Bioactivated Lubricant-Infused Surfaces: A Dual-Action Strategy for Enhancing Osseointegration and Preventing Implant-Associated Infections

Implant-associated infections (IAIs), caused by bacterial adhesions and biofilm formations on the implant surfaces, have been the most critical threat for orthopedic surgeries. A promising strategy to prevent IAIs involves modifying the implant surface to inhibit undesirable adhesions. In particular, lubricant-infused surfaces demonstrate exceptional anti-fouling and antibacterial properties. However, their extreme anti-fouling nature also hinders the adhesion of essential biomolecules and cells, including osteogenic cells vital for bone-implant integration. Successful implantation of orthopedic implants demands strong osseointegration as well as antibacterial properties. In this study, we designed a bone morphogenetic protein 2 (BMP-2) immobilized lubricant infused surface (BILS) that promotes selective osteoblast adhesion while effectively preventing undesired biosubstance adhesions. BILS exhibits excellent repellency against various liquids (sliding angle less than 5), proteins (coverage less than 1%), and bacteria (colony-forming units 10-fold less than bare substrate). Notably, BILS enhances osteoblast adhesion, reaching 30% coverage after one day and proliferating up to 70% after three weeks. We also confirmed osteoblast differentiation on BILS through alkaline phosphatase activity and calcium assays as early and late markers, respectively. BILS-applied intramedullary nails were implanted into a rabbit femoral fracture model to investigate the antibacterial and osteogenic effects of BILS in vivo. Through histological, radiographic, and biomechanical tests, BILS was confirmed to exhibit both antibacterial as well as osseointegration properties, suggesting that BILS is a rational approach to orthopedic implants without side effects.