of implanted biomedical devices has a severe impact on human health and health care costs. Many studies suggest a strong antimicrobial activity of silver-coated medical devices. However no studies have been reported on the effect of surface energy of silver coatings on bacterial adhesion. In this paper, 4 types of silver coatings with various surface energies were prepared on stainless steel plates using AgNO3 based electroless plating solutions with four different reducing agents, formaldehyde, hydrazine, glucose and potassium sodium tartrate tetrahydrate, respectively. The morphology and surface energy of the silver coatings were characterized with an Atomic Force Microscope and a Dataphysics OCA-20 contact angle analyzer, respectively. The anti-bacterial performance of the silver coatings was evaluated with Pseudomonas aeruginosa PA01, which frequently causes medical device-associated infections. The experimental results showed that bacterial adhesion decreased with the total surface energy of the coatings decreasing, but decreased with the electron donor component increasing. All the silver coatings performed much better than stainless steel in reducing bacterial attachment. The extended DLVO theory was used to explain bacterial adhesion behavior.