Synthesis, characterization, and mechanical properties of nano metal-substituted hydroxyapatite and metal oxides/hydroxyapatite nanocomposites

Title : Synthesis, characterization, and mechanical properties of nano metal-substituted hydroxyapatite and metal oxides/hydroxyapatite nanocomposites

Abstract:

Addressing metal deficiencies in synthetic hydroxyapatite (Hap) is proposed as a way to enhance Hap's mechanical properties. Previous studies suggest that incorporating metals or metal oxides improves fracture toughness and reduces brittleness. This study investigates the effects of two metal incorporation methods on Hap's mechanical properties: The first method consists of incorporating metals by replacing some calcium in the Hap structure via substitution. The second method consists of modifying Hap by preparing (metal oxide)/Hap composites. Nano powders of pure Hap, substituted Hap (Ca10-xMx(PO4)6(OH)2), and (MO)x/Hap composites (M = Mg, Zn) with x = 0.0, 0.1, and 0.3 were synthesized using a low-temperature technique. (ZnO)x/Hap nanocomposites were prepared by precipitating zinc oxide nanoparticles in a nano Hap slurry, while (MgO)x/Hap composites were prepared by precipitating Hap nanoparticles in a diluted nano MgO slurry. 

XRD, FTIR, and SEM analyses identified Hap as the only crystalline phase present, with a uniform morphology and particle sizes ranging from 40 to 100 nm. EDAX analysis confirmed the presence of Ca, P, and O in pure Hap, and Ca, P, O, Mg, and Zn in both substituted Hap and (MO)x/Hap composites. Mechanical testing, which included breaking force, work of fracture, and brittleness/ductility evaluations, demonstrated that modifying Hap with metal oxides significantly enhanced its mechanical properties compared to calcium substitution for the same quantity and type of incorporated metal. Optimal mechanical strength was observed in (MO)x/Hap composites with a 0.1:1.0 MO:Hap mole ratio (M = Mg, Zn).

Biography:

Azzedine Bensalem, Full Professor. Chairman, Natural Sciences. Ph.D. from Université de Nantes (France), Post-doc at Polytechnic University of New York. Visiting Follow at Ecole Polytechnique, France. Chairman of the Natural Sciences (chemistry, biochemistry, math, and physics). Prior to this appointment, served as Chairman of the department of Chemistry and Biochemistry for 12 years, Chaired the LIU committee of Chairs for 2 years, and for several years, Chaired the department Appointment Reappointment Promotion and Tenure committee. 

Azzedine Bensalem's areas of research include largely focused in the area of Materials Chemistry. At the present time, my interest in this area lies mainly in the development of new strategies for the custom design of materials with derived and controllable properties, and of new methods of synthesis. With this in mind, my focus has always been on developing low temperature synthetic techniques. Low temperature routes for the synthesis of new materials are of great interest, since kinetics usually dominates thermodynamics under these conditions. 

The use of low temperatures allows the preparation of solids with very fine particles and very high surface area. These are very desirable properties in a number of applications. Several materials of great technological interest have been prepared in my research laboratory. Indeed, we prepared materials such as Transition metal oxides as well as lithiated transition metal oxides with applications in lithium batteries. The same synthetic technique with a slight modification was used to prepare Nano-materials for electronic and biomedical applications. Recent research work focused on synthesizing Nano-bioceramics with improved bactericidal and mechanical properties for bone-engineering application.