Preparation of electrospun silver/poly(vinyl alcohol) fibrous membranes and characterization of the effect of sterilization processes on the antibacterial activity

Silver ions (Ag+) and silver nanoparticles (AgNPs) are effective antimicrobial agents that act against a broad spectrum of bacteria. The releasing quantitation of free Ag+ is exclusively responsible for the biological toxicity, while limiting the free Ag+ in AgNPs or in polymers would largely ease the conditions. In this study, the different concentrations of silver nitrate (AgNO3) in poly(vinyl alcohol) (PVA) and an optional preheat treatment on the spinning solution before electrospinning to form the Ag+/AgNPs/PVA fibrous membranes through electrospinning technology were investigated. The morphologies, AgNPs dispersity within the PVA matrix, and the sterilizations (UV irradiation and autoclave) for Ag+/AgNPs/PVA fibrous membranes were characterized. The antibacterial activities of Ag/PVA composite membranes combined with the in-house prepared light-cured resin were also investigated. Results showed that the AgNPs/PVA fibrous membranes with antibacterial capability can be produced with the addition of at least 5 wt.% of AgNO3 to PVA. The antibacterial activities of Ag content in the PVA matrix were increased in the high presence of Ag. Noteworthy, the antibacterial enhancing effect was observed for the spinning solution groups after preheating treatment at 100°C for 1 h. The result suggests that Ag/PVA fibrous membranes sterilized by autoclave hindered antibacterial effectiveness due to the significant particle size changes in the generation of large-sized AgNPs. Nevertheless, the direct application of UV light irradiation to Ag/PVA fibrous membranes preserves their active antibacterial profile against Staphylococcus aureus and Escherichia coli. We also demonstrated that these designed AgNPs/PVA composite membranes can equip the resin with an active antibacterial capability, could benefit from the prevented bacteria breeding in microleakages and thus further reduce the possibility for secondary caries.