Photocontrolled biomimetic PEEK scaffold with black phosphorus-strontium ion cascade release for vascularized bone regeneration.

Effective repair of large bone defects poses a major clinical challenge. Traditional 3D printed polyetheretherketone (PEEK) scaffolds provide customized structures and mechanical adaptability. However, their biological inertness and lack of dynamic bioactive microenvironment limit vascular regeneration and osteogenic differentiation, ultimately limiting overall bone regeneration. This study combined photothermal responsive black phosphorus nanosheets (BPNSs) with strontium ions (Sr2+), and further modified the combination with polydopamine (PDA) to construct 'PDA@BP-Sr Nanocomposites'; subsequently a photo responsive biomimetic porous PEEK scaffold (PEEK-PDA@BP-Sr, PPBS) was developed. Under near-infrared light-induced controllable mild photothermal conditions (40-42 °C), this porous scaffold enables the time-dependent release of bioactive ions, significantly promoting the proliferation, migration, and tube formation of human umbilical vein endothelial cells (HUVECs). Moreover, it activates the ERK1/2 signaling pathway by upregulating HSP70 expression, effectively regulating the osteogenic differentiation of rat bone marrow mesenchymal stem cells (rBMSCs) in vitro. In a rabbit femoral defect model, in-vivo experiments further confirmed that NIR light irradiation enables the PPBS scaffold to dynamically regulate the vascularization bone formation coupling. This promotes early vascularization and bone regeneration, significantly accelerating bone defect repair. This study successfully developed a novel bone repair scaffold that combines structural biomimicry, mechanical adaptation, and efficient biological activity. Additionally, the study also provides important technical support for bone defect repair under conditions of insufficient blood supply.