Sol–gel-based zirconia biocoatings on metal structurally enhanced by polyethylene glycol

For medical components, 316L stainless steel (SS) is widely used. After a period of time, its surface naturally generates a passive oxide layer. Although this layer prevents oxidation or corrosion in an air environment, corrosion still occurs with environmental variation. Thin-film ZrO2 coatings on 316L SS deposited using a sol–gel process are a promising solution. In this work, a modified sol–gel process that uses polyethylene glycol as the binding agent was applied to improve the adhesion and reduce the thickness of ZrO2 coatings on 316L SS. The physical, chemical, and topographical properties of ZrO2 coatings were evaluated. Human umbilical vein endothelial cells were cultured on ZrO2/316L SS and stained with fluorescent dyes to observe their morphology. Then, the 3-(4, 5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium (MTS assay) was used to evaluate their proliferation activity on ZrO2/316L SS. The pro-inflammatory responses from the cells on ZrO2/316L SS were further assessed using the enzyme-linked immunosorbent assay. The results show that an appropriate annealing process is required to remove solvents and additives and to improve the mechanical properties of ZrO2 coatings. The addition of polyethylene glycol reduces the annealing temperature, enhances the mechanical properties of ZrO2 coatings, and maintains surface biocompatibility. This paper contributes to the understanding of the cells viability, ZrO2 sol–gel film cytotoxicity, and 316L SS stainless steel biocompatibility. Figure shows that the up-regulation of MCP-1 in HUVECs was time- and dose-dependent. With increasing treatment time, the released concentration of MCP-1 increased. A significant difference among doses became obvious after 4 h of treatment. Hence, the examination of pro-inflammatory responses was performed at 4 h after HUVEC incubation on the samples. The concentration of MCP-1 released by HUVECs cultured on the surface of 316L SS (the control) was higher than those on ZrO2/316L SS.