Quercetin-mediated synthesis of graphene oxide–silver nanoparticle nanocomposites: a suitable alternative nanotherapy for neuroblastoma

Abstract

Background Graphene and graphene-related materials have gained substantial interest from both academia and industry for the development of unique nanomaterials for biomedical applications. Graphene oxide (GO) and silver nanoparticles (AgNPs) are a valuable platform for the development of nanocomposites, permitting the combination of nanomaterials with different physical and chemical properties to generate novel materials with improved and effective functionalities in a single platform. Therefore, this study was conducted to synthesize a graphene oxide–silver nanoparticle (GO-AgNPs) nanocomposite using the biomolecule quercetin and evaluate the potential cytotoxicity and mechanism of GO-AgNPs in human neuroblastoma cancer cells (SH-SY5Y). Methods The synthesized GO-AgNPs were characterized using various analytical techniques. The potential toxicities of GO-AgNPs were evaluated using a series of biochemical and cellular assays. The expression of apoptotic and anti-apoptotic genes was measured by quantitative real-time reverse transcription polymerase chain reaction. Further, apoptosis was confirmed by caspase-9/3 activity and a terminal deoxynucleotidyl transferase dUTP nick end labeling assay, and GO-AgNPs-induced autophagy was also confirmed by transmission electron microscopy. Results The prepared GO-AgNPs exhibited significantly higher cytotoxicity toward SH-SY5Y cells than GO. GO-AgNPs induced significant cytotoxicity in SH-SY5Y cells by the loss of cell viability, inhibition of cell proliferation, increased leakage of lactate dehydrogenase, decreased level of mitochondrial membrane potential, reduced numbers of mitochondria, enhanced level of reactive oxygen species generation, increased expression of pro-apoptotic genes, and decreased expression of anti-apoptotic genes. GO-AgNPs induced caspase-9/3-dependent apoptosis via DNA fragmentation. Finally, GO-AgNPs induced accumulation of autophagosomes and autophagic vacuoles. Conclusion In this study, we developed an environmentally friendly, facile, dependable, and simple method for the synthesis of GO-AgNPs nanocomposites using quercetin. The synthesized GO-AgNPs exhibited enhanced cytotoxicity compared with that of GO at very low concentrations. This study not only elucidates the potential cytotoxicity against neuroblastoma cancer cells, but also reveals the molecular mechanism of toxicity.

Cytotoxic Potential and Molecular Pathway Analysis of Silver Nanoparticles in Human Colon Cancer Cells HCT116

“…These results indicate that high concentrations of AgNPs damage cellular membrane integrity. Our results agree with those of previous reports showing that AgNPs induce leakage of LDH in different type of cancer cells and non-cancer cells, including human breast cancer cells [14,38], human lung cancer cells [17], human ovarian cancer cells [16], human neuroblastoma cells [39], human microvascular endothelial cells [42], male somatic cells, spermatogonial stem cells [8], and neural stem cells [43]. Collectively, the results suggest that reduced viability was observed in HCT116 cells exposed to AgNPs, which correlates with the increased leakage of LDH and significantly strong cytotoxicity.…”

Graphene oxide-silver nanocomposites induce oxidative stress and apoptosis in caprine fetal fibroblast cells

“…Compared to pristine AgNPs, GO-AgNPs signi cantly induced generation of ROS in the macrophage in a dose-dependent manner [48]. In current study, the level of ROS increased signi cantly at a 1.4-and 1.8-fold in caprine fetal broblast cells after treatment with 4 and 8 µg/mL GO-AgNPs for 24 h. Our results are consistent with previous reports on various cancer cell lines with graphene and graphenerelated materials [30,42]. The up-regulated ROS level in caprine fetal broblast cells alters the mitochondrial functions and plays a key role in apoptosis induction, which proved by the data of Annexin V/PI double labeling assay and increasing level of caspase-3.…”

“…The present data showed that 20 nm GO-AgNPs reduced cell growth, viability and induced morphological changes in a concentration-dependent manner. In our previous study, GO-AgNPs signi cantly decreased the human ovarian cancer cell viability with an IC 50 of 5 µg/mL [42], which is lower than that in the present study, suggesting that caprine fetal broblast cells are less sensitive to GO-AgNPs than human cancer or mouse cells. AgNPs with different sizes and surface coatings or without coatings are likely to contribute to these different results.…”

“…One of the main mechanisms of toxicity induced by nanomaterial is that it causes oxidative stress through the generation of ROS and causes damage to cellular components including DNA damage, abnormal activation of transcription factors, depletion of antioxidant molecules, binding and disabling of proteins, and damage to the cell membrane [26]. Oxidative stress inducing ROS is one of the proposed toxicological mechanisms of various nanomaterials such as Ag or Ag-graphene nanocomposites, can cause mitochondrial damage, and initiation of lipid peroxidation [42,45,46]. Cytotoxicity of AgNPs is associated with increased production of ROS, which play an important role in apoptosis induced by AgNPs [47].…”

“…Assessing the release of intracellular LDH in cell, which resulted from the breakdown and alteration in the permeability of the plasma membrane, is one of marker for estimating cytotoxicity [30,46]. rGO-Ag increases LDH leakage in human cancer cells, thus resulting in cell death [30,42,52]. The present data indicated that the mechanism of increased level of MDA and LDH in GO-AgNPs-treated caprine fetal broblast cells may be due to the strong hydrophobic interactions with the cell membrane and ROS formation, which in uenced the viability and proliferation of cells, suggesting the possible cytotoxicity of GO-AgNPs on caprine fetal broblast cells.…”