Biomimetic gelatine coating for less-corrosive and surface bioactive Mg–9Al–1Zn alloys

Magnesium (Mg)-based alloys have been emerging as innovative orthopedic materials due to their light weight and excellent biocompatibility. However, their too rapid degradation and subsequent loss of mechanical integrity before the bone tissue regeneration limits their applications. The presented study introduces in situ cross-linked gelatine (GEL) as a biomimetic coating onto Mg-9Al-1Zn-based alloys by carbodiimide chemistry and dip-coating. The bulk and surface morphology, chemistry, and bioactivity, as well as the corrosion behavior of uncoated and coated alloys were investigated in simulated body fluid (SBF) solution via in vitro testing and using various analytical techniques. The results revealed that the GEL coating mitigates the corrosion (from ∼2.08 to ∼1.19 mm/year) by forming a protective interface layer between the alloy surface and SBF solution, generating a bio-safer alkaline pH environment (pH ≈ 8.3), which minimizes the material resorption. GEL presence also stimulates the mineralization with calcium phosphate compounds, being patterned by its orientation and random coil conformation.