Biological Evaluation of Graphene Quantum Dots and Nitrogen-Doped Graphene Quantum Dots as Neurotrophic Agents

Abstract

Over time, developments in nano-biomedical research have led to the creation of a number of systems to cure serious illnesses. Tandem use of nano-theragnostics such as diagnostic and therapeutic approaches tailored to the individual disease treatment is crucial for further development in the field of biomedical advancements. Graphene has garnered attention in the recent times as a potential nanomaterial for tissue engineering and regenerative medicines owing to its biocompatibility among the several other unique properties it possesses. The zero-dimensional graphene quantum dots (GQDs) and their nitrogen-doped variant, nitrogen-doped GQDs (N-GQDs), have good biocompatibility, and optical and physicochemical properties. GQDs have been extensively researched owing to several factors such as their size, surface charge, and interactions with other molecules found in biological media. This work briefly elucidates the potential of electroactive GQDs as well as N-GQDs as neurotrophic agents. In vitro investigations employing the N2A cell line were used to evaluate the effectiveness of GQDs and N-GQDs as neurotrophic agents, wherein basic investigations such as SRB assay and neurite outgrowth assay were performed. The results inferred from immunohistochemistry followed by confocal imaging studies as well as quantitative real-time PCR (qPCR) studies corroborated those obtained from neurite outgrowth assay. We have also conducted a preliminary investigation of the pattern of gene expression for neurotrophic and gliotrophic growth factors using ex vivo neuronal and mixed glial cultures taken from the brains of postnatal day 2 mice pups. Overall, the studies indicated that GQDs and N-GQDs hold prospect as a framework for further development of neuroactive compounds for relevant central nervous system (CNS) purposes.

Potential of Zinc Oxide-Graphene Quantum Dots and Zinc Oxide-Nitrogen-Doped Graphene Quantum Dot Nanocomposites as Neurotrophic Agents

“…Required chemicals were procured from Sigma-Aldrich, Finar chemicals, and Genetix Biotech Asia Pvt. Ltd. and Spectrum Laboratories, Inc. and were employed without subjecting them to any other purification processes, as described in our previous works. ,, Distilled water (DW) and Milli-Q water (resistance 18.2 MΩ cm –1 , TOC of 10 ppb) were used throughout the experiment.…”

“…GQDs and N-GQDs were prepared according to our previously reported procedure. , To prepare the nanocomposite, a calculated amount of ZnO NPs were dispersed in solutions containing different wt %'s of GQDs and N-GQDs, labeled as ZG1-X and ZG2-X wherein X = a , b , c ( a = 0.5 wt %, b = 1 wt %, and c = 2 wt %) and stirred overnight. Centrifugation of the above dispersions was carried out to remove the impurities, and the samples were oven-dried to get the respective nanocomposites.…”

“…DLS measurements were carried out using an Anton Paar Litesizer 500. Electrochemical studies were performed under similar conditions with serum-deprived media as the electrolyte as described in our recent work …”

“…For the treatment, compounds were diluted in PBS to achieve the various concentrations needed for this investigation. The SRB assay protocol was followed as described earlier . Briefly, the cytotoxicity studies were performed against the Neuro2A cell line using three different concentrations (1, 5, and 10 μg mL –1 ) of pristine Z nanoparticles and ZG1-X and ZG2-X nanocomposites after 24 h of treatment with samples.…”

“…The potential of GQDs and N-GQDs as neurotrophic agents was first reported by our research group, despite the fact that the toxicity of GQDs has been well investigated. This study paved the way for the emergence of drugs for CNS treatment …”