The use of carbon nanotubes to reinforce 45S5 bioglass-based scaffolds for tissue engineering applications

Abstract

Bioglass has been used for bone-filling material in bone tissue engineering, but its lean mechanical strength limits its applications in load-bearing positions. Carbon nanotubes (CNTs), with their high aspect ratio and excellent mechanical properties, have the potential to strengthen and toughen bioactive glass material without offsetting its bioactivity. Therefore, in this research, multiwall carbon nanotube (MWCNT)/45S5 Bioglass composite scaffolds have been successfully prepared by means of freeze casting process. 45S5 Bioglass was synthesized by the sol-gel processing method. The obtained material was characterized with X-ray powder diffraction (XRD). The mechanical properties of the scaffolds, such as compression strength and elastic modulus, were measured. Finally, compared with the scaffolds prepared by 100% 45S5 Bioglass powders, the addition of 0.25 wt.% MWCNTs increases the compressive strength and elastic modulus of 45S5 Bioglass scaffolds from 2.08 to 4.56 MPa (a 119% increase) and 111.50 to 266.59 MPa (a 139% increase), respectively.

Figure 1

A schematic of freeze casting technique for the fabrication of the MWCNT/45S5 Bioglass scaffolds.

Figure 2

An optical image of the fabricated 0.5 wt.% MWCNT/45S5 Bioglass composite scaffolds before and after heat treatment at 900°C, which shows the shrinkage of samples.

Figure 3

(a) XRD spectra of the synthesized MWCNTs, (b) SEM micrograph of the synthesized MWCNTs, and (c) XRD spectra of the sol-gel derived 45S5 Bioglass after sintering at 1000°C for 2 h.

Figure 4

(a) Compressive strength and (b) elastic modulus of MWCNTs/45S5 Bioglass composite scaffolds as a function of MWCNTs content.

Figure 5

(a) Low magnification and (b) high magnification SEM micrographs of the agglomerated MWCNTs in the scaffolds with 0.5 wt.% MWCNTs.

Figure 6

SEM micrograph of microstructure of MWCNTs/45S5 Bioglass composite scaffold with 63% porosity. (a) Cross sections parallel to the ice front, (b) with more details.

Figure 7

SEM micrograph of an open pore in MWCNTs/45S5 Bioglass composite scaffold.

Figure 8

(a) Low magnification and (b) high magnification SEM micrographs of homogeneous distribution of MWCNTs in the 45S5 Bioglass matrix.

Figure 9

(a) Low magnification and (b) high magnification SEM micrographs of the bridges of CNTs between composite plates of the MWCNTs/45S5 Bioglass composite scaffold porosities (placing and crystallization of Bioglass particles on the CNT bridges).