Virucide activity of nanocomposites based on resin included clays for sanization of highly touched surfaces

INTRODUCTION The evergrowing problem antibiotic and disinfectant resistance disclosed by microorganisms imposes the search of new approaches for infection containment. Nanocomposites represent a promising alternative. These are solid materials made of a raw matrix including nanoparticles of the active compound with a dimension in the order of nanometers. Clays have been demonstrated to have antibacterial properties and are used in the traditional medicine. Little is known about its virucide activity. Therefore, the aim of this work is to investigate the virucide activity of nanostructured clays included in epoxide resins. MATERIALS AND METHODS The antiviral activity was tested on Herpes Simplex Virus-1 (Hsv-1), Coronavirus OC-43 (CoV-OC43) and Adenovirus-5 (AdV) with different types of clays, both natural and modified, included or not in blocks ofm epoxide resins. A biological assay (virus yield reduction) was used in order to rescue infectious particles and not only uninfectious genetic material. Briefly, the epoxide blocks were soaked in a suspension of the different viruses for1h and 24h. At the end, the viral load of rescued virus was assessed by end point titration. RESULTS Initially, the potential virucide activity of powdered clays was tested but no results were obtained because of technical problems related to clay resuspension. Interestingly, epoxide resin without nanostructured clays showed a significant antiviral efficacy at 24h esposition (> 1Log reduction) against HSV-1 and CoV-OC43 but not AdV-5. The inclusion of different types of nanostructured clays caused an increase in viral reduction only in one case, whereas with the other clays a decrease of the antiviral efficacy showed by the epoxide resin per se was observed. DISCUSSION These preliminary results show that nanocomposites containing nanostructured clays included in epoxide resin have a virucide activity. An interesting finding is the intrinsic antiviral activity of epoxide resin, suggesting that this incorporating matrix is an ideal support for clay nanocomposites. The decrease in virucide activity of some clays included in epoxide resins may be due to the interactions between resin and clay hindering the release of the active compounds.