Fabrication and Properties of Anisotropic PVA/HA Hydrogels for Tissue Repair

In the field of wound healing and tissue repair, hydrogel dressings have attracted significant interest as functional materials due to their excellent water retention, favorable biocompatibility, and controllable drug release capabilities. In this study, anisotropic poly(vinyl alcohol) (PVA)/hyaluronic acid (HA) hydrogels were fabricated using a directional freezing method. By adjusting the mass ratio of PVA to HA, the influence of the ordered network structures and compositions on the hydrogel properties was systematically investigated. The microstructure, hydration behavior, and mechanical properties were characterized using scanning electron microscopy (SEM), rotational rheometry, and Ultraviolet-Visible spectrophotometry. Furthermore, small-molecule Rhodamine B (RhB), macromolecular bovine serum albumin (BSA-FITC), and proanthocyanidins (PC) were selected as model drugs. Using full-immersion and Transwell-based unidirectional release systems, the effects of microstructure and composition on drug loading and release kinetics were evaluated. The results showed that when the mass ratio of PVA to HA was 3∶3, the gel network achieved a relatively balanced structural state between crosslinking density and chain segment mobility. The oriented pores formed by directional freezing further optimized the mass transfer pathway and improved drug diffusion efficiency. Furthermore, the results of CCK-8 assay indicated that none of the hydrogel extracts exhibited significant cytotoxicity to mouse fibroblast cells （L929 cells）, demonstrating good cell compatibility. Further intracellular reactive oxygen species（ROS） detection revealed that the PC-loaded anisotropic hydrogel significantly reduced H₂O₂-induced intracellular reactive oxygen species levels, effectively alleviating oxidative stress damage.