Impact of Zn-Modified Hydroxyapatite Whiskers on Physicochemical and Biological Properties of Poly(ε-Caprolactone) Composites Intended for Implantable Medical Devices

Abstract

Poly(ε-caprolactone) (PCL)-hydroxyapatite (HAP) biocomposites were produced by thermal processing to test the impact of HAP addition on the physicochemical and biological properties of PCL. Two different HAPs: zinc-modified and unmodified, were added to the polymer matrix to enhance their biocompatibility, surface properties, and antimicrobial activity. The overall properties of biocomposites were assessed by thermal and mechanical analysis, while their structure and morphology were assessed by electron microscopy and infrared spectroscopy. A short-term degradation process of the composites in terms of their medical application was carried out, and biocompatibility was investigated regarding cytocompatibility, immunocompatibility, and bactericidal activity. PCL/HAP composites with 15 wt.% HAP offer the best-balanced properties with a moderate decrease in mechanical strength, cytocompatibility, and a moderate increase in antimicrobial activity. All the composites show high cytocompatibility with both L929 fibroblasts and hFOB 1.19 human fetal osteoblasts. Zn modification promoted their antimicrobial properties, and they have been proven safe for use in a short degradation test. Therefore, the PCL/HAP and PCL/HAP_Zn biocomposites have potential for medical applications, especially for bone regeneration.