The comparison of biocompatibility and osteoinductivity between multi-walled and single-walled carbon nanotube/PHBV composites.

The applications of poly (3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) in tissue engineering have been widely studied. This study aimed to compare the biocompatibility and osteoinductivity of single-walled carbon nanotubes (SWCNTs)/PHBV composites with multi-walled CNTs (MWCNTs)/PHBV composites. CNTs were dispersed in PHBV by ultrasonication and composites were created using thermal injection moulding. In order to test their biocompatibility and osteoinductivity. Rat osteoblasts (rOBs) were then cultured and seeded on the composites. The composites were implanted in rat femoral bone defects. Our results showed that lower weight percentages of SWCNTs and MWCNTs (2-4%) improved both their mechanical and thermal decomposition properties. However, further reduction of rOBs cell death was observed in MWCNTs/PHBV. SWCNTs were shown to upregulate the expression of Runx-2 and Bmp-2 in early stage significantly, while MWCNTs showed a stronger long-term effect on Opn and Ocn. The in vivo result was that MWCNTs/PHBV composites induced intact rounding new bone, increased integration with new bone, and earlier completed bone remodeling when compared with SWCNTs. Immunohistochemistry also detected higher expression of RUNX-2 around MWCNTs/PHBV composites. In conclusion, there were no differences observed between SWCNTs and MWCNTs in the reinforcement of PHBV, while MWCNTs/PHBV composites showed better biocompatibility and osteoinductivity both in vitro and in vivo.