Magnetron sputtering of strontium nanolayer on zirconia implant to enhance osteogenesis

The zirconia implants have a wide range of clinical applications, however, the biological inertness and lack of osteoinductive properties limit these applications. Strontium possesses superior biocompatibility and excellent osteogenic properties. To take advantage of these, the strontium titanate-coated zirconia implants were prepared in this study by sandblasting, acid etching, and magnetron sputtering, followed by the analysis of the biological behavior. Briefly, the zirconia sheets were polished and subjected to sandblasting and acid etching. Subsequently, a nano‑strontium titanate coating was developed on the sheets by magnetron sputtering. The specimens were characterized by scanning electron microscopy (SEM), water contact angle measurement (WCA) and EDS mapping, which confirmed the physical alternation and successful deposition of the strontium titanate coating. The in vitro experiments indicated that the majority of the filopodia and actin fibers of the MC3T3-E1 cells on SA-ZrO2/Sr possessed an optimal osteogenic property to promote the osteogenic differentiation. Moreover, the RT-PCR results revealed that SA-ZrO2/Sr significantly up-regulated the gene expression of Runx2, COL-1, ALP, OPG, OPN and OCN. Further, the in vivo evaluation confirmed that the SA-ZrO2/Sr implants promoted the bone-implant osseointegration to the greatest extent as compared to SA-ZrO2 and ZrO2 implant. Overall, the SA-ZrO2/Sr system was confirmed to be a promising implant, thus, providing new pathways for an effective implant design.