Evaluation of Corrosion and Antimicrobial Properties of Polycaprolactone-Hydroxyapatite/ Tetracycline Coating on Magnesium Alloy for Orthopedic Applications

Magnesium alloys have attracted special attention in the field of orthopedic implants due to their mechanical properties close to natural bone, high biocompatibility, and biodegradability that eliminates the need for secondary surgery for implant removal. However, the rapid corrosion and high degradation rate of magnesium remain one of the main challenges in its clinical applications. One effective solution to overcome this problem is to modify the surface of magnesium alloys using biocompatible coatings Therefore, in this study, the modification of the magnesium surface by polycaprolactone (PCL) containing different percentages of hydroxyapatite (HA) and tetracycline (TC) was investigated in order to improve corrosion resistance and antibacterial properties. The results showed that the PCL-HA/TC composite coating has a dense structure with great bonding to the substrate. However, the contact angle of the coated samples was significantly reduced to 81° by adding HA and TC, which has an effective effect on the bioactivity of the coated Mg alloy. Electrochemical studies indicated that the corrosion resistance of Mg alloy was significantly increased after the application of PCL coatings containing HA and TC. The polarization test also confirmed this finding and showed that the coated samples had higher corrosion resistance than the uncoated sample. In addition, antibacterial tests showed that the PCL-HA/TC coating with a higher percentage of TC exhibited stronger antimicrobial activity, which confirms the high efficiency of this coating in providing simultaneous corrosion protection and disinfection.