Controlled biodegradation of magnesium alloy in physiological environment by metal organic framework nanocomposite coatings.

Magnesium-based implants (MBIs) have recently attracted great attention in bone regeneration due to elastic modulus similar to bone. Nevertheless, the degradation rate and hydrogen release of MBIs in the body have to be tackled for practical applications. In the present study, we present a metal-organic framework (MOF) nanoplates to reduce the degradation rate of AZ91 magnesium alloy. Zeolitic imidazolate frameworks (ZIF-8) with a specific surface area of 1789 m2 g-1 were prepared by solvothermal methods, and after dispersion in a chitosan solution (10% w/w), the suspension was electrospun on the surface of AZ91 alloy. Studying the degradation rate in simulated body fluid (SBF) by electrochemical analysis including potentiodynamic polarization and electrochemical impedance spectroscopy reveals that the degradation rate of the surface-modified implants decreases by ~ 80% as compared with the unmodified specimens. The reduced alkalization of the physiological environment and hydrogen release due to the implant degradation are shown. In vitro studies by fibroblasts and MG63 osteosarcoma cells exhibit improved cell adhesion and viability. The mechanisms behind the improved degradation resistance and enhanced bioactivity are presented and discussed. Surface modification of MBIs by MOF-chitosan coatings is a promising strategy to control the biodegradation of magnesium implants for bone regeneration.