Fast-disintegrating under-eye mask: postbiotic-loaded polyvinylpyrrolidone nanofibers for anti-aging and hydration application

Aims: The aim of this study was to develop and characterize postbiotic-loaded polyvinylpyrrolidone (PVP) nanofibers (PBNF) as a fast-disintegrating under-eye delivery system and to investigate their in vitro performance, including physicochemical properties, release kinetics, biocompatibility, and their potential to modulate skin-related cellular and molecular responses. Methods: PBNFs containing 0.5%, 1%, and 1.5% postbiotics were fabricated using pressurized gyration (PG) technology. Pure nanofibers (PNF) served as controls. The nanofibers were characterized for morphology (SEM), chemical structure (FTIR), encapsulation efficiency, dissolution behavior, release kinetics, and disintegration properties. In vitro biological performance was assessed using L929 fibroblast and HaCaT keratinocyte cells through WST-1 viability assays and morphological analysis. Additionally, gene expression analysis was performed by qPCR to evaluate the molecular effects of the formulations on extracellular matrix remodeling and inflammatory markers. Results: SEM analysis revealed uniform, bead-free nanofibers with comparable diameters across all formulations, indicating that postbiotic loading did not alter fiber morphology. FTIR spectra confirmed the successful incorporation of postbiotics into the PVP matrix. Among the formulations, 0.5% PBNF exhibited the highest encapsulation efficiency and was selected for further evaluation. Dissolution studies demonstrated a rapid initial release followed by diffusion-controlled kinetics best described by the Higuchi model. Disintegration tests showed ultrafast wetting and dissolution of the nanofibers in PBS within seconds. In vitro studies demonstrated that PBNFs promoted cell viability and proliferation in a dose- and time-dependent manner, resulting in a more balanced and controlled biological response compared to free postbiotics or PNF, without inducing cytotoxic effects. qPCR analysis demonstrated a coordinated modulation of extracellular matrix-related genes, characterized by decreased MMP1 and increased COL1A1 expression in PBNF groups, while IL6 levels remained stable. Conclusion: PBNF produced by PG represents a biocompatible, fast-disintegrating, and effective topical delivery system with strong potential for use in under-eye cosmetics and regenerative applications.