Green tea polyphenol-reduced graphene oxide: derivatisation, reduction efficiency, reduction mechanism and cytotoxicity

Abdullah, M. F.; Zakaria, R.; Zein, S. H. S.

Abstract

This paper reports on the derivatisation, reduction efficiency, reduction mechanism and cytotoxicity of green tea polyphenol-reduced graphene oxide (GTP-RGO). The reduction of graphene oxide (GO) at 90°C using a weight ratio (WR) of GTP/GO=1 resulted in the production of a stable GTP-RGO dispersion in aqueous media, as indicated by the results of ultravioletvisible (UV-Vis) spectroscopy, Fourier transform infrared (FTIR) spectroscopy, thermogravimetric analysis (TGA) and the measurement of zeta potential and electrophoretic mobility. In addition, the results from UV-Vis spectroscopy and X-ray photoelectron spectroscopy (XPS) analysis indicated the comparable reduction ability of GTP relative to the standard reducing agent, hydrazine (N2H4). The removal mechanism of epoxy group from GO via reduction reaction with GTP was investigated by implementing hybrid functional method of Becke-3-parameters-Lee-Yang-Parr (B3LYP)using Gaussian 09 software. The energy and frequency calculations showed that the GO reduction using GTP was more spontaneous and relatively took place faster than the reduction using N2H4, as evidenced by higher entropy change (ΔS) (0.039 kcal/mol·K) and lower Gibbs free energy (ΔG) barrier (58.880 kcal/mol).The cytotoxicities of GO and GTP-RGO samples were evaluated against human colonic fibroblasts cells (CCD-18Co). The GO sample was determined to be toxic even at low concentration (6.25 μg/mL), while the GTP-RGO sample possesses notably low toxicity at the same concentration. The cell culture experiments revealed that the incorporation of GTP led to a decrease in the toxicity of GTP-RGO samples.

Citation

Abdullah, M. F., Zakaria, R., & Zein, S. H. S. (2014). Green tea polyphenol-reduced graphene oxide: derivatisation, reduction efficiency, reduction mechanism and cytotoxicity. RSC advances, 4(65), 34510-34518. https://doi.org/10.1039/c4ra04292a

• Acceptance Date: Jul 30, 2014
• Online Publication Date: Jul 30, 2014
• Publication Date: Jul 30, 2014
• Deposit Date: Jun 16, 2016
• Publicly Available Date: Jun 16, 2016
• Journal: RSC advances
• Print ISSN: 2046-2069
• Electronic ISSN: 2046-2069
• Publisher: Royal Society of Chemistry
• Peer Reviewed: Peer Reviewed
• Volume: 4
• Issue: 65
• Pages: 34510-34518
• DOI: https://doi.org/10.1039/c4ra04292a
• Keywords: Graphene oxide; Reduced graphene oxide; Green tea polyphenol; Reduction mechanism; Cytoxicity
• Public URL: https://hull-repository.worktribe.com/output/439735
• Publisher URL: http://pubs.rsc.org/en/content/articlelanding/2014/ra/c4ra04292a#!divAbstract
• Additional Information: This is the authors accepted manuscript of an article published in RSC advances, 2014, v.4.
• Contract Date: Jun 16, 2016