Effect of the second phase in the micro-galvanic corrosion of a commercial Mg alloy containing rare earth elements, cast WE43 alloy, was investigated in 0.6 M NaCl solution and 0.6 M Na 2 SO 4 solution by scanning electron microscopy (SEM) observations, scanning Kelvin probe force microscopy (SKPFM) analysis, hydrogen evolution, weight loss measurement, and electrochemical techniques. It is confirmed that the second phase of cast WE43 alloy is more active than Mg matrix and exhibits an anodic role in the micro-galvanic corrosion with α-Mg matrix as cathode and dissolves preferentially in Na 2 SO 4 solution, in contrast to the situation in NaCl solution. The corrosion rate of cast WE43 alloy in Na 2 SO 4 solution is much higher than that in NaCl solution, which is different from the conventional wisdom and could be attributed to the different role of the second phase in the micro-galvanic corrosion in two solutions.
Guided bone regeneration (GBR) is a prominent focus in biomedical materials research, yet few studies address practical clinical needs. GBR membranes must fulfill the “PASS” principles to be effective in surgery, but existing membranes often fall short in balancing antibacterial activity, controlled degradation, osteoinductive potential, and mechanical support. In this study, we employed laser powder bed fusion (LPBF) to fabricate a porous WE43 magnesium alloy scaffold suitable for large alveolar bone defects. We then used electrospinning and layer-by-layer (LBL) self-assembly to create a silk fibroin-based barrier membrane loaded with epigallocatechin gallate (EGCG) and polydopamine (PDA) for combined antibacterial and osteogenic functions. Laboratory tests confirmed that the WE43-F scaffolds and the EGCG/PDA-loaded membranes (SFE) are both biocompatible and bioresorbable. In vitro, they enhanced new bone formation by upregulating alkaline phosphatase (ALP) and RUNX2 gene expression while effectively inhibiting Escherichia coli and Staphylococcus aureus. In a rat maxillary defect model, the WE43-F/SFE composite system demonstrated superior bone regeneration, yielding the largest area of new bone and the most mature collagen–bone matrix, with a bone volume to total volume ratio (BV/TV) of 28.06%. In this study, we assembled WE43-F scaffolds with PDA-EGCG electrospun membranes to create a biodegradable GBR system that delivers synergistic antibacterial and osteogenic effects. Its antimicrobial efficacy and bone-regenerative capacity were confirmed through in vitro assays, cell culture experiments, antibacterial testing, and a rat mandibular defect model.
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