Construction Of Light-Responsive Poly (Lactic Acid)-Based Osteoinductive Composite Fibers With Antibacterial/Antioxidant Activity

The long antimicrobial time of bone repair implant materials leads to bacterial mutation and evolution,and rapid and potent sterilization to reduce tissue infection is an urgent clinical challenge.Polylactic acid(PLLA)is a clinically recognized biomedical material and occupies an important position in the field of bone regeneration,but it has deficiencies such as poor bioactivity,non-antibacterial,osteoinductive and single function,which limit its clinical application.In order to endow PLLA with excellent antibacterial and osteoinductive capabilities,it was modified as follows.(1)Zn-Ag bimetallic coating was constructed on the surface of PLLA/HANWs fibers.The zinc/silver ion with positive charge interacts with the negative charge on the bacterial surface to synergistically antibacterial;meanwhile,based on the unique photothermal properties of silver nanoparticles,the surface temperature of the material increases to 53.5°C after 10 min of 808 nm NIR laser irradiation,and the photothermal conversion efficiency reaches 35%with local temperature increase and large amount of ROS generation;combining physical signal and chemical action,the final composite material achieves Rapid and strong antibacterial effect.At the same time,the coating has excellent bioactivity,good physiological stability,excellent angiogenic properties and osteogenic properties.(2)Construction of PDA/Ag composite coating on PLLA/CeO₂ surface.Based on the unique photothermal properties of silver nanoparticles,the surface temperature of the material increased to 49°C after 10 min of 808 nm NIR laser irradiation,and the photothermal conversion efficiency reached 21%,with local temperature increase and large amount of ROS generation for rapid sterilization.In order to remove the excessive ROS generated by photothermal and avoid tissue damage,CeO₂ was doped into PLLA fibers,and CeO₂NPs in this material continuously scavenged ROS using the cyclic alternating process of Ce³⁺and Ce⁴⁺,exhibited antioxidant capacity,enhanced cell proliferation,and promoted the expression of osteogenic ALP,Col-I and OCN genes.(3)The TA/Fe/Cys composite coating was constructed on the surface of PLLA.TA and Fe³⁺formed a metal-phenolic network with strong photothermal conversion efficiency,and the surface temperature of the material increased to 55.8°C after 10 min of 808 nm NIR laser irradiation,and the photothermal conversion efficiency reached 30%,which increased the local temperature and generated a large amount of ROS to achieve rapid and strong sterilization.At the same time,the natural antioxidant tannic acid in the material can remove the excessive ROS generated during the photothermal process,showing the antioxidant ability,and the Cys in the material enhances the cell proliferation,and the material has excellent angiogenic and osteogenic properties.