Abstract
To enhance the bioactivity of poly(lactic acid) (PLA), a potential bone repair material, without the lowering of mechanical strength, hydroxyapatite (HA) was introduced in the form of nanofibers as the filler for application in spinal implant materials. HA nanofibers (HANF) with aspect ratio as high as ~100 were synthesized by controlling the starting pH of the reaction. While the tensile and flexural strength of PLA/HANF composites were enhanced compared with those of PLA resin, and were higher for the composites with HANF of higher aspect ratio. To further strengthen the composites, HANF was grafted with PLA chain to form HANF-g-PLA, which could improve the interface between the HANF and matrix PLA. PLA/HANF-g-PLA composites showed even higher tensile and flexural strength than PLA/HANF composites, apparently due to the better dispersion and interfacial adhesion. The composite containing 10 wt% HANF-g-PLA showed the flexural strength of 124 MPa, which was 25% higher than that of PLA resin. In the bioactivity test using a simulated body fluid solution, the rate and uniformity of the apatite growth were observed to be higher for the composites with HANF, and were even higher for those with HANF-g-PLA. This study suggested the possibility of using the PLA/HANF-g-PLA composite in the field of spinal implant materials.
Highlights
Metals like titanium and magnesium have been the most popular material for spinal implants by virtue of their superior mechanical strength and processability
The biodegradable polymers considered for biomedical applications have been poly(lactic acid) (PLA), poly(glycolic acid) (PGA), and polycaprolactone (PCL) [3]
The application of PCL to spinal implant materials has been limited because the mechanical strength of PCL was much lower than that of human spine bone [7]
Summary
Metals like titanium and magnesium have been the most popular material for spinal implants by virtue of their superior mechanical strength and processability. The application of PCL to spinal implant materials has been limited because the mechanical strength of PCL was much lower than that of human spine bone [7]. PLA’s mechanical strength including flexural strength required for spinal implants was lower than that of human spine bone. Despite the improved dispersion of HA and interfacial adhesion between HA and PLA matrix in these efforts, the increase in mechanical properties such as tensile strength and flexural strength were less than 5% compared to those of PLA. 10 wt% of hydroxyapatite nanofiber (HANF), the biaxial flexural strength of the composite increased by 22% compared to that of dental resin even without surface modification [26]. HA was synthesized in the form of nanofiber, and grafted by PLA to improve the interfacial adhesion between HANF and PLA and the dispersion of HANF in the composites. The effect of aspect ratio and grafting of PLA on the mechanical properties and bioactivity of the composites were examined
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
