Antibacterial chitosan coating on nano-hydroxyapatite/polyamide66 porous bone scaffold for drug delivery

This study describes a new drug-loaded coating scaffold applied in infection therapy during bone regeneration. Chitosan (CS) containing antibacterial berberine was coated on a nano-hydroxyapatite/polyamide66 (n-HA/PA66) scaffold to realize bone regeneration together with antimicrobial properties. The porous scaffold was fabricated using the phase-inversion method with a porosity of about 84% and macropore size of 400-600 μm. The morphology, mechanical properties and drug-release behavior were investigated at different ratios of chitosan to berberine. The results show that the elastic modulus and compressive strength of the coated scaffolds were improved to 35.4 MPa and 1.7 MPa, respectively, about 7 times and 3 times higher than the uncoated scaffolds. After a burst release of berberine within the first 3 h in PBS solution, a continuous berberine release can last 150 h, which is highly dependent on the coating concentration and suitable for antibacterial requirement of orthopaedic surgery. The bactericidal test confirms a strong antibiotic effect of the delivery system and the minimum inhibitory concentration of the drug is 0.02 mg/ml. Moreover, in vitro biological evaluation demonstrates that the coating scaffolds act as a good matrix for MG63 adhesion, crawl, growth and proliferation, suggesting that the antibacterial delivery system has no cytotoxicity. We expect the drug-delivery system to have a potential application in bone regeneration or defect repair.