The Emerging Applications of Graphene Oxide and Graphene in Tissue Engineering - Biomimetics: Advancing Nanobiomaterials and Tissue Engineering - page 283

GO substrate itself has been shown to exert a signifi cant infl uence on
various cell behaviors, such as cell adhesion, proliferation, and differentia-
tion, likely due to its aromatic structure, which can adsorb natural ECM
components, such as fi bronectin, laminin, and collagen, through nonco-
valent interactions [4]. According to our recent study, the degree of reduc-
tion of GO appears to be a crucial parameter controlling the production
of biocompatible and functional GO fi lms [64]. Here, GO fi lms were ther-
mally reduced at different reduction times. Glass slide substrate was also
used as the control sample. Results revealed that moderately reduced GO
fi lms for 90 min had the best biological performance as measured by the
cell adhesion, proliferation, and differentiation of various cell types, i.e.,
fi broblast, osteoblast, and muscle myoblast cells [64]. The latter substrate
had the highest amount of protein adsorption among fi lms. Another study
revealed that osteoblasts showed favorable attachment, viability, and
growth on hybrid silicone-GO substrates compared to the neat silicone
substrates [65]. The latter effects were attributed to the physico-chemical
properties (i.e., hydrophilicity and topography) of the composite sub-
strates due to the presence of the GO component [65].

12.4 Graphene and Its Cell and TE Applications

An early study showed that sheet-like graphene is a biocompatible mate-
rial as assessed using mouse fi broblast cells (L-929) [66]. Interestingly, the
cell proliferation rate for the graphene sheet and the conventional tissue
culture dish was almost similar. Biocompatibility is an essential prerequi-
site for a material to be considered for biomedical applications. Here, gra-
phene solution was prepared so as to reduce the GO with hydrazine. The
sheet-like graphene was then fabricated by the fi ltration of graphene solu-
tion through a membrane, followed by air drying and removal from the
fi lter. Recently, Ryoo et al. showed that NIH-3T3 fi broblasts could adhere,
spread, and grow well on graphene substrates, as demonstrated by the
cell proliferation assay, focal adhesion assessment, cell shape analysis, and
gene expression analysis of cell adhesion-related genes (i.e., integrin, col-
lagen types I and III, a -actin, and focal adhesion kinase) [67]. Interestingly,
the gene transfection effi ciency of the fi broblast cells grown on the gra-
phene substrates increased to 250% of that of the cells cultured on the
conventional cover glasses. Therefore, the graphene substrates can be
used for an effi cient gene transfection of cells while the cell density is lim-
ited. The graphene substrates promoted the neural growth and neurite
sprouting of mouse hippocampal cells to a greater degree than the con-
ventional tissue culture polystyrene substrates [68]. Neurites are defi ned
as any projections from the neuron cell body, such as axons or dendrites.
Graphene-cell interactions were studied using Western blot analysis,