Introduction
Nanosilver (nanoAg) is one of the most commonly used nanomaterials because of its strong antibacterial properties. For example, nanoAg is used for medical purpose by coating or embedding for wound dressings, surgical instruments, implants and bone prostheses [1], [2] and [3]. NanoAg coatings are also used on various textiles for manufacture of clothing and socks [4] and [5]. Further, nanoAg is marketed as deodorants, room sprays, water cleaners, laundry detergents and wall paints. Therefore daily exposure to nanoAg is occurred to these consumers, in addition to workers who labor at manufacturing factory of these products.
The inhibitory effect of ionic silver, well known highly toxic to bacteria, is due to several biological events such as its adsorption to the negatively charged bacterial cell wall, generating reactive oxygen species (ROS) and de-activating cellular enzymes [6], [7],[8] and [9]. In comparison, possible mechanisms by which nanoAg inhibit bacterial growth include nanoAg attachment to cell membranes, changes of membrane permeability and intracellular ROS accumulation [10], [11] and [12].
Despite the widespread use of nanoAg products, relatively few studies have been undertaken to determine the biological effects of nanoAg exposure to mammalian cells. In this paper, we evaluated the toxicity of nanoAg and examined influences on the expression levels of several stress-response genes by nanoAg in cultured human cells.