Amino‐functionalized nano‐hydroxyapatite boosts the grafting efficiency of poly (l‐lactic acid) to enhance interfacial bonding in composite bone scaffold

Abstract Nano‐hydroxyapatite (nano‐HAP)/poly (l‐lactic acid) (PLLA) bone scaffold is expected to overcome the deficiencies and achieve the complementary advantages of individual constituents, but the weak interfacial bonding due to their thermodynamic incompatibility is detrimental to the mechanical properties. Herein, the PLLA chains were grafted onto nano‐HAP with 3‐aminopropyltriethoxysilane (KH550) as a coupling reagent to enhance the interfacial bonding with PLLA. Specifically, the silicon hydroxyl group produced by KH550 hydrolysis could form covalent bonding with the hydroxyl group of nano‐HAP, and the amino group of KH550 initiated the ring‐opening polymerization of l‐lactide monomers to graft PLLA chains onto nano‐HAP more effectively, leading to a higher grafting ratio of 16.7% compared with 7.2% in direct grafting without KH550 modification. Consequently, the tensile and compressive strength of the modified nano‐HAP/PLLA scaffold were improved by 40.8% and 59.5% enhancement due to the enhanced interfacial bonding in the composite scaffold, respectively, compared to the original nano‐HAP/PLLA scaffold. Additionally, the bone scaffold was conducive to cell adhesion and proliferation, making it an ideal candidate for bone defect repair. Highlights Amino‐functionalized nano‐HAP boosted the grafting efficiency of PLLA chains. Interfacial bonding between nano‐HAP and matrix was enhanced. Bone scaffold showed better mechanical properties and benign cytocompatibility.