Abstract
ObjectiveGraphene has been widely used for various biological and biomedical applications due to its unique physiochemical properties. This study aimed to evaluate the cardiotoxicity of graphene oxide (GO) and reduced GO (rGO) in vitro and in vivo, as well as to investigate the underlying toxicity mechanisms.MethodsGO was reduced by gamma irradiation to prepare rGO and then characterized by UV/visible light absorption spectroscopy. Rat myocardial cells (H9C2) were exposed to GO or rGO with different absorbed radiation doses. The in vitro cytotoxicity was evaluated by MTT assay, cell apoptosis assay, and lactate dehydrogenase (LDH) activity assay. The effects of GO and rGO on oxidative damage and mitochondrial membrane potential were also explored in H9C2 cells. For in vivo experiments, mice were injected with GO or rGO. The histopathological changes of heart tissues, as well as myocardial enzyme activity and lipid peroxidation indicators in heart tissues were further investigated.ResultsrGO was developed from GO following different doses of gamma irradiation. In vitro experiments in H9C2 cells showed that compared with control cells, both GO and rGO treatment inhibited cell viability, promoted cell apoptosis, and elevated the LDH release. With the increasing radiation absorbed dose, the cytotoxicity of rGO gradually increased. Notably, GO or rGO treatment increased the content of ROS and reduced the mitochondrial membrane potential in H9C2 cells. In vivo experiments also revealed that GO or rGO treatment damaged the myocardial tissues and changed the activities of several myocardial enzymes and the lipid peroxidation indicators in the myocardial tissues.ConclusionGO exhibited a lower cardiotoxicity than rGO due to the structure difference, and the cardiotoxicity of GO and rGO might be mediated by lipid peroxidation, oxidative stress, and mitochondrial dysfunction.
Highlights
In recent years, nanomaterials have been reported to be promising functional materials and display great application potentials in various fields, such as materials, communication, energy, and biomedicine (Guozhong, 2004)
Optical absorption spectra revealed that the wavelength of graphene oxide (GO) was increased with the increasing radiation absorbed dose (Figure 1D), which suggested that GO was reduced by gamma irradiation as reduced GO (rGO)
MTT assay showed that compared with control cells, GO or rGO obtained with increasing radiation-absorbed doses inhibited cell viability at 24 and 48 h (Figure 2B)
Summary
Nanomaterials have been reported to be promising functional materials and display great application potentials in various fields, such as materials, communication, energy, and biomedicine (Guozhong, 2004). As a “wonder material,” graphene is composed of singlelayer sheet-like and two-dimensional carbon atoms with sp hybridized hexagonal honeycomb structure (Choi and Lee, 2016) It has been applied in biomedical fields, including drug delivery (Yang et al, 2015), cellular imaging (You et al, 2015), solid/liquid phase microextraction (Rezaeifar et al, 2016), and cancer therapy (Rahman et al, 2015; Krasteva et al, 2019). A variety of graphene-derived nanomaterials (GFNs), such as graphene oxide (GO) and reduced GO (rGO), have attracted a lot of interest in biomedical applications due to their exceptional physical and chemical properties, including good thermal stability, excellent mechanical strength, and high electronic conductivity (Zhang et al, 2016; Papageorgiou et al, 2017). The difference of GO and rGO in the content of oxygen-containing groups results in different surface properties, such as surface charge, electrical conductivity, and hydrophobicity (Chatterjee et al, 2014)
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