Abstract
Poly(1,6-bis-(p-carboxyphenoxy hexane)-co-(sebacic anhydride)) (PANH), is a polyanhydride copolymer which has good biocompatibility, and degrades to non-toxic products with a predictable rate of degradation. Nano-sized hydroxyapatite (nHAP) is a well-known biomaterial which has been applied in bone regeneration due to its osteoconductivity. However, nano-sized HAP has poor colloidal stability which leads to agglomeration when incorporated into polymeric composites. In this work we describe the surface grafting of poly(ɛ-caprolactone) to HAP (PCL-gHAP) to improve the interfacial adhesion and dispersion of HAP particles in a PANH matrix to form a composite material. The use of scanning electron microscopy-backscattered electron (SEM-BSE) detector and the combination of focused ion beam (FIB)/ transmission electron microscopy (TEM) provided a powerful approach for observing the dispersion of HAP particles in the polymer matrix. We show that surface modification of gHAP with PCL improved the homogeneity of the dispersion of PCL-gHAP particles in the composites and affected the composite morphology during hydrolytic degradation. Composites with high HAP content displayed high compressive strength and a fast rate of degradation. The PCL-gHAP/PANH composites showed superior maintenance of mechanical properties compared with nHAP/PANH composites during degradation. A preliminary in vivo study on rat calvaria repair, demonstrated the superior performance of PCL-gHAP/PANH composites. These results suggest that the newly developed PCL-gHAP/PANH composite materials may be a potential substrate for bone tissue engineering.