Bioactivity–Structure Synergy for Osteogenesis: An Alpha-Ketoglutarate-Releasing PA66/HAp/Gelatin Gradient Porous Scaffold

Three-dimensional printed porous scaffolds provide the necessary mechanical support for bone repair. However, their inherent structural design often leads to insufficient cell attachment sites within the large pores, resulting in a low-density and uneven spatial distribution of initially adhered cells, which ultimately hampers bone regeneration. To address this limitation, we developed a gradient-functionalized scaffold by incorporating an α-ketoglutarate (AKG)-loaded gelatin (Gel/AKG) network into the macropores of a 3D-printed polyamide 66/hydroxyapatite (PH) composite scaffold. This design aims to facilitate initial cell adhesion and subsequent osteogenic differentiation. Material optimization confirmed that a formulation of 5 wt % gelatin carrying 0.25 wt % AKG achieved optimal perfusion and structural stability within the scaffold. This construct establishes an integrated microporous network that significantly enhances surface properties, actively guiding and promoting dense early cell colonization. The degradation of gelatin timely creates space for bone ingrowth, while the sustained release of AKG continuously enhances cell osteogenic activity. In vivo animal studies further revealed an 110% increase in new bone volume in the experimental group compared to the control after 8 weeks implantation. In conclusion, this strategy successfully integrates robust mechanical support, guided cell adhesion, and bioactive regulation into a spatiotemporally coordinated system, offering a promising solution for bone defect repair by harmonizing structural compatibility with functional regeneration.