# Conclusion

Alginate-based scaffolds have been extensively investigated for NTE, however, they faced some limitations that hampered their further developments. Importantly, alginate-based scaffolds have poor mechanical strength and degradation rate, which are not matched with native tissue microenvironment. It was found that incorporation of graphene within the alginate matrix can address these drawbacks. However, it is important to investigate cellular viability and cytotoxicity of 3D graphene-based composite scaffold. In addition, it is revealed that coating of scaffolds induces cell functions, adhesion and growth. Therefore, this study examined the biodegradation, biocompatibility, bioactivity and cytotoxicity of neural crest-derived DPSCs loaded graphene-based 3D composite scaffolds, using three different coating conditions.
It was shown that the composite GOSA and RGOSA scaffolds have controlled biodegradability which is effective in therapeutic tissue engineering applications. DPSCs viability cultured onto SA and GOSA scaffolds was higher than that of on 2D controls thus signifying surface cell adhesion followed by cell infiltration through the porous matrices. Therefore, superior proliferative ability of DPSCs can be obtained when cells are cultured on 3D porous scaffolds. The LDH assay showed comparable DPSCs toxicity on the GOSA and RGOSA scaffolds to that obtained on a 2D surface in the absence of the biomaterial, highlighting no significant cytotoxic effects of graphene incorporation after 2 days of DPSCs culture. Furthermore, smaller mean pore size of scaffolds resulted in higher cellular activity and relatively less cytotoxicity, which is due to more available specific surface area on scaffolds with smaller mean pore sizes. In terms of coating conditions, PLL was the most robust reagent that improved cell-matrix adherence and affected metabolism activity of DPSCs, being superior to combined PLL+LAM coating. Furthermore, the cytotoxicity of GOSA and RGOSA scaffolds in the presence of serum is increased compared to serum-free condition, indicating that DPSCs can be cultured in serum deprivation onto the fabricated scaffolds for clinical translation. The findings from the current study suggest that the proposed 3D graphene-based composite scaffolds had a favourable effect on the biological responses of DPSCs which could be exploited in further DPSCs differentiation and electrical stimulation for functional NTE.