Potential-gradient reprogramming of zinc-based membranes for orthopedic applications.

Abstract

Zn-based materials degrade in vitro at rates of <0.1 mm·y^-1, which is slower than the clinical window required for barrier membranes. However, effective strategies to accelerate degradation remain limited, and increased degradation rates often result in premature perforation. Here, we introduce a 100 µm-thick Zn-based layered composite membrane that exploits chemical and potential gradients to simultaneously accelerate degradation and prevent through-thickness perforation. The membrane is sequentially stacked in ascending potential: Zn, Zn-2Cu, Zn-4Cu, and Zn-8Cu, establishing an interlayer potential gradient of 5.03 mV·µm^-1. This gradient transforms corrosion from pitting-dominated penetration to a laterally propagated mode, yielding a degradation rate of 0.17 ± 0.03 mm·y^-1 (3.4 times that of pure Zn) without perforation. The membrane exhibits an antibacterial rate exceeding 90% while reducing Cu content by 56%. Overall, the potential-gradient reprogramming enables safe accelerated degradation of biodegradable metals. STATEMENT OF SIGNIFICANCE: Current zinc-based biodegradable membranes degrade too slowly (<0.1 mm·y^-1) for clinical barrier applications, while conventional acceleration strategies inevitably cause premature perforation. This work addresses this critical limitation through a 100 µm-thick layered composite membrane with an engineered interlayer potential gradient. By redirecting corrosion from pitting-dominated penetration to lateral propagation, the membrane achieves a 3.4-fold accelerated degradation rate without through-thickness perforation-the first biodegradable metallic barrier membrane to satisfy clinical requirements. Furthermore, this strategy of establishing electrochemical gradients via compositional layering is readily extendable to other biodegradable metal systems.