Evaluation of the dermal health risk of silver nanowires as prospective medicine tool

Silver nanowires (Ag NWs) have a particularly large range of anticipated nanotechnology applications because of their intriguing optical, conductive, antimicrobial, chemical and thermal properties. They have been proposed to... [ view full abstract ]

Silver nanowires (Ag NWs) have a particularly large range of anticipated nanotechnology applications because of their intriguing optical, conductive, antimicrobial, chemical and thermal properties. They have been proposed to develop some diagnosis and monitoring tool as patches and electrodes applied on the skin or incorporated into clothes.

However, despite numerous studies of the environmental and human health impacts of silver nanoparticles, there are currently very few studies of the potential hazards of silver nanowires It is likely that some Ag NW-enabled diagnosis technologies will be in contact with human skin but to date the potential impact of such exposure has not been assessed. To address this knowledge gap, we have performed Ag NW uptake and cytotoxicity studies on human primary keratinocytes and reconstructed epidermis.

Briefly, we studied Ag NWs of two length coated with PVP. Cytotoxicity was investigated in primary keratinocytes by MTT and Neutral Red uptake assays. Penetration of Ag NW in cells was investigated by SEM and confocal microscopy. Data obtained showed cytotoxicity of Ag NW, which was lower than silver ion but not due to silver ion release in the medium. Ag NW were efficiently internalized by cells and found to be persistent. Monolayer cultures of cells do not fully represent the real (3D) architecture of skin. To overcome these limitations and to be closer to physiological conditions, we used reconstructed human epidermis that were exposed to Ag NW. Cytotoxicity was assessed by MTT assay and skin section were performed and analyzed by TEM. No cytotoxicity was observed even after 72h of exposure and penetration inside the deeper layers of the epidermis was not observed.

These data strongly suggest an efficient protection of the stratum corneum in 3D epidermis against Ag NW exposure and provide preliminary evidences on the future potential of AgNW as diagnosis and monitoring tool.