Multiphysics simulation and experimental investigation of HA and Zn-doped HA coatings on magnesium alloys for resorbable implant applications

• Published in: Materials today communications 2025-01, Vol.42, p.111241, Article 111241
• Main Authors: Barai, Binod, Boorgula, Keshava, Begam, Howa, Sarkar, Subhasish, Barui, Ananya, Kundu, Sukumar, Oraon, Buddhadeb, Mandal, Tapendu
• Format: Article
• Language: English
• Subjects: Bioimplant; Dip coating; Flow-induced corrosion; Hydroxyapatite; In vitro biocompatibility; Mg alloy; Simulation
• ISSN: 2352-4928; 2352-4928
• DOI: 10.1016/j.mtcomm.2024.111241

This study focuses on the development and characterization of hydroxyapatite (HA) and zinc-doped HA (ZnHA) coatings on magnesium (Mg) alloy using a dip coating process to minimize biodegradation and enhance bioactivity for resorbable implant applications. Numerical simulations were performed using COMSOL Multiphysics to model Flow-Induced Shear Stress (FISS11Flow Induced Shear Stress) distribution under dynamic fluid flow conditions ranging from 2 ml/min to 9 ml/min, mimicking the actual physiological environment via a 3-dimensional approach. Higher flow velocities led to increased shear stress for all samples and these findings were validated by immersion test results. The adhesivity of the coating to the substrate has been evaluated using ASTM standard procedures. Potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) tests were conducted on both uncoated and coated samples, revealing that the coatings significantly improved corrosion resistance. Characterization of the coated surfaces involved analyses using X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), Raman spectroscopy, and X-ray photoelectron spectroscopy (XPS) to determine phase composition and elemental content. Surface morphology was examined with scanning electron microscopy (SEM) and a 3D profilometer, while corrosion products were analyzed using SEM and energy-dispersive X-ray spectroscopy (EDS). Further biological assessments evaluated the antimicrobial properties, hemocompatibility, cell viability (MTT assay), and cell morphology (DAPI imaging) of the coated samples. Overall, the findings demonstrate that HA and ZnHA coatings can decrease the corrosion rate by 73.33 % and 82.45 % respectively, and enhance the biological response of Mg alloy, initially due to the presence of a biologically favorable barrier layer of HA and subsequently due to Zn-induced alterations in the surface composition, crystal structure, and morphology of the barrier layer, making it suitable for biomedical applications. [Display omitted]