Aloe Polysaccharide/Microarc Oxidation Composite Coating on AZ31 Magnesium Alloy: Synergistic Enhancement of Corrosion Resistance and Cytocompatibility for Biomedical Applications

A aloe polysaccharide/microarc oxidation composite coating (AP/MAO) was fabricated on AZ31 magnesium alloy via microarc oxidation and dip coating to enhance corrosion resistance and cytocompatibility. SEM, EDS, XRD, and FT-IR showed that the porous MAO layer with micropores and microcracks was effectively sealed by aloe polysaccharides, forming a 14.38 μm thick double-layer coating. Scratch tests indicated strong adhesion (critical load Lc3 = 33.14 N). Water contact angle measurements demonstrated significantly improved hydrophilicity. Electrochemical tests revealed that the AP/MAO coating shifted the corrosion potential positively by 220 mV (from −1.698 V to −1.478 V) and reduced the corrosion current density by nearly three orders of magnitude (from 2.67 × 10 -5 to 3.25 × 10 -8 A·cm -2 ). Hydrogen evolution and immersion experiments further confirmed the enhanced corrosion resistance. Cytocompatibility evaluation showed that MC3T3-E1 cell proliferation on the AP/MAO coating exceeded 85%, significantly higher than on untreated AZ31, with well-preserved cell morphology. Overall, the AP/MAO composite coating synergistically improves corrosion resistance and cytocompatibility, offering a new surface modification strategy for medical magnesium alloy implants.