Fabrication of mechanically enhanced hydroxyapatite scaffold with the assistance of numerical analysis

Johnson Kehinde Abifarin,Fredah Batale Fidelis,Moshood Yemi Abdulrahim,David Ifeakachukwu Jacob,Opeyemi Kolawole Oyelakin,Emmanuel Alaba Abifarin,Muhammad Uhuotu Suleiman

doi:10.1007/s00170-021-08184-y

Abstract

Hydroxyapatite (HAp) has been found to be incompetent as it relates to its mechanical integrity, which somewhat restricts its use for load-bearing clinical applications. Several studies have been conducted doping HAp with foreign elements in order to enhance its mechanical integrity. However, it has been established that foreign elements usually trade off the phase structure and biological integrity of HAp. To avoid this challenge, this study presents a numerical analysis with the aim to fabricate a pure HAp scaffold with high mechanical strength, considering compaction and sintering protocols. The X-ray diffraction (XRD) and Fourier transformed infrared (FTIR) spectroscopy of raw bovine bones (RB) and HAp sintered at 900, 1000, and 1100 °C showed calcium phosphate contents of the bulk materials. It was also observed that increase in sintering temperature made prominent characteristic peaks of HAp phase to become narrower on the XRD patterns. The scanning electron microscope (SEM) analysis on the powdery samples showed that sintering temperature reduced HAp particle size, which resulted to the enhancement noticed in the mechanical properties of the fabricated HAp. Taguchi design analysis on the individual hardness and compressive strength revealed 1100 °C as the optimal sintering temperature, but a disparity in compaction load displaying 5 KN for high hardness and 15 KN for high compressive strength. Conversely, Taguchi grey relational analysis gave common optimal settings for high hardness and compressive strength to fabricate mechanically enhanced HAp scaffold, and are 1100 °C sintering temperature and 5 KN compaction load. Significantly, this study revealed that compaction load has a very high percentage of contribution of 90.15% compared to sintering temperature having a contribution of 7.79%. Confirmation analysis also proved that the experimental grey relational grade of 0.7824 is within 95% confidence interval.

Highlights

Hydroxyapatite (HAp) of biowastes or from synthetic source is commercially available for use in bone repair, substitution and augmentation and as scaffolds in tissue engineering for bone regeneration
It is interesting to note that the OH group band around 3500 cm-1 becomes narrower with increased in sintering temperature, which is associated to the disappearance of absorbed water after heating
Taguchi design analysis on individual mechanical properties revealed that 1100 oC was the optimal sintering temperature for individual hardness and compressive strength, but there was disparity on compaction load processing parameter level

Summary

Introduction

Hydroxyapatite (HAp) of biowastes (coral-, bovine- or marine algae derived) or from synthetic source is commercially available for use in bone repair, substitution and augmentation and as scaffolds in tissue engineering for bone regeneration. HAp is used as abrasives to roughen metal implant surfaces and as source material for depositing bioactive coatings on orthopedic and dental implants. These materials can be used as transfection agents, drug carriers and percutaneous devices. Extensive studies are geared towards methods that have the potential of enhancing the mechanical properties of HAp without overly compromising its bio-compatibility. These methods stem from tailoring the processing of the HAp powders, carefully optimizing the sintering temperature and its scaffold compaction loading (Niakan et al, 2015; Adeogun et al, 2018; Abifarin, 2021)

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Results

Conclusion