Vine-inspired zinc-ion modified black phosphorus coating accelerates bone tissue infiltration of 3D printed scaffolds

<b>Rationale:</b> In the reconstruction of diabetic bone defects, 3D-printed scaffolds often encounter the challenge of limited and delayed tissue ingrowth in their central regions, which is critical for successful osseointegration and prognostic outcomes. Hyperglycemia induces endothelial apoptosis and impedes angiogenesis, thus inhibiting osteogenic differentiation of bone marrow stem cells (BMSCs). <b>Methods:</b> Drawing inspiration from the growth pattern of vines, we developed a Zn@BP/Si coating on the 3D-printed titanium scaffold to promote the coupling of angiogenesis and osteogenesis. This coating was achieved by Zn²⁺-modified black phosphorus (BP), which not only enhances the stability and photothermal properties of BP, but also prevents endothelial apoptosis. The effectiveness of Zn@BP/Si in the reconstruction of diabetic bone defects was investigated in rat model of diabetic femoral defect. Its effect on osteogenesis-angiogenesis coupling has also been explored in BMSCs and HUVECs. <b>Results:</b> Zn@BP/Si regulated mitochondrial dynamics and provided motivation for cell adhesion and migration, just like the climbing of vines. Notably, the regulation of enzymatic activity plays a crucial role in its inhibition of excessive mitochondrial fission. The results demonstrate that the Zn@BP/Si promotes the growth of "vascular vines" and ameliorates the angiogenic and osteogenic inhibition in diabetes. <b>Conclusions:</b> The study reveals the potential of bio-inspired Zn@BP/Si coating in angiogenesis-osteogenesis coupling and the treatment of diabetic bone defects.