Ion-bombardment-driven surface modification of porous magnesium scaffolds: Enhancing biocompatibility and osteoimmunomodulation

Porous Mg scaffolds are promising for bone repair but are limited by high corrosion rates and challenges in preserving coating integrity. We used Directed Plasma Nanosynthesis (DPNS) at 400 eV and a fluence of 1 x 10(18) cm(-2) to augment the bioactivity and corrosion resistance of porous Mg scaffolds, maintaining their overall material integrity. DPNS creates nanostructures that increase surface area, promote apatite nucleation, and enhance osseointegration, improving the bioactivity and corrosion resistance of porous Mg scaffolds without compromising their structure. Our findings indicate a decrease in surface roughness, with pre-irradiated samples having Rq = 60.4 +/- 5.3 nm andRa = 48.2 +/- 3.1 nm, and post-DPNS samples showing Rq = 36.9 +/- 0.3 nm andRa = 28.6 +/- 0.8 nm. This suggests changes in topography and wettability, corroborated by the increased water contact angles (CA) of 129.2 +/- 3.2 degrees. The complexity of the solution influences the CA: DMEM results in a CA of 120.4 +/- 0.1 degrees, while DMEM + SBF decreases it to 103.6 +/- 0.5 degrees, in contrast to the complete spreading observed in non-irradiated samples. DPNS-treated scaffolds exhibit significantly reduced corrosion rates at 5.7 x 10(-3) +/- 3.8 x 10(-4) mg/cm(2)/day, compared to the control's 2.3 x 10(-2) +/- 3.2 x 10(-4) mg/cm(2)/day over 14 days (P < 0.01). The treatment encourages the formation of a Ca-phosphate-rich phase, which facilitates cell spreading and the development of focal adhesion points in hBM-MSCs on the scaffolds. Additionally, J774A.1 murine macrophages show an enhanced immune response with diminished TNF-alpha cytokine expression. These results offer insights into nanoscale modifications of Mg-based biomaterials and their promise for bone substitutes or tissue engineering scaffolds.