Ultrafine-Grained Materials With Antibacterial Properties: A Novel Approach to Reducing Spinal Implant-Associated...

Area of Science:

• Biomaterials Science
• Orthopedic Surgery
• Infectious Diseases

Background:

• Implant-associated infections are a significant risk in spinal surgery, often stemming from bacterial biofilm formation on implants.
• Current antibiotic coatings raise concerns about resistance and cytotoxicity.
• Ultrafine-grained (UFG) stainless steel offers potential antimicrobial benefits due to its nanoscale grain structure.

Purpose of the Study:

• To evaluate the antibacterial properties of UFG stainless steel against Staphylococcus aureus biofilm formation.
• To compare UFG stainless steel implants with conventional materials in both in vitro and in vivo models.

Main Methods:

• In vitro incubation of UFG and conventional SUS316L stainless steel wires with bioluminescent Staphylococcus aureus Xen36.
• Assessment of biofilm formation using crystal violet staining, colony-forming unit (CFU) counting, and quantitative PCR (qPCR).
• In vivo evaluation in mouse subcutaneous pouch and spinal implant infection models, with analysis of harvested wires.

Main Results:

• UFG wires exhibited significantly lower CFU counts compared to standard wires in vitro at multiple time points (4h, 1 day, 3 days).
• In vivo studies showed significantly reduced bacterial load on UFG wires in both the subcutaneous pouch model (Day 1) and the spinal implant model (Day 3).

Conclusions:

• UFG stainless steel implants significantly reduce early Staphylococcus aureus biofilm formation.
• The results indicate UFG materials can delay biofilm development, supporting their potential for infection-resistant spinal implants.