Bio-Resorption Control of Magnesium Alloy AZ31 Coated with High and Low Molecular Weight Polyethylene Oxide (PEO) Hydrogels

Raffaella Aversa; Valeria Perrotta; Chao Wang; Antonio Apicella

doi:10.3390/gels9100779

Bio-Resorption Control of Magnesium Alloy AZ31 Coated with High and Low Molecular Weight Polyethylene Oxide (PEO) Hydrogels

Gels. 2023 Sep 25;9(10):779. doi: 10.3390/gels9100779.

Authors

Raffaella Aversa¹, Valeria Perrotta¹, Chao Wang^{2

3}, Antonio Apicella¹

Affiliations

¹ Advanced Materials Lab, Department of Architecture and Industrial Design, University of Campania, Via San Lorenzo, 81031 Aversa, Italy.
² Key Laboratory of Biomechanics and Mechanobiology, Ministry of Education, Beijing Advanced Innovation Center for Biomedical Engineering, School of Biological Science and Medical Engineering, School of Engineering Medicine, Beihang University, No. 37, Xueyuan Road, Beijing 100083, China.
³ State Key Laboratory of Virtual Reality Technology and Systems, Beihang University, No. 37, Xueyuan Road, Beijing 100083, China.

Abstract

Magnesium AZ31 alloy has been chosen as bio-resorbable temporary prosthetic implants to investigate the degradation processes in a simulating body fluid (SBF) of the bare metal and the ones coated with low and high-molecular-weight PEO hydrogels. Hydrogel coatings are proposed to control the bioresorption rate of AZ31 alloy. The alloy was preliminary hydrothermally treated to form a magnesium hydroxide layer. 2 mm discs were used in bioresorption tests. Scanning electron microscopy was used to characterize the surface morphology of the hydrothermally treated and PEO-coated magnesium alloy surfaces. The variation of pH and the mass of Mg²⁺ ions present in the SBF corroding medium have been monitored for 15 days. Corrosion current densities (I_corr) and corrosion potentials (E_corr) were evaluated from potentiodynamic polarisation tests on the samples exposed to the SBF solution. Kinetics of cumulative Mg ions mass released in the corroding solution have been evaluated regarding cations diffusion and mass transport parameters. The initial corrosion rates for the H- and L-Mw PEO-coated specimens were similar (0.95 ± 0.12 and 1.82 ± 0.52 mg/cm²day, respectively) and almost 4 to 5 times slower than that of the uncoated system (6.08 mg/cm²day). Results showed that the highly swollen PEO hydrogel coatings may extend into the bulk solution, protecting the coated metal and efficiently controlling the degradation rate of magnesium alloys. These findings focus more research effort on investigating such systems as tunable bioresorbable prosthetic materials providing idoneous environments to support cells and bone tissue repair.

Keywords: PEO; anomalous sorption; biocompatibility; bioresorbable implants; corrosion; magnesium alloy; swelling.

Grants and funding

This work was supported by the National Natural Science Foundation of China (Grant Nos. 12072055, 11872135, U20A20390), the Natural Science Foundation of Beijing (Grant No. L212063), and the Fundamental Research Funds for the Central Universities, the 111 Project (No. B13003), CAMS Innovation Fund for Medical Sciences (CIFMS) under Grant 2019-I2M-5-016, “Belt and Road” Innovative Talent Exchange Program for Foreign Experts of the State Administration of Foreign Experts Affairs (No. DL2023177001L).