Physicochemical Reinforcement Unlocks Sterilization-Stable Anisotropic Hydrogels for Cell-Compatible Mock Arteries

In vitro arterial models offer ethical and robust alternatives for vascular research but require cytocompatible materials that replicate physiological mechanics. Poly(vinyl alcohol) (PVA) hydrogels produced by directional freezing and salting-out (PVA DFSO) are anisotropic yet lack stability for cell culture. Herein, methacrylated PVA (PVA-MA) hydrogels were fabricated by integrating directional freezing, salting-out, and ultraviolet (UV)-mediated covalent crosslinking to enhance mechanical performance and physicochemical stability. Two fabrication routes were examined: UV polymerization before (UVBSO) or after (UVASO) salting-out. Tensile properties and anisotropy were quantified relative to the freezing direction, and stability was assessed by swelling and mass-loss measurements. UVBSO hydrogels achieved the highest anisotropy (ratio ≈ 3.48), with Young's modulus of 50.8 kPa parallel (E||) and 14.1 kPa perpendicular (E⊥) to freezing direction but reduced stiffness (2.9-fold lower E∥ than DFSO). In contrast, UVASO constructs demonstrated robust, arterial-range performance (tensile strength ≈ 760 kPa; E∥ ≈ 378.6 kPa; ∼2.5-fold vs DFSO; ratio ≈ 3.26), reduced swelling without increasing mass loss, and sterilization compatibility. PVA-MA hydrogels could be molded into artery-like geometries and supported viable cell adhesion. This work presents a sterilizable, cytocompatible hydrogel with tunable anisotropy and arterial-mimetic mechanics, advancing the development of vascular-relevant in vitro artery models.