Polyvinyl alcohol/gelatin/carboxymethyl chitosan hydrogels with improved mechanical strength and fatigue resistance for artificial heart valves

Abstract

Hydrogels are promising materials for heart valve tissue engineering; however, their translation into medical devices remains limited by post-processing steps that can introduce defects and weaken mechanical performance. Recent advances in mechanically robust hydrogels with nanoscale fibrous architectures have renewed interest in post-processing strategies for hydrogel devices. Here, polyvinyl alcohol/gelatin/carboxymethyl chitosan hydrogels (PVA/gelatin/CMCS, denoted as PGC) were fabricated by directional freeze-casting and further reinforced by Fe3+ cross-linking and heat treatment to obtain aPGC/Fe hydrogels. The resulting aPGC/Fe hydrogels exhibited an elastic modulus of up to 8.16 MPa, toughness of 6.45 MJ m−3, and a fatigue threshold of 275.31 J m−2, close to those of native heart valve leaflets. The aPGC/Fe hydrogels showed good hemocompatibility and cytocompatibility. Furthermore, interlayer assembly was employed to mimic the native trilayer architecture of human heart valve leaflets, while microgrooves were patterned on the hydrogel surfaces to regulate near-wall fluid behavior. Artificial heart valves fabricated from the post-processed aPGC/Fe hydrogels reproduced physiologic hydrodynamic performance with effective orifice area (EOA) and regurgitant fraction (RF) values satisfying the requirements of the ISO 5840-2 standard. Collectively, these results establish a reinforcement and post-processing strategy for translating fibrous hydrogels into biomedical devices.