A nano-sandwich construct built with graphene nanosheets and carbon nanotubes enhances mechanical properties of hydroxyapatite–polyetheretherketone scaffolds

Abstract

A nano-sandwich construct was built by combining two-dimensional graphene nanosheets (GNSs) and one-dimensional carbon nanotubes (CNTs) to improve the mechanical properties of hydroxyapatite–polyetheretherketone (HAP–PEEK) scaffolds for bone tissue engineering. In this nano-sandwich construct, the long tubular CNTs penetrated the interlayers of graphene and prevented their aggregation, increasing the effective contact area between the construct and matrix. The combination of GNSs and CNTs in a weight ratio of 2:8 facilitated the dispersion of each other and provided a synergetic effect in enhancing the mechanical properties. The compressive strength and modulus of the scaffolds were increased by 63.58% and 56.54% at this time compared with those of HAP–PEEK scaffolds, respectively. The carbon-based fillers, pulling out and bridging, were also clearly observed in the matrix. Moreover, the dangling of CNTs and their entangling with GNSs further reinforced the mechanical properties. Furthermore, apatite layer formed on the scaffold surface after immersing in simulated body fluid, and the cells attached and spread well on the surface of the scaffolds and displayed good viability, proliferation, and differentiation. These evidence indicate that the HAP–PEEK scaffolds enhanced by GNSs and CNTs are a promising alternative for bone tissue engineering.

Keywords:

• scaffold
• mechanical properties
• apatite-forming ability
• cell culture
• tissue engineering

Acknowledgments

This work was supported by the following funds: the Natural Science Foundation of China (51575537, 81572577); Overseas, Hong Kong & Macao Scholars Collaborated Researching Fund of National Natural Science Foundation of China (81428018); Hunan Provincial Natural Science Foundation of China (14JJ1006, 2016JJ1027); the Project of Innovation-driven Plan of Central South University (2015CXS008, 2016CX023); the Open-End Fund for the Valuable and Precision Instruments of Central South University; the fund of the State Key Laboratory of Solidification Processing in NWPU (SKLSP201605); the fund of the State Key Laboratory for Powder Metallurgy; and the Fundamental Research Funds for the Central Universities of Central South University.

Disclosure

The authors report no conflicts of interest in this work.