IN VITRO BIOMINERALIZATION AND DEGRADATION OF MG DEGRADABLE IMPLANTS BY LASER PROCESSING

Magnesium based materials have become attractive candidates for biodegradable temporary implants because of their similarity to bone properties compared to other alloys, their good biocompatibility, nontoxicity and biodegradability. However, their slow formation of bone minerals including hydroxyapatite, known as biomineralization and rapid degradation in a physiological environment inhibits its usage as an implant material. The objective of this research is to investigate the impact of laser processing on the surface of magnesium AZ31B alloys on its biomineralization and degradation in a simulated physiological environment by immersion in simulated body fluid (SBF). Laser processing offers rapid heating and cooling, controllable and reproducible refinement of grain size and increase of surface roughness. It was observed that laser processing with 3.18x10⁶ J/mm² reduces grain size by 25 times and increases surface roughness 11 times. Consequently, the wettability, which measures interaction between AZ31B surface and SBF on it, also improved. Wettability assessed by contact angle measurements was found to increase significantly. In vitro bioactivity and degradation of the laser processed samples studied by immersing in SBF showed rapid mineralization with the major bone compound hydroxyapatite (Ca₅(PO₄)₃OH) formed. Calcium and Phosphate deposition increases significantly. Furthermore, the rapid mineralization serves as an added barrier to processed AZ31B magnesium and impedes magnesium corrosion. As a result, the mineralization rate slightly exceeds the corrosion, promising an excellent biodegradable implant material.