Atomic Layer Deposition of ZnO Coating on Biodegradable Fe‐Based Alloys

Abstract As implant‐related infections increase with a simultaneously increasing demand for implants, new material design concepts are needed to prevent such occasions from leading to failure or mortality. One approach is the antibacterial coating of implant materials with ZnO. This study applies ZnO by atomic layer deposition (ALD) on the novel class of temporary metallic implant materials. The biodegradable alloy Fe69Mn30C1 is applied as substrate. Three different coating thicknesses (33, 45, and 60 nm) deposited at the very low temperature of 100 °C are investigated regarding their mechanical behavior, roughness, wettability and in vitro degradation. With increasing thickness of the ALD coating, the roughness and corresponding contact angle slightly increased, although the surface remained hydrophilic. Initial corrosion products are analyzed by X‐ray photoelectron spectroscopy, where Zn with Phosphorous‐Oxygen compounds are identified. Furthermore, the antibacterial effect of a ZnO coating is tested against Gram‐positive Staphylococcus aureus compared to uncoated Fe69Mn30C1 and clinically applied 316L stainless steel. The ZnO coating clearly enhanced the antibacterial effect in direct material contact with S. aureus, inhibitory rate of up to 99.2% compared to uncoated 316L. As an outlook for further studies, it is demonstrated that an additively manufactured generic 3D structure can be coated using ALD.