A study on combination of alkaline treatment and PLA/f-CNTs composite coating on corrosion, biocompatibility and antibacterial activity of Mg alloy

The present study explores the effect of combined alkaline treatments (NaOH) and the incorporation of functionalized carbon nanotubes (f-CNTs) into poly(lactic acid) (PLA) composite coatings on the corrosion resistance, biocompatibility, and antibacterial efficacy of AZ31 magnesium (Mg) alloy. Various pretreatment techniques and coating layers have been found to exert considerable influence on the phase composition, morphology, thickness, wettability, as well as corrosion resistance, and biological characteristics of the Mg alloy. The formation of an Mg(OH)2 layer on alkaline-treated Mg alloy has proven to enhance hydrophilicity, corrosion resistance, and biocompatibility. Moreover, the findings highlight that incorporating f-CNTs into PLA improves the corrosion resistance, cytocompatibility, and antibacterial activity of Mg alloy in physiological solutions and the extent of these improvements is related to the quantity of f-CNTs present in the composite coating. Additionally, the outcomes have shown that the inclusion of f-CNTs promotes the formation of carbonate based precipitates during a 14-day immersion in Ringer's solution. Overall, the combination of alkaline treatments and the PLA/f-CNTs composite coating is showcased as a promising surface modification approach for orthopedic applications.