Inside-outside Ag nanoparticles-loaded polylactic acid electrospun fiber for long-term antibacterial and bone regeneration

Bone infections caused by bacteria during bone graft implantations can impair the ability of bone tissue repair, which is currently a clinical problem. In this study, the electrospinning technique was used to prepare a polylactic acid (PLLA)/silver (Ag) composite fiber, in which the silver nanoparticles (Ag-NPs) were uniformly distributed on the inner surface of PLLA fibers; dopamine (DA) was self-polymerized on the composite fiber surface to construct the adhesive polydopamine (PDA) film and chitosan (CS) was used to regulate Ag+ in situ through pulse electrochemical deposition for the construction of a stable Ag-NPs coating (CS/Ag), achieving the steady and slow release of Ag-NPs, therefore accomplishing the construction of a inside-outside Ag-NPs-loaded PLLA/Ag@PDA@CS/Ag composite fiber with dual functions of long-lasting antibacterial effect as well as bone regeneration promotion ability. The study results showed that the composite fiber has an excellent antibacterial effect against E. coli and S. aureus, and good osteoinductive and angiogenic properties. In summary, under the dual regulations of the strong adhesion of PDA and CS chelation, the inside-outside Ag-NPs-loaded composite fiber was endowed with good physiological stability, long-term antibacterial effect and bone infection inhibition ability, making it a promising bone implant material.