Facile fabricating of rGO and Au/rGO nanocomposites using Brassica oleracea var. gongylodes biomass for non-invasive approach in cancer therapy

Abstract

In this study, we report a facile green-synthesis route for the fabrication of reduced graphene oxide (rGO) using biomass of Brassica oleracea var. gongylodes (B. oleracea). In addition, we have attempted to provide a green synthesis approach to prepare Gold nanoparticles (Au NPs) on the surface of rGO by using stem extract of B. oleracea. The synthesized Au/rGO nanocomposite was evaluated using UV-visible and FTIR spectroscopy, XRD, Raman, FE-SEM, EDX, AFM and DLS techniques. The obtained results demonstrated that the synthesized Au NPs on the surface of rGO was spherical with sizes ranging about 12-18 nm. The Au/rGO NC was, also, developed as photo-synthesizer system for the photothermal therapy (PTT) of MCF7 breast cancer cells. The near-infrared (NIR) photothermal properties of Au/rGO NCs was evaluated using a continuous laser at 808 nm with power densities of 1 W.cm^-2. Their photothermal efficacy on MCF7 breast cancer cells after optimizing the proper concentration of the NCs were evaluated by MTT assay, Cell cycle and DAPI staining. In addition, the potential of the synthesized Au/rGO NCs on reactive oxygen species generating and antioxidant activity were assessed by DPPH. Au/rGO NCs possess high capacity to light-to-heat conversion for absorption in range NIR light, and it is able to therapeutic effects on MCF7 cells at a low concentration. The maximum amount of cell death is 40.12% which was observed in treatment groups that received a combination of Au/rGO NCs and laser irradiation. The results demonstrate that the nanomaterials synthesized by green approach lead to efficient destruction of cancer cell and might thus serve as an excellent theranostic agent in Photothermal therapy applications.

Figure 1

(a) UV–Vis spectra of rGO and rGO/Au NCs; (b) FTIR spectra of rGO and rGO/Au NCs.

Figure 2

The possible mechanism for formation of rGO/Au NCs.

Figure 3

(a) XRD patterns of rGO and Au/rGO NCs; (b) Raman spectra of prepared rGO, Au/rGO NCs.

Figure 4

FE-SEM images of rGO (a, b), Au/rGO NCs and EDS pattern of Au/rGO NCs in insets of thumbnail (c, d); AFM image of rGO (e, f); DLS of the rGO (g) and Au/rGO NCs (h).

Figure 5

Radical scavenging activity and ROS generation of the Au/rGO NCs.

Figure 6

(a) Cell viability results of the MCF7 cells treated with Au/rGO NCs; (b) Cell viability of the MCF7 cells in presence and absence Au/rGO NCs and exposure NIR irradiation for 6 and 10 min.

Figure 7

(a) Microscopic images of DAPI stained MCF7 cells after exposure by NIR laser irradiation for 10 min , untreated MCF7 cells (negative control), Au/rGO NCs and Au/rGO NCs + laser; (b) Cellular uptake of MCF7 cells lines treated with Rhodamine B-labelled Au/rGO NCs for exposure durations of 0.5, 1.5 and 3 h captured by florescent microscopy.

Figure 8

Cell cycle arrest quantitative results obtained by flow cytometry, negative control (untreated cells) (a), cells treated by Au/rGO NCs (b), cells irradiated for 6 min (c) 10 min (d) (positive control), cells treated by Au/rGO NCs irradiated for 6 min (e) and 10 min (f).