Mechanical Properties of Differently Nanostructured and High-Pressure Compressed Hydroxyapatite-Based Materials for Bone Tissue Regeneration

Abstract

Hydroxyapatite (HAp) has long been considered the gold standard in the biomedical field, considering its composition and close resemblance to human bone. However, the brittle nature of hydroxyapatite (HAp) biomaterial, constrained by its low fracture toughness (of up to 1.2 vs. 2–12 MPa m1/2 of human bone), remains one of the significant factors impairing its use in bone regeneration. In the present study, HAp nanoparticles synthesized by the solid-state (SHAp) and sonochemical (EHAp) approaches using eggshell-derived calcium hydroxide and ammonium dihydrogen orthophosphate as precursors are compared with those synthesized using commercially available calcium hydroxide and ammonium dihydrogen orthophosphate as precursors (CHAp) employing sonochemical method. The HAp samples were then compressed into compact materials using a uniaxial high-pressure compression technique at a preoptimized load and subsequently characterized for mechanical properties using the Vickers indentation method and compressive strength testing. The analysis revealed that the material with smaller particle size (30–40 nm) and crystalline nature (EHAp and CHAp) resulted in mechanically robust materials (σm= 54.53 MPa and 47.72 MPa) with high elastic modulus (E = 4011.1 MPa and 2750.25 MPa) and density/hardness-dependent fracture toughness (σf= 4.34 MPa m1/2and 6.57 MPa m1/2) than SHAp (σm =28.40 MPa, E = 2116.75 MPa, σf = 5.39 MPa m1/2). The CHAp material was found to be the most suitable for applications in bone regeneration.

Review of Physical, Mechanical, and Biological Characteristics of 3D-Printed Bioceramic Scaffolds for Bone Tissue Engineering Applications

“…When the scaffold is to be implanted in cancellous bone, the porosity should be 60–90% with a compression strength of 2–12 MPa. If it is implanted in trabecular bone, it can have 10–30% porosity with a compressive strength of 45–130 MPa to avoid failure . The mechanical properties of cancellous and cortical bone are given in Table .…”

“…Several studies have been conducted to find the compromise between optimal porosity and mechanical strength. Egg-shell-derived nano-Hap was found to have higher mechanical strength than chemical-derived Hap . 3D gel printing (3DGP) is used to fabricate the Hap scaffold with suitably interconnected macroporosity and mechanical strength.…”

“…Egg-shell-derived nano-Hap was found to have higher mechanical strength than chemical-derived Hap. 53 3D gel printing (3DGP) is used to fabricate the Hap scaffold with suitably interconnected macroporosity and mechanical strength. The compression strength of 16.77 MPa was attained for the porosity of 52.26%, thus making it suitable for implanting in cancellous bone.…”

“…If it is implanted in trabecular bone, it can have 10−30% porosity with a compressive strength of 45−130 MPa to avoid failure. 53 The mechanical properties of cancellous and cortical bone are given in Table 2. Imparting mechanical properties such as compression strength, fatigue strength, fracture strength, etc.…”

Hydroxyapatite-collagen- carboxylic carbon quantum dot composite loaded with chrysin supported the proliferation and differentiation of human bone marrow derived mesenchymal stem cells

“…They covered the Ions doped HAP, HAP/polymeric composites, surface modified HAP, and their polymeric composition (Shi et al, 2021). Despite the advantage of HAP in the bone healing process, HAP has not enlarged its reputation in the orthopedic field due to its brittleness and poor molding ability (Ingole et al, 2021). To overcome this issue, we have enhanced the mechanical strength of the HAP with collagen (COL) protein.…”