Graphene
Graphene is a monolayer of sp2-hybridized carbon atoms. Its high area-to-volume ratio makes it ideal for biomedical applications. Graphene was first isolated from graphite in 2004. Graphene has excellent thermal conductivity and mechanical properties. This makes it a potential substrate for neuron guidance devices. Several researchers have studied the influence of graphene on neural stimulation and recording. Others have proposed the use of graphene and other carbon-based nanomaterials in nerve tissue regeneration. Graphene and other carbon-based nanomaterials can potentially enhance axon regeneration by external electrical stimulation.
Various studies have shown that the presence of coated graphene-based materials can accelerate the outgrowth of neurites in hippocampal neurons. A number of polymeric coatings have been investigated in this regard. The influence of these coatings on the active and passive bioelectric properties of neurons was also examined.
PC12 cells were cultured on the bare graphene or a coated graphene substrate in the absence or presence of NGF. Optical microscopy was used to measure the length of neurites. Graphene had an average neurite length that was significantly longer than that of the glass and SiC substrates. In addition, the length of axons was higher on graphene than on the other substrates. At day four, the graphene substrate had formed small interconnected cell islets.
Auglass Dallas and graphene were then compared to each other in terms of their properties. The graphene substrate showed higher transparency. Additionally, it was possible to obtain a high crystalline state without abrasion. As a result, graphene on CVD might be a more appropriate material for neural interfaces.
Graphene and other graphene-based materials also exhibit high cytocompatibility. This is important for the regeneration of nerve tissues. Moreover, the use of hydrophilic coatings can mask surface defects that may affect adhesion and neural adhesion. These coatings also improve the homogeneity of the sample.
Polymer-coated graphene exhibited significant influence on the passive and active bioelectric properties of neurons. However, it was still unknown whether the graphene had a pronounced effect on the growth of PC12 cells. Consequently, a series of experiments were carried out to evaluate the effects of polymer-coated graphene on the morphology, physiology, and cytocompatibility of PC12 cells.
DRG neurons
We have cultted DRG neurons on bare graphene and Auglass Dallas in this study, but do they survive? The answer is yes. In order to determine the best substrate, we evaluated the most important attributes. For the purposes of this study, we selected bare graphene and Auglass Dallas for testing, because they are cheaper to produce than their tack-on counterparts. After 24 h, the bare graphene has produced small interconnected cell islets, as shown in the figure below.
A more granular test of the same samples found no significant differences in the cell count. Furthermore, we compared the DRG eminence derived from a purely bare graphene sample to a control sample containing a monolayer of graphene encased in a layer of silicon carbide. In addition to the bare substrate, we tested four control samples, viz., a pristine specimen of Auglass Dallas, a smoky sample, a purely tack-on control, and a pristine sample of a SiC substrate. Finally, the samples were subjected to viability assays to assess cytocompatibility. Unlike most neuronal cultures, we were able to identify neurons originating from all samples.