writer：Zongliang Wang, Yu Wang, Yoshihiro Ito, Peibiao Zhang & Xuesi Chen.
keywords：Hydroxyapatite, poly(L-lactide), nanocomposite,biodegradation
source：期刊
specific source：Scientific Reports, 2016, accepted, DOI: 10.1038.
Issue time：2016年
Abstract   Composite of nano-hydroxyapatite (n-HAP) surface grafted with poly(L-lactide) (PLLA) (g-HAP) showed improved interface compatibility and mechanical property for bone fracture fixation. In this paper, in vivo degradation of n-HAP/PLLA and g-HAP/PLLA composite implants was investigated. The mechanical properties, molecular weight, thermal properties as well as crystallinity of the implants  were measured. The bending strength of the n- and -HAP/PLLA composites showed a marked reduction from an initial value of 102 and 114 MPa to 33 and 24 MPa at 36 weeks, respectively. While the bending strength of PLLA was maintained at 80 MPa at 36 weeks compared with initial value of 107 MPa. The impact strength increased over time especially for the composites. Significant differences in  the molecular weight were seen among all the materials and g-HAP/PLLA appeared the fastest rate of decrease than others. Environmental scanning electron microscope (ESEM) results demonstrated that an apparently porous morphology full of pores and hollows were formed in the composites. The results indicated that the in vivo degradation of PLLA could be accelerated by the g-HAP nanoparticles. It  implied that g-HAP/PLLA composites might be a candidate for human non-load bearing bone fracture fixation which needs high initial strength and fast degradation rate.