Facile green reduction of graphene oxide using Ocimum sanctum hydroalcoholic extract and evaluation of its cellular toxicity

• Published in: Materials chemistry and physics 2017-09, Vol.198, p.66-72
• Main Authors: Shubha, P., Namratha, K., Aparna, H.S., Ashok, N.R., Mustak, M.S., Chatterjee, Jit, Byrappa, K.
• Format: Article
• Language: English
• Subjects: Antioxidants; Assaying; Biocompatibility; Biosensors; Carbon; Cells; Curtains; Drug delivery systems; Efflux; Fibroblasts; Flavonoid; Flavonoids; Free radicals; Graphene; Haemolysis; Hemoglobin; In vivo methods and tests; Ocimum sanctum; Phenolics; Phenols; Reduction; Refluxing; Toxicity; Toxicology; Viability
• ISSN: 0254-0584; 1879-3312
• DOI: 10.1016/j.matchemphys.2017.05.062

Currently, biological application of graphene family materials is widely explored from drug delivery to biosensing. In this study, we reduced graphene oxide (GO) using hydroalcoholic extract of Ocimum sanctum (holy basil) by refluxing with 5% extract solution. Total phenols and flavonoids present in extract were assayed using appropriate methods as these phytocompounds are known to influence reducing capacity. 2, 2-diphenyl 1- picrylhydrazyl (DPPH) assay and IC 50 value determination was carried out to know the potency of plant extract as antioxidant. Total phenolic content in hydroalcoholic extract of O sanctum was found to be 20% and total flavonoid content was found to be 7.5%. DPPH assay showed ∼90% inhibition of free radicals by extract at 10 μg/mL concentration and ∼42% inhibition at 0.75 μg/mL and IC 50 value of 1.3 μg/mL showing that the extract is a potential antioxidant. Characterization of GO and O sanctum reduced GO (ORGO) showed that PXRD of ORGO had a broad peak centred at 2θ = 25° as against 2θ = 10.69° of GO indicating efficient removal of oxygen containing group. SEM images of GO showed typical flake like morphology whereas ORGO appeared like overlapped folded curtains, typical of their respective morphologies. To assay the concentration dependent toxicology profile of GO and ORGO, efflux of haemoglobin from suspended red blood corpuscles was estimated spectroscopically at 541 nm. Viability of mouse fibroblast cells (Balb 3T3 cells) under the influence of different concentrations of GO/ORGO was examined with water soluble tetrazolium salt using cell counting kit assay (CCK-8). GO here showed higher haemolytic activity of 6.9% and higher inhibition of growth of 3T3 cells at all tested concentrations than ORGO, which is probably due to removal of oxygen functionalities by plant extract in the latter. From this study, we conclude that O sanctum hydroalcoholic extract has been efficiently employed as a reductant in removal of functionalities of GO and thus synthesized ORGO showed lesser hematologic and cellular toxicity and the material can be a good entrant for biological applications after further in vivo studies. •Ocimum sanctum, an easily cultivable medicinal herb is used as reducing agent.•The herbal extract demonstrated good phenolics and flavonoid content.•Extract had potent antioxidant activity and IC 50 value comparable to ascorbic acid.•Extract caused excellent reduction of GO, confirmed with characterization of ORGO.•ORGO was biocom