Institute of Chemistry, Far Eastern Branch, Russian Academy of Sciences, Vladivostok, Russia:

A. S. Gnedenkov, Lead Researcher1, Professor of the Russian Academy of Sciences, Doctor of Сhemical Sciences, e-mail: asg17@mail.com
S. L. Sinebryukhov, Deputy Director Responsible for Research, Corresponding Member of the Russian Academy of Sciences, Doctor of Сhemical Sciences, Associate Professor, e-mail: sls@ich.dvo.ru
V. S. Filonina, Junior Researcher, e-mail: filonina.vs@gmail.com
S. V. Gnedenkov, Director, Corresponding Member of the Russian Academy of Sciences, Doctor of Сhemical Sciences, Professor, e-mail: svg21@hotmail.com

A variety of inhibitor-polymer-containing hybrid coatings were formed on the bioresorbable magnesium alloy MA8 (Mg – Mn – Ce system) in order to reduce the rate of material degradation due to a prolonged action function of active anticorrosion protection. A ceramic-like coating was produced by plasma electrolytic oxidation (PEO), which serves as a protective matrix for subsequent functionalization. The authors selected and optimized a technique providing the most efficient impregnation of the PEO layer with sodium oleate (NaOL), which at the same time helps to reduce the rate of its release from the coating due to surface treatment with a bioresorbable polymer material, i. e. polycaprolactone (PCL). The paper describes a number of hybrid coating production techniques, which are based on sequential impregnation of the base PEO layer with various concentrations of sodium oleate and PCL and on single-stage deposition of an inhibitor and a polymer from the solution. The chemical composition of the inhibitor-containing layers was determined, and the distribution of the inhibitor over the surface of the PEO coating is shown. The level of corrosion protection of the alloy was established by conducting electrochemical and volumetric tests in physiological solutions (0.9% NaCl solution, Hanks’ solution). Hybrid coatings obtained by sequential impregnation of the base PEO layer with an inhibitor and a polymer are shown to have the best corrosion resistance among the studied protective layers. Oleate-containing surface layers are characterized with a stable corrosion behaviour during 7 days of soaking in the aggressive medium. A relationship was established between the composition and properties of coa tings formed on magnesium alloys. The application of hybrid anticorrosion PEO coatings is expected to ensure the required level and duration of the corrosion protection for controlled resorption of biomedical magnesium alloy implants.

The funding for the production of biocompatible coating was provided under a Russian Science Foundation grant (Project No. 21-73-10148); the studies of the composition, corrosion rate of the material (volumetry) and its electrochemical properties were funded under a Russian Science Foundation grant (Project No. 20-13-00130).

1. Liu C., Ren Z., Xu Y., Pang S. et al. Biodegradable magnesium alloys deve loped as bone repair materials: A review. Scanning. 2018. Vol. 2018. pp. 1–15.
2. Gnedenkov A. S., Sinebryukhov S. L., Filonina V. S., Gnedenkov S. V. Hydro xyapatite-containing PEO-coating design for biodegradable Mg – 0.8 Ca alloy: Formation and corrosion behaviour. Journal of Magnesium and Alloys. 2022. DOI: 10.1016/j.jma.2022.12.002
3. Kiselevskiy M. V., Anisimova N. Yu., Polotskiy B. E., Martynenko N. S. et al. Biodegradable magnesium alloys as promising medical materials (Review). Modern Technologies in Medicine. 2019. Vol. 11, No. 3. pp. 146–157.
4. Volkov D. A., Leonov A. A., Mukhina I. Yu., Uridiya Z. P. Potential application of biodegradable magnesium alloys (Review). Trudy VIAM. 2019. No. 3. pp. 35–43.
5. Khlusov I. A., Mitrichenko D. V., Prosolov A. B., Nikolaeva O. O. et al. A brief overview of biomedical properties and applications of magnesium alloys for bone tissue bioengineering. Bulletin of Siberian Medicine. 2019. Vol. 18, No. 2. pp. 274–286.
6. Frolova T. S., Boykov A. A., Tarkova A. R., Orishchenko K. E. et al. Understanding the cytotoxic effect of magnesium alloys on cell cultures. Circulation Pathology and Cardiac Surgery. 2019. Vol. 23, No. 3. pp. 22–29.
7. Drobyshev A., Gurganchova Z., Redko N., Komissarov A., Bazhenov V. et al. An in vivo rat study of bioresorbable Mg–2Zn–2Ga alloy implants. Bioengineering. 2023. Vol. 10, No. 2. p. 273.
8. Yang Y., He C., Dianyu E., Yang W. et al. Mg bone implant: Features, developments and perspectives. Materials & Design. 2020. Vol. 185. 108259.
9. Rahman M., Li Y., Wen C. HA coating on Mg alloys for biomedical applications: A review. Journal of Magnesium and Alloys. 2020. Vol. 8, No. 3. pp. 929–943.
10. Amiri H., Mohammadi I., Afshar A. Electrophoretic deposition of nanozirconia coating on AZ91D magnesium alloy for bio-corrosion control purposes. Surface and Coatings Technology. 2017. Vol. 311. pp. 182–190.
11. Mohedano M., Luthringer B. J. C., Mingo B., Feyerabend F. et al. Bioactive plasma electrolytic oxidation coatings on Mg – Ca alloy to control degradation behaviour. Surface and Coatings Technology. 2017. Vol. 315. pp. 454–467.
12. Gnedenkov A. S., Sinebryukhov S. L., Mashtalyar D. V., Imshinetskiy I. M. et al. Effect of microstructure on the corrosion resistance of TIG welded 1579 alloy. Materials. 2019. Vol. 12, No. 16. DOI: 10.3390/ma12162615
13. Gnedenkov A. S., Sinebryukhov S. L., Filonina V. S., Ustinov A. Y. et al. New polycaprolactone-containing self-healing coating design for enhance corrosion resistance of the magnesium and its alloys. Polymers. 2023. Vol. 15, No. 1. 202.
14. Zhang F., Ju P., Pan M., Zhang D. et al. Self-healing mechanisms in smart protective coatings: A review. Corrosion Science. 2018. Vol. 144. pp. 74–88.
15. Wang Y., Zuo Y., Tang Y. Inhibition effect and mechanism of sodium oleate on passivation and pitting corrosion of steel in simulated concrete pore solution. Construction and Building Materials. 2018. Vol. 167. pp. 197–204.
16. Luo H., Guan Y. C., Han K. N. Inhibition of mild steel corrosion by sodium dodecyl benzene sulfonate and sodium oleate in acidic solutions. Corrosion. 1998. Vol. 54, No. 8. pp. 619–627.
17. Chirkunov A. A., Rakoch A. G., Monakhova E. V., Gladkova A. A. et al. Corrosion protection of magnesium alloy by PEO-coatings containing sodium oleate. International Journal of Corrosion and Scale Inhibition. 2019. Vol. 8, No. 4. pp. 1170–1188.
18. Kameshima Y., Sasaki H., Isobe T., Nakajima A., Okada K. Synthesis of composites of sodium oleate/Mg – Al-ascorbic acid-layered double hydroxides for drug delivery applications. International Journal of Pharmaceutics. 2009. Vol. 381, No. 1. pp. 34–39.
19. Sun S., Cui F., Kawashima Y., Liang N. et al. A novel insulin-sodium oleate complex for oral administration: Preparation, characterization and in vivo evaluation. Journal of Drug Delivery Science and Technology. 2008. Vol. 18, No. 4. pp. 239–243.
20. Lykins W. R., Bernards D. A., Schlesinger E. B., Wisniewski K., Desai T. A. Tuning polycaprolactone degradation for long acting implantables. Polymer. 2022. Vol. 262. 125473.
21. Chunyan Z., Lan C., Jiajia L., Dongwei S. et al. In vitro evaluation of degradation, cytocompatibility and antibacterial property of polycaprolactone/hydroxyapatite composite coating on bioresorbable magnesium alloy. Journal of Magnesium and Alloys. 2022. Vol. 10, No. 8. pp. 2252–2265.
22. Zomorodian A., Garcia M. P., Moura e Silva T., Fernandes J. C. S. et al. Biofunctional composite coating architectures based on polycaprolactone and nanohydroxyapatite for controlled corrosion activity and enhanced biocompatibility of magnesium AZ31 alloy. Materials Science and Engineering: C. 2015. Vol. 48. pp. 434–443.
23. Dhanasekaran N. P. D., Muthuvelu K. S., Arumugasamy S. K. Recent advancement in biomedical applications of polycaprolactone and polycaprolactone-based materials. Encyclopedia of Materials: Plastics and Polymers. 2022. Vol. 4. pp. 795–809.
24. Abrisham M., Noroozi M., Panahi-Sarmad M., Arjmand M. et al. The role of polycaprolactone-triol (PCL-T) in biomedical applications: A state-of-theart review. European Polymer Journal. 2020. Vol. 131. 109701.
25. Gnedenkov A. S., Sinebryukhov S. L., Filonina V. S., Plekhova N. G., Gnedenkov S. V. Smart composite antibacterial coatings with active corrosion protection of magnesium alloys. Journal of Magnesium and Alloys. 2022. Vol. 10, No. 12. pp. 3589–3611.
26. Gnedenkov A. S., Filonina V. S., Sinebryukhov S. L., Gnedenkov S. V. A superior corrosion protection of Mg alloy via smart nontoxic hybrid inhibitorcontaining coatings. Molecules. 2023. Vol. 28, No. 6. 2538.
27. Gnedenkov A. S., Sinebryukhov S. L., Filonina V. S., Egorkin V. S. et al. The detailed corrosion performance of bioresorbable Mg – 0.8 Ca alloy in physiological solutions. Journal of Magnesium and Alloys. 2022. Vol. 10, No. 5. pp. 1326–1350.
28. Suga K., Kondo D., Otsuka Y., Okamoto Y., Umakoshi H. Characterization of aqueous oleic acid/oleate dispersions by fluorescent probes and raman spectroscopy. Langmuir. 2016. Vol. 32, No. 30. pp. 7606–7612.
29. Milsom A., Squires A. M., Boswell J. A., Terrill N. J. et al. An organic crystalline state in ageing atmospheric aerosol proxies: Spatially resolved structural changes in levitated fatty acid particles. Atmospheric Chemistry and Physics. 2021. Vol. 21, No. 19. pp. 15003–15021.
30. De Veij M., Vandenabeele P., De Beer T., Remon J. P., Moens L. Reference database of Raman spectra of pharmaceutical excipients. Journal of Raman Spectroscopy. 2009. Vol. 40, No. 3. pp. 297–307.
31. Eshelman E., Daly M. G., Slater G., Dietrich P., Gravel J. F. An ultraviolet Raman wavelength for the in-situ analysis of organic compounds relevant to astrobiology. Planetary and Space Science. 2014. Vol. 93-94. pp. 65–70.