Nanostructured Coatings for Spinal Fixation Screws: A Dual-Function Approach Against Biofilm Formation and Implant Failure

Abstract

Implant-associated infections represent challenging complications following orthopedic surgeries, with spinal fixation procedures being particularly linked with increased risks. Thus, urgent research is required to develop enhanced solutions to avoid bacterial colonization, associated implant failure, and severe issues. Our study is based on the laser coating of surfaces with a composite mixture of PLA/Fe3O4@CEF that can fight against infectious agents and preserve their activity for a prolonged time. In the present study, we synthesized Fe3O4@Ceftriaxone (CEF) nanoparticles by co-precipitation and blended them into polylactic acid (PLA)-based coatings that were thoroughly evaluated from physicochemical and biological points of view. The novelty of this work is the dual functionality of these coatings, combining localized, sustained antibiotic delivery with enhanced biocompatibility for spinal screw applications. The coatings exhibited substantial anti-biofilm effects, reducing Staphylococcus aureus colonization from 1.8 × 108 to 1.6 × 105 CFU/mL and Pseudomonas aeruginosa from 1.2 × 1011 to 1.9 × 106 CFU/mL after 24 h. Furthermore, in vitro assays with murine preosteoblasts and human osteoblasts demonstrated excellent biocompatibility, maintaining >95% cell viability and showing no significant cytotoxicity or inflammatory response. These results highlight the potential of PLA/Fe3O4@CEF composite coatings in preventing implant-associated infections and promoting osseointegration, offering a multifunctional strategy for improving spinal fixation screw longevity and patient outcomes.