Compliant, Tough, Fatigue-Resistant, and Biocompatible PHEMA-Based Hydrogels as a Breast Implant Material

Breast reconstruction remains hindered by the limitations of conventional implant materials such as silicone, which exhibit hydrophobicity and poor tissue integration, often leading to complications, including capsular contracture. Here, we report the development of a poly-(HEMA-MA)/Fe³⁺ (PHM/Fe³⁺) hydrogel as a next-generation soft implant material. This hydrogel is synthesized via copolymerization of 2-hydroxyethyl methacrylate (HEMA) and maleic acid (MA), followed by immersion in FeCl₃ to induce secondary cross-linking through Fe³⁺-carboxyl coordination. The resulting homogeneous ionic network effectively mitigates stress concentration and hardening, enabling enhanced mechanical energy dissipation and conferring excellent elasticity, toughness, and fatigue resistance. In vitro and in vivo assessments demonstrate that the PHM/Fe³⁺ hydrogel is cytocompatible and elicits minimal immune response. Compared with traditional smooth and textured silicone implants, PHM/Fe³⁺ hydrogels induce significantly thinner fibrous capsule formation and promote more rapid tissue stabilization, indicating a markedly reduced risk of capsular contracture. These findings highlight the potential of PHM/Fe³⁺ hydrogels as biocompatible and mechanically resilient alternatives for breast reconstruction.