Antibacterial and protective properties of Cr/Ag nanocomposite coatings obtained by electrochemical techniques

摘要

In the past few decades, cases involving bacteria that cannot be combated with antibiotics have become a growing problem in healthcare worldwide. Clothes and hands constitute the largest disease carriers. Studies show that multiresistant bacteria are often spread through surfaces (principally metallic and polymeric) that people frequently touch, such as door handles or light switches. For this reason, there is a great interest in the design and development of materials that provide biocidal activity.Achieving these properties on a surface is possible by means of coatings and treatments where nanotechnology plays a key role. Most of these coatings acquire their capacity by incorporating specific nanoparticles. In this sense, it has been known that silver and its compounds have strong inhibitory and biocidal activity for bacteria, fungi, and virus. Thus, compared with other metals, silver exhibits higher toxicity to microorganisms while exhibiting lower toxicity to mammalian cells.Taking into account Ag NPs properties, it would be expected that their codeposition in a metallic matrix (e.g. Ni or Cr) would lead to metallic surfaces with biocidal activity avoiding the growth of multiresistant bacteria that are often spread through surfaces that people frequently touch. However, few studies are described in the literature concerning the incorporation of Ag nanoparticles in metallic coatings.To achieve this goal, in the present work, Cr/Ag nanocomposite coatings have been deposited on brass substrates by direct current electrodeposition process from suspensions of Ag nanoparticles (Ø= 50 nm) in commercial trivalent chromium electrolytes. The effect of Ag NPs concentration, agitation and surfactant addition on the codeposition of Ag was evaluated. Moreover, the antibacterial activity and protective properties (electrochemical corrosion tests and NSS accelerated tests) of these Cr/Ag nanocomposite coatings were evaluated and compared with that of pure metal.