The desire to create an idealised substrate for the growth of neural based cells has been a research ambition for many years. Neural based cells are notoriously difficult to culture, normally requiring the creation of a specially prepared substrate to allow for their attachment, growth and differentiation. Although polylysine serves as an adequate functional treatment for this purpose in vitro its associated cytotoxicity present difficulties for in vivo applications. Although progress has been made in recent years with regards to the initial development of brain computer interfaces (BCIs) and the bionic eye research in the field could be significantly accelerated through the development of novel successful neurocompatible substrates. It is envisaged that the utilisation of amine-functionalised nanodiamond or diamond-like carbon may fulfill this role due to the ability for diamond surfaces to be neurocompatible, mechanically strong, readily applied as a surface coating, highly stable and easily functionalised.
Additionally, there also exists demand for the creation of nanoparticles to act as bioimaging agents which possess the fluorescence capabilities of quantum dots without the associated cytotoxicity issues. Research progression has unveiled that carbon nanoparticles produced swiftly and in large quantities, from the pyrolysis of carbohydrates, may eclipse quantum dots due to their superior biocompatibility, excellent fluorescence emission levels, environmentally friendly synthesis methods and lack of photobleaching. This area of research is still rapidly expanding, with many carbonaceous compounds still awaiting investigation for their potential as creating carbon nanoparticles (CNP) favourable for bioimaging purposes. It is envisaged the key to creating successfully fluorescent CNPs which can be translocated within cells boils down to a number of factors, including surface functionality, CNP diameter, and carbon source.
One of the aims of this thesis was to investigate the suitability of amine-functionalised nanodiamond and diamond-like carbon derived substrates for the culture of neuronal cell lines and primary neural cells and also to investigate their effectiveness in comparison to conventional polylysine functionalised surfaces. These novel substrates were illustrated to support neural cells as effectively as conventional polylysine surfaces with cells displaying numerous neuritis of up to 300 µm in length. Furthermore, primary cells were supported on the functionalised substrates for up to three weeks without any indication of apoptosis or cell detachment and cell viability assays indicated no deviation in activity from cells cultured on functionalised and control samples.
In addition, a further aim was to identify the suitability of CNPs derived from multiple saccharide sources (i.e. glucose, sucrose and alginate) as potential bioimaging replacements for presently used quantum dots / fluorescent dyes which are unfortunately subject to photobleaching or cytotoxicity issues. Those CNPs derived purely from either glucose, sucrose or alginate were shown to have luminescence capabilities similar to conventional fluorescent tags, clearly allowing for the morphology of the cells tested to be recorded after cells were exposed to the CNPs for a 2 hour period. This luminescence was shown to still be visually detectable three years post CNP synthesis and the particles were shown to have no significant effect upon cell viability illustrating their widespread potential within scientific research.
