Effect of surface modification on interfacial behavior in bioabsorbable magnesium wire reinforced poly-lactic acid polymer composites

Abstract

The mechanical behavior, corrosion mechanisms, and cytocompatibility at the interface of magnesium wires reinforced poly-lactic acid polymer composites were studied by in vitro degradation study of 180 days. Surface modification of Mg wires by plasma-electrolytic oxidation improved the interface shear strength from 10.9 MPa to 26.3 MPa which decreased to 8 MPa and 13.6 MPa in Mg/PLA and PEO-Mg/PLA composites, respectively, after 42 days of in vitro degradation. Cross-sections of the composite showed good cytocompatibility, although the cells tended to migrate towards the PLA regions and avoided the surface of the Mg wires. Corrosion of Mg wires (without surface modification) was very fast in composite while corrosion of surface-modified Mg wires was significantly reduced, hydrogen gas was suppressed and only 3% mass loss of Mg wires was found after 180 days. Finally, the corrosion mechanisms at interface were discussed for both composites.

Medical grade 3D printable bioabsorbable PLDL/Mg and PLDL/Zn composites for biomedical applications

“…Interestingly, the theoretical volume of hydrogen expected to be released from the Mg content in the composite was 84.6 mL, much higher than the 47 mL measured experimentally. This difference is in agreement with previous reports 45,46 and has been attributed to oxygen reduction reactions likely to occur during slow corrosion of Mg 47,48 or that the hydrogen bubbles were trapped underneath the sample or in the funnel. 45 Scanning electron microscopy was used in order to reveal the degradation mechanisms involved of the three materials over time.…”

“…It has also been shown that the polymer matrix is subjected to an accelerated degradation in alkaline environment, even more than in an acidic environment. 48,50,55 Furthermore, increasing the volume of the particle due to Mg oxidation leads to crack formation and facilitates the entry of water in the case of PLDL + Mg + PEG. 49 A similar process was observed, although at a slower rate, in the PLDL + Zn composite.…”