A Multistage Surface Photografting Strategy To Functionalize Polylactic Acid with Osteogenic, Antioxidant, and Antibacterial Properties

The treatment of infectious bone defects requires biomaterials capable of early infection control followed by osteogenic promotion. In this study, a multistage surface photografting strategy is developed to construct multifunctional polylactic acid (PLA) for meeting this requirement. First, an osteogenic film (GAn) with adjustable alendronate density (393.5 ng/cm2 to 2922.2 ng/cm2) is fabricated on a thiol-rich PLA substrate through alternating surface photografting using methacryloyl gelatin (GelMA) and alendronate modified thiol-containing polyester. Subsequently, a multifunctional hydrogel film (Gelm) is assembled on the PLA-GAn substrate by further photografting of GelMA containing variable amounts of ε-poly-l-lysine (a broad-spectrum antibacterial agent) and tannic acid (an antioxidant agent). In vitro evaluations confirm that the Gelm film can exert antioxidant and antibacterial activity and gradually degrade in the presence of collagenase. Furthermore, the GAn film can significantly promote the proliferation, alkaline phosphatase activity, and calcium deposition of MC3T3-E1 cells. These results indicate the feasibility of this strategy to achieve PLA-based materials with potential applications in bone repair.