Figure 1.
(a) FESEM micrograph of wrinkled top surface of GNPs, (b) TEM of GNPs/CS powder mixture showing the CS particles are well-dispersed throughout the surface area of the graphene sheets.
Figure 2.
XRD results of pure CS and GNP/CS composites sintered at 1150°C by HIP.
Figure 3.
Raman spectra of pristine GNP, GNP/CS composite (1 wt.% GNP) before HIP and GNP/CS composite (1 wt.% GNP) after HIP.
Table 1.
Peak position of the D and G bands and intensity ratios of ID/IG and I2D/IG.
Figure 4.
The effect of the GNP on the grain size and densification.
(a) Grain Size vs. GNP content. (b) Densification (relative to theoretical density) vs. GNP content.
Figure 5.
FESEM images of thermally etched surfaces for pure CS and GNP/CS composites.
Figure 6.
GNP toughening mechanisms in CS.
(a) Micro hardness indent resulting in the creation of radial cracks (inset image). Closer examination of the radial cracks revealed GNP bridging, (b) sheet pull-out, (c) crack branching, (d) crack deflection.
Table 2.
Mechanical properties of pure CS and GNP/CS composites.
Figure 7.
XRD patterns of pure CS and GNP/CS composites after soaking in the SBF solution for 14 days.
Figure 8.
Low and high magnification FESEM images of apatite formation on pure CS and GNP/CS composites after soaking in the SBF for 14 days.
Figure 9.
The change of pH value in SBF solution after soaking for various time periods.
Figure 10.
FESEM observations on cell morphology of hFOB osteoblasts cultured on pure CS and different GNP/CS composites after 24 hours.
The scale bar in all the images is 50 µm.
Figure 11.
Comparison of the cell adhesion and proliferation on pure CS and 1 wt.%GNP/CS composite surfaces at different time points:
(a) blank of pure CS, (b-d) 1, 3 and 5 days on pure CS discs, (e) blank of 1 wt.%GNP/CS, (f-h) 1, 3 and 5 days on 1 wt.%GNP/CS composite. The scale bar represents 50 µm.
Figure 12.
FESEM micrographs and the EDS spectrum of the hFOB cells.
(a) 1 wt.%GNP/CS composite without cells, (b) Pure CS with hFOB cells,(c) FESEM micrographs and the EDS spectrum of the hFOB cells, indicating a significant presence of P and CS on the 1 wt.%GNP/CS composite following 3 days of seeding.
Figure 13.
Proliferation of hFOB osteoblasts on different GNP/CS composites in comparison with pure CS and blank assessed using MTT assay (p<0.05,n = 5).