Bioactive Properties of Phosphate-Modified Silicon Oxycarbide Protective Coatings: Morphology and Functional Evaluation

This article presents a study on the functional properties and morphology of coatings based on amorphous silicon oxycarbide modified with phosphate ions and comodified with aluminum and boron. The objective of this modification was to enhance the biocompatibility and bioactivity without affecting its protective properties. The comodification was aimed toward stabilization of phosphate in the structure. The coatings were prepared according to the typical procedure for polymer-derived ceramics: synthesized via the sol-gel method, deposited using the dip-coating technique, and subsequently pyrolyzed. Comprehensive analyses of the morphology, surface properties, corrosion resistance, and bioactivity were conducted to assess their functional performance. The coatings exhibited uniform and smooth surfaces, with phase separation observed in the boron-modified Si<i>BP</i>OC series. Surface wettability and free energy measurements demonstrated that Si<i>P</i>OC and Si<i>BP</i>OC coatings possessed moderate hydrophilicity and favorable surface free energy for cell adhesion and bone tissue mineralization. Corrosion resistance tests in Ringer's solution revealed that Si<i>BP</i>OC coatings provided the highest protection against ion leaching, while Si<i>AlP</i>OC showed decreased resistance due to surface cracks. Bioactivity tests indicated calcium phosphate precipitation on the surface of all samples with higher hydroxyapatite formation on Si<i>P</i>OC and Si<i>AlP</i>OC coatings. In vitro tests using MG-63 osteoblast-like cells confirmed the biocompatibility of the coatings, with Si<i>P</i>OC and Si<i>BP</i>OC exhibiting the best combination of bioactivity, cell adhesion, and proliferation. These findings suggest that the phosphate- and boron-modified SiOC-based coatings are promising candidates for enhancing bone integration in orthopedic implants.