Tailoring zirconia-halloysite bioactive sponge scaffold for effective healing of infected bone defect

Abstract

Infected bone defects present a significant challenge in orthopedics, requiring biomaterials that not only promote bone regeneration but also provide effective infection control. This study presents a carboxymethyl cellulose (CMC)-based sponge scaffold fabricated with functionalized halloysite nanotubes (fHNT) and zirconia (ZrO₂) nanoparticles using a freeze-drying technique. The rationale behind this approach is to leverage the osteogenic properties of the scaffold while utilizing the antimicrobial potential of the dual drug loading system, enabling simultaneous promotion of bone regeneration and infection control. To enhance the therapeutic effectiveness, the sponge scaffold was loaded with a dual antibiotic system, comprising ampicillin (Amp) and gentamicin sulphate (GS), selected for their broad-spectrum antibacterial activity. In vitro drug release experiments demonstrated a controlled diffusion pattern, aligning with the Higuchi model. Hemocompatibility tests confirmed the sponge scaffold's biocompatibility, while in vitro assays demonstrated robust osteogenic potential, evidenced by enhanced alkaline phosphatase (ALP) activity, calcium mineralization, and collagen deposition. Additionally, the dual drug-loaded sponge scaffold exhibited significant biofilm inhibition against Escherichia coli and Staphylococcus aureus, emphasizing its efficacy in infection control. The chorioallantoic membrane assay (CAM) further revealed its angiogenic potential. This dual-functional sponge scaffold offers a promising solution for the infected bone defects by combining osteogenesis and antimicrobial activity in a single platform, addressing the limitations of current treatment and offering a clinically relevant solution to improve outcomes.