Using an Engineered Galvanic Redox System to Generate Positive Surface Potentials that Promote Osteogenic Functions

Successful osseointegration of orthopaedic and orthodontic implants is dependent on a competition between osteogenesis and bacterial contamination on the implant tissue interface. Previously, by taking advantage of the highly interactive capabilities of silver nanoparticles (AgNPs), we effectively introduced an antimicrobial effect to metal implant materials using an AgNP/poly(DL-lactic-co-glycolic acid) (PLGA) coating. Although electrical forces have been shown to promote osteogenesis, creating practical materials and devices capable of harnessing these forces to induce bone regeneration remains challenging. Here, we applied galvanic reduction oxidation (redox) principles to engineer a nanoscale galvanic redox system between AgNPs and 316L stainless steel alloy (316L-SA). Characterized by scanning electron microscopy, energy-dispersive X-ray spectroscopy, atomic force microscopy, Kelvin probe force microscopy, and contact angle measurement, the surface properties of the yield AgNP/PLGA-coated 316L-SA (SNPSA) material presented a significantly increased positive surface potential, hydrophilicity, surface fractional polarity, and surface electron accepting/donating index. Importantly, in addition to its bactericidal property, SNPSA's surface demonstrated a novel osteogenic bioactivity by promoting peri-implant bone growth. This is the first report describing the conversion of a normally deleterious galvanic redox reaction into a biologically beneficial function on a biomedical metal material. Overall, this study details an innovative strategy to design multifunctional biomaterials using a controlled galvanic redox reaction, which has broad applications in material development and clinical practice.