Hierarchically macroporous/mesoporous POC composite scaffolds with IBU-loaded hollow SiO2 microspheres for repairing infected bone defects

Abstract

Infected bone defects are normally regarded as contraindications for bone repair. In the present study, a hollow mesoporous structure of silica (SiO₂) microspheres was first synthesized and loaded with ibuprofen (IBU). Poly(1,8-octanediol-co-citrate) (POC) and β-tricalcium phosphate (β-Ca₃(PO₄)₂, β-TCP), together with IBU-loaded SiO₂ were fabricated by a 3D printing technique based on the Freeform Fabrication System with Micro-Droplet Jetting (FFS-MDJ). The physiochemical properties, compressive modulus, drug release behavior, antimicrobial properties and cell response of the composite scaffold were systematically investigated. The developed IBU-loaded SiO₂/β-TCP/POC scaffolds presented a highly interconnected porous network, macropores (350–450 μm) and mesopores (3.65 nm), as well as proper compressive modulus and biocompatibility. The addition of hollow SiO₂ microspheres was found to decrease the burst release and increase the cumulative release amount of IBU. In addition, IBU-loaded SiO₂/β-TCP/POC showed a long-term effect on inhibiting E. coli growth by agar diffusion. The result indicated that the IBU-loaded SiO₂/β-TCP/POC scaffold, with a hierarchically macro/mesoporous, highly interconnected pore structure and an effective antimicrobial property, demonstrates promise for bone regeneration in the clinical case of infected bone defects.