Silver-functionalized polyvinyl alcohol nanofiber membranes: A comparative study of nanoparticle incorporation and coating deposition

Preventing contact with pathogens is a critical requirement in filtration applications for both public and private environments. Developing antibacterial membranes is essential to enhance protection and mitigate contamination risks. In this work, a direct comparative study of two silver-based functionalization strategies applied to electrospun polyvinyl alcohol (PVA) nanofiber membranes is presented, aiming to identify the most effective approach for producing durable antibacterial filters. The first method involves in-fiber incorporation of silver nanoparticles (AgNPs) by electrospinning a colloidal AgNP dispersion blended with the PVA solution, followed by crosslinking. The second method uses physical vapor deposition (PVD) to deposit a silica- or zirconia-based composite coating embedding silver nanoclusters onto pre-crosslinked PVA fibers. Both types of membranes were characterized at each processing stage. Morphological changes were assessed by FESEM and image analysis, surface wettability by contact angle measurements, and silver content by EDS. Antibacterial activity was tested against both Gram-positive and Gram-negative bacteria, while silver ion release in water was monitored to evaluate the ability of the inorganic matrix to control Ag+ leaching. The results show that, although both strategies confer antibacterial properties, the PVD-based coating provides a more uniform silver surface distribution, controlled and sustained silver release, and preservation of nanofiber morphology, making it a promising route for the fabrication of high-performance antibacterial membranes.