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In the past decades, iron has been one of the intensively studied biodegradable metals due to its suitable mechanical properties, but it suffers from slow degradation in a physiological environment and low bioactivity. In this work, the beneficial properties of ceramic and polymer coatings were merged to enhance the corrosion properties and biological compatibility of Fe-based biomaterials. A new bilayer coating for Fe-based biomaterials that speeds up degradation while offering controlled, localized drug release to prevent infections was prepared. In addition, bioactive coatings with an incorporated antibiotic (gentamicin, Ge) were produced to introduce antibacterial properties into the prepared biomaterials and thus increase their bioactivity. The calcium phosphate (CaP) coating layer as well as a bioactive coating layer of CaP doped with gentamicin was electrochemically deposited onto an iron substrate. A layer of poly(ethylene glycol) was subsequently applied to the selection of prepared specimens to create a bilayer ceramic/polymer coating. Electrochemical and immersion corrosion tests revealed that the application of a bilayer coating allowed achieving the desired acceleration of degradation, while the application of only a ceramic coating led to a reduction in the corrosion rate. A slight increase in the corrosion rate was observed for samples with bioactive drug-containing coatings compared to samples with drug-free coatings. Higher viability of human fibroblastic cells cultured in the extracts of the tested samples was noted for samples with a bilayer coating compared to a ceramic coating. The addition of gentamicin in the bioactive coatings had no significant effect on the viability value. Antibacterial tests proved the antibacterial activity of samples with a gentamicin-loaded coating layer against Escherichia coli and Staphylococcus aureus strains. A detailed study of the release of gentamicin from the prepared coatings revealed a different mechanism of drug release from the ceramic and the ceramic/polymer coating. Furthermore, it was found that the drug was released more slowly and uniformly from the bilayer coating. It is therefore possible to adjust the amount and duration of drug release from the bioactive coating by the thickness of the upper polymer layer. Incorporation of an antibiotic in a combined ceramic/polymer coating enabled the creation of a high-performance bioactive coating for Fe bone implants with the possibility to release a drug in the vicinity of the implant in a controlled manner to address the needs of the patient., Competing Interests: The authors declare no competing financial interest., (© 2024 The Authors. Published by American Chemical Society.)

The work is focused on the degradation, cytotoxicity, and antibacterial properties, of iron-based biomaterials with a bioactive coating layer. The foam and the compact iron samples were coated with a polyethylene glycol (PEG) polymer layer without and with gentamicin sulfate (PEG + Ge). The corrosion properties of coated and uncoated samples were studied using the degradation testing in Hanks' solution at 37 °C. The electrochemical and static immersion corrosion tests revealed that the PEG-coated samples corroded faster than samples with the bioactive PEG + Ge coating and uncoated samples. The foam samples corroded faster compared with the compact samples. To determine the cytotoxicity, cell viability was monitored in the presence of porous foam and compact iron samples. The antibacterial activity of the samples with PEG and PEG + Ge against Escherichia coli CCM 3954 and Staphylococcus aureus CCM 4223 strains was also tested. Tested PEG + Ge samples showed significant antibacterial activity against both bacterial strains. Therefore, the biodegradable iron-based materials with a bioactive coating could be a suitable successor to the metal materials studied thus far as well as the materials used in the field of medicine., Competing Interests: The authors declare no competing financial interest., (© 2024 The Authors. Published by American Chemical Society.)