Surface Properties and Osteoinductivity of Silver Nanoparticle/PLGA-Coated Metal Materials

Objectives: Our previous studies have demonstrated the efficacy of silver nanoparticle (SN)-based materials in prohibiting bacterial infection. In addition, we reported the unexpected osteoinductivity of SN/PLGA-coated stainless steel alloy (SNPSA). In this study, we further elucidated the relationship of surface physicochemical properties and osteoinductivity of SN/PLGA (SNP)-coated metal materials in vitro and in vivo.
Methods: Surface physicochemical properties of SNPSA and SNP-coated titanium (SNPT) materials were analyzed by SEM, AFM, XPS, KPSM, and contact angle analyzer. Pre-osteoblastic MC3T3-E1 cells were seeded on SNPSA or SNPT plates to assess their osteoinductivity in vitro. Moreover, SNPSA and SNPT K-wires were implanted in a rat femoral intramedullary rod (FIR) model (4 mice/group). 3D micro-computed tomography scanning (μCT) analysis was utilized at 8 weeks post-implantation to evaluate bone generation in vivo.
Results: Both in vitro and in vivo assays demonstrated that SNPSA materials, but not SNPT materials, exhibit significant osteoinductivity. SEM and AFM analyses revealed no distinct morphological differences in SNPSA and SNPT materials. With increasing SN proportion, SNPSA materials were more active and hydrophilic than SNPT materials. XPS analysis demonstrated that more oxidation reactions occurred on the surface of SNPSA materials with increasing SN proportion compared with that of SNPT materials. SNs served as an anode to generate oxidized SNs on SNPSA materials, while PLGA served as a cathode to accept electrons, leading to accelerated PLGA degradation. The higher the surface atomic composition of silver a SNPSA material had, the greater oxidation reactions occurred, and the greater the osteoinductivity the SNPSA material exhibited.
Conclusions: The novel osteoinductivity of SNPSA materials should be attributed to the interactions among the nanomaterial (SN), biodegradable and bioabsorbable macromolecule (PLGA), and metal components. The unique broad-spectrum antimicrobial and osteoinductive properties of SNP-based materials reveal new possibilities of composite biomaterial development for clinical applications in dental implant.