Electrospun zinc oxide/poly(vinyl alcohol) nanofibrous membranes: in vitro and wear trial evaluation of antimicrobial activity

The objectives of this study were to evaluate the antimicrobial properties of ZnO/poly(vinyl alcohol) (PVA) nanofibrous membranes by in vitro trials and to investigate the effectiveness and sustainability in the reduction of bacteria by conducting wear trials in real-use situations. Layered fabric systems with a very thin layer of a ZnO/PVA nanofibrous membrane layered onto polypropylene nonwoven substrates were developed and applied to shoe insoles. Eight healthy males participated in seven different wear trials in which they played a basketball game for 2 hours wearing the prototype. In the in vitro testing, ZnO/PVA nanofibrous membranes obtained from an 11 wt% PVA solution containing 3 wt% ZnO nanoparticles with a web area density of 3.0 g/m2 exhibited a 99.9% reduction of Staphylococcus aureus. In the wear trials, the shoe insoles with ZnO/PVA nanofibrous membranes obtained from the same concentration solution at a web area density of 6.0 g/m2 showed 80.9%, 84.8%, and 82.8% reductions of Staphylococcus aureus after 8, 15, and 22 days of use, respectively. In addition, another set of shoe insoles was kept at a constant temperature and humidity level after the third wear trial and resulted in 66.0% and 86.6% reductions of Staphylococcus aureus after 15 and 22 days, respectively. Although the wear trial results showed lower antimicrobial properties compared to the in vitro trials, our findings indicate that the shoe insoles showed a consistent and reasonable level of antimicrobial activity over a period of time. This suggests that ZnO/PVA nanofibrous membranes with an antimicrobial function, which are ultrathin, flexible, and highly porous, have potential for use in sports/outdoor textiles.