Aspirin-Loaded Anti-Inflammatory ZnO-SiO₂ Aerogel Scaffolds for Bone Regeneration

The increasing aging of the population has elevated bone defects to a significant threat to human life and health. Aerogel, a biomimetic material similar to an extracellular matrix (ECM), is considered an effective material for the treatment of bone defects. However, most aerogel scaffolds suffer from immune rejection and poor anti-inflammatory properties and are not well suited for human bone growth. In this study, we used electrospinning to prepare flexible ZnO-SiO₂ nanofibers with different zinc concentrations and further assembled them into three-dimensional composite aerogel scaffolds. The prepared scaffolds exhibited an ordered pore structure, and chitosan (CS) was utilized as a cross-linking agent with aspirin (ASA). Interestingly, the 1%ZnO-SiO₂/CS@ASA scaffolds not only exhibited good biocompatibility, bioactivity, anti-inflammation, and better mechanical properties but also significantly promoted vascularization and osteoblast differentiation in vitro. In the mouse cranial defect model, the BV/TV data showed a higher osteogenesis rate in the 1%ZnO-SiO₂/CS group (10.94 ± 0.68%) and the 1%ZnO-SiO₂/CS@ASA group (22.76 ± 1.83%), compared with the control group (5.59 ± 2.08%), and in vivo studies confirmed the ability of 1%ZnO-SiO₂/CS@ASA to promote in situ regeneration of new bone. This may be attributed to the fact that Si⁴⁺, Zn²⁺, and ASA released from 1%ZnO-SiO₂/CS@ASA scaffolds can promote angiogenesis and bone formation by stimulating the interaction between endothelial cells (ECs) and BMSCs, as well as inducing macrophage differentiation to the M2 type and downregulating the expression of pro-inflammatory factor (TNF-α) to modulate local inflammatory response. These exciting results and evidence suggest that it provides a new and effective strategy for the treatment of bone defects.