Processing methodologies for polycaprolactone-hydroxyapatite composites: A review

Biodegradable implants have shown great promise for the repair of bone defects and have been commonly used as bone substitutes, which traditionally would be treated using metallic implants. The need for a second surgery exacerbated by the stress shielding effect caused by an implant has led researchers to consider more effective, synthetic biodegradable graft substitutes. The hierarchical structures commonly designed are inspired by nature in human bones, which consist of minerals such as hydroxyapatite, a form of calcium phosphate and protein fiber. The bone graft bio-substitutes should possess a combination of properties for the purpose of facilitating cell growth and adhesion, a high degree of porosity, which would facilitate the transfer of nutrients and excretion of the waste products, and the scaffold should have high tensile strength and high toughness in order to be consistent with human tissues. Blending of polycaprolactone and hydroxyapatite has demonstrated great potential as bone substitutes. It is essential to identify a standardized processing methodology for the composite, which would result in optimum mechanical property for the biocomposite. In this study, biocomposites made of polycaprolactone (PCL) and hydroxyapatite (HAP) are reviewed for their applications in bone tissue engineering. The processing methodologies are discussed for the purpose of obtaining the porosity and pore size required in an ideal tissue scaffold. The properties of the composite can be varied based on the change in pore size, porosity, and processing methodology. This paper reviews and evaluates the methods to produce the hydroxyapatite-polycaprolactone scaffolds.