Laser-zoned treatment of magnesium surfaces with predictable degradation applications

Abstract

Magnesium metal is a promising material for medical applications due to its biocompatibility and similar modulus of elasticity to human bone. However, its complex corrosion process must be addressed before it can be used clinically to match post-implantation tissue repair. This study aims to regulate material degradation by utilizing laser surface treatment. The surface of pure magnesium was modified using nanosecond and femtosecond laser methods to create various micro-nanostructures, such as chain, streak, column, and groove structures. Surface roughness and wettability tests revealed that the groove structures had higher roughness values. All structures exhibited hydrophilicity, but the femtosecond laser-generated structures were more hydrophilic. Electrochemical tests and immersion experiments demonstrated that femtosecond laser modification significantly improved the corrosion resistance of magnesium metal compared to polished samples. Cytotoxicity experiments showed that the laser-treated magnesium was not cytotoxic. Based on the results, we constructed various structures on the magnesium rods in different regions. As a result, the rods exhibited multi-stage biodegradation behavior in simulated body fluids (SBF). This study presents a novel approach to controlling the degradation sequence of medical metals.