Date of Graduation

5-2025

Document Type

Thesis

Degree Name

Bachelor of Science in Biomedical Engineering

Degree Level

Undergraduate

Department

Biomedical Engineering

Advisor/Mentor

Elsaadany, Mostafa

Abstract

Bone fractures and complete joint replacements are becoming more common, primarily because of accidents and age-related issues. Conventional solutions to treat these orthopedic injuries involve inert metal alloys to correct bone fractures until the healing process is complete, where a secondary revision surgery is then required to remove the implant. Issues regularly associated with these solutions include stress shielding, bone resorption, infection, inflammation, and implant loosening. Magnesium (Mg)-based nanocomposites offer promising potential as an alternative to commonly used metal alloys because of their favorable mechanical properties and biocompatibility. A particularly advantageous property of Mg is its natural biodegradation in vivo, meaning the implant will dissolve once healing has been completed, eliminating the need for revision surgeries. However, Mg’s naturally high corrosion rate presents significant challenges for these applications, including compromised mechanical stability and biocompatibility. This research investigates the effects of boron nitride (BN) and silicon carbide (SiC) nanoparticle reinforcement on the degradation behavior, mechanical strength, microstructural properties, and biocompatibility of Mg-based nanocomposites. The influence of adding each nanoparticle individually showed a significantly positive effect on mechanical and corrosion properties in current literature. However, further investigation into the effect of adding these two nanoparticles together into the magnesium matrix has yet to be conducted. Therefore, this study investigates the influence of adding these two nanoparticles in equal volume percentages to create hybrid Mg-based nanocomposites to more comprehensively assess their combined influence on mechanical properties, corrosion resistance, and biocompatibility. Characterization techniques included porosity measurements, Vickers microhardness testing, contact angle analysis, scanning electron microscopy with energy dispersive X-ray spectroscopy (SEM/EDX), and X-ray diffraction (XRD) analysis. Biocompatibility was assessed through cell viability assays and a PFA cell fixation study, while corrosion performance was evaluated via SEM imaging, electrochemical corrosion tests, and immersion testing in complete αMEM, followed by inductively coupled plasma optical emission spectroscopy (ICP-OES). The Zk60-0.5%BN-0.5%SiC nanocomposite exhibited improved hardness, refined grain structure, and strong interparticle bonding with minimal porosity. SEM and EDX analyses confirmed uniform nanoparticle dispersion and grain boundary reinforcement. However, the same composite also showed increased corrosion susceptibility, as indicated by higher pH shifts, greater Mg ion release, and more pronounced Mg(OH)₂ surface deposits during SEM characterization. Biocompatibility assays revealed moderate cytotoxicity in both the Pure Zk60 and Zk60-0.5%BN-0.5%SiC groups, with reduced cell adhesion linked to elevated corrosion rates in the latter. Despite these challenges, the mechanical benefits and early-stage cell attachment suggest strong potential for orthopedic use. Future work should focus on optimizing nanoparticle volume fractions and applying corrosion-resistant coatings to enhance the long-term viability of Mg-based nanocomposites in clinical settings. Overall, the Mg nanocomposites reinforced with BN and SiC nanoparticles demonstrated enhanced mechanical and microstructural properties suitable for orthopedic implants, but the increased corrosion rate needs to be addressed before clinical applications.

Keywords

magnesium; orthopedics; nanocomposite; bone implants; corrosion; biocompatibility

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Available for download on Friday, April 24, 2026

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