Bioactive-coated porous anastomotic staples enhance anastomotic healing

Titanium (Ti) staples used for digestive tract reconstruction often suffer from delayed anastomotic healing and increased complication rate due to insufficient surface bioactivity. In this study, we combine a micro/nano porous Ti (Ti-OH) with an electrochemically co-deposited polydopamine (PDA) bioactive coating to construct vascular endothelial growth factor (VEGF) high loading and stage-adaptive release staples (Ti-OH-ePV). Alkali heat treatment generates hydroxyl groups and a micro/nano porous structure on the surface of Ti staples, which enhances the combination between the coating and the Ti-OH, increasing the loading capacity for VEGF. Electrochemical co-deposition embeds VEGF within the PDA network, further improving VEGF loading. Importantly, the PDA coating exhibits pH-responsive release, enabling a rapid release of VEGF under the acidic microenvironment of the inflammatory phase, thereby inducing angiogenesis and promoting macrophage polarization toward the M2 phenotype. During the subsequent proliferative phase, the sustained release of VEGF continuously drives vascular network formation, while the exposed porous structure further enhances cell migration and proliferation, synergistically promoting anastomotic healing. In a rabbit gastrointestinal anastomosis model, the Ti-OH-ePV significantly increased anastomotic bursting pressure, reduced inflammatory cytokine levels, enhanced neovascularization, and improved collagen organization, indicating markedly improved healing quality. Collectively, this study offers a theoretical basis and technical support for the development of phase-adaptive tissue repair materials.