Elsevier

Materials Letters

Volume 183, 15 November 2016, Pages 127-130
Materials Letters

Tithonia diversifolia pectin – reduced graphene oxide and its cytotoxic activity

https://doi.org/10.1016/j.matlet.2016.07.088Get rights and content

Highlights

  • Graphene oxide was reduced by pectin from Tithonia diversifolia.

  • The reduction of the graphene oxide was confirmed by various characterization methods.

  • Cytotoxicity of GO and TDP-rGO to RD and LU-1 cells was evaluated

Abstract

Reduced graphene oxide was one-pot synthesized from graphene oxide using pectin from Tithonia diversifolia as a reducing and stabilizing agent. The success of the process was confirmed by UV–vis, FT-IR, XRD spectroscopy. The TEM and AFM images showed the structure of few-layer graphene nanosheets with the dimension of hundreds nm and the thickness about 2.5 nm. The cytotoxic tests revealed that the reduction process of graphene oxide using pectin led to a lower cytotoxicity.

Introduction

Graphene has become a hot research topic with great potential in various applications such as electronic [1], [2], energy storage [3], nanocatalyst [4]. However, due to their hydrophobicity and toxicity, the development of graphene and graphene oxide (GO) in biomedicine including drug delivery, cancer and phototherapy has been not as high as in the other applications [5]. In fact, many works reported that the Van der Waals interactions and the strong π–π stacking between graphene nanosheets (GNS) made them tend to aggregate and restack back to graphite [6]. Besides, GO exhibits potential cytotoxicity due to its flat structure with the sharp edge which may cause the membrane cell damages [7]. Therefore, functionalization chemistry is one of the most efficient solutions to improve the aqueous solubility and biocompatibility of graphene and GO [6], [8], [9]. Recently, it was found that several green functionalization agents such as green tea polyphenol [10], starch [11], curcumin [12] could make lower cytotoxic effects as well as better aqueous solubility.

Among natural products, pectin – also known as pectic polysaccharides in cell walls of plants which extensively use in food and pharmaceutical industry – has been reported as an efficient and biocompatible reductant in nanomaterials production [13], [14]. The most desirable property of pectin is gastric resistance and degradable by colonic bacteria, which makes it suitable for oral drug delivery systems [15]. Tithonia diversifolia, (Hemsley) A. Gray, a traditional medicinal plant belonging to Asteraceae family, is known as an abundant source of pectin.

This work presents a green method to produce reduced graphene oxide (TDP-rGO) using pectin from T. diversifolia which is suitable for broad biomedical applications. The cytotoxic assays of pectin, GO and TPD-rGO were evaluated against human rhabdomyosarcoma (RD) and human lung cancer (LU-1) cell lines.

Section snippets

Materials and methods

Graphite, potassium permanganate, sulfuric acid, hydrogen peroxide, ethanol, and hydrochloric acid (Sigma-Aldrich) were used directly without further purification.

The powder of T. diversifolia (100 g) was percolated with 3 L of ethanol for 2 weeks then extracted with deionized water (2 L) at 100 °C for 30 min (3 times). All aqueous extracts were combined and concentrated. After deproteinization with Sevag reagent [16], aqueous fraction was dialyzed against deionized water and precipitated with

Results and discussion

UV–vis spectroscopy is a simple and useful tool to confirm the reduction process of GO. Additionally, the observation of color change from light brown to black also supported for the study. The obtained dispersion of TDP-rGO has been stable for months without any aggregations. As shown in Fig. 1(a), the π→π* transition peak for C˭C of GO revealed at ∼230 nm while the additional peak at 300 nm was ascribed to the n→π* transition of C˭O, confirming the presence of oxygen-containing functional

Conclusions

A green approach using pectin from T. diversifolia for reduced graphene oxide production is reported. The process produced a stable dispersion of few-layer graphene nanosheets with the thickness about of 2.5 nm. The cytotoxic testing results show that pectin from T. diversifolia could help reduce the toxicity of obtained GNS which makes them suitable for many biological applications.

Acknowledgements

This research is funded by Vietnam National Foundation for Science and Technology Development (NAFOSTED) under grant number 106-NN.02-2013.49.

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