Abstract
Graphene-based materials have an opportunity for use in biomedicine, thanks to their properties. Nevertheless, due to its cytotoxic effects, the use of graphene-based drugs is problematic. However, the surface modification of graphene oxide (GO) nanoparticles with a polyethyleneglycol (PEG) is one way to reduce the harmful effects of graphene on cells. Applying nanoparticles implies their interaction with the immune system, which protects the body. Monocytes are innate immunity cells and the first line of defenсe of the human organism from microorganisms and other alien objects. One of the monocytes’ reactions to a stimulus of any nature is to produce reactive oxygen species (ROS). Published data shows an incomplete picture of modified graphene oxide nanoparticles’ effects on ROS formation by human monocytes. Thus, it was essential to evaluate the pegylated graphene oxide (GO-PEG and GO-8armedPEG) effect on ROS production by human monocytes, assessed by the luminol-dependent chemiluminescence (LCL). The objects of the study were CD14+-cells isolated from mononuclear cells of healthy donors. ROS production was stimulated by opsonized zymosan (OZ), spontaneous LCL was used as a control. PEG-modified (GO-PEG and GO-8armedPEG) GO nanoparticles with sizes of 100-200 nm (“small”) and 1-5 μm (“big”) with PEG covering ~ 20% were used at concentrations of 5 and 25 μg/ml. The study showed that small size nanoparticles at a low concentration of 5 μg/ml and big nanoparticles coated with 8-armed PEG at both concentrations have a significant suppressive effect on spontaneous ROS production. In the stimulated LCL reaction variant, it was found that small nanoparticles (25 μg/ml) also have a suppressive effect on ROS production, such as big-sized particles coated with linear PEG at the same concentration. Thus, we have established for the first time that graphene oxide nanoparticles functionalized with PEG are capable of inhibiting the ROS production by human monocytes, and therefore, we can speak of the antioxidant activity of GO-PEG.
Highlights
Graphene is a lightweight two-dimensional ma terial made from a monatomic carbon layer
The resulting suspensions of graphene oxide (GO)-polyethylene glycol (PEG) or GO-8armPEG were purified by dialysis and triple washing by centrifugation with ethyl alcohol with final drying at 65 °С under vacuum
Cell stimulation is accompanied by the superoxide anion, hydrogen peroxide, hydroxyl radical, and chlorine active form generation, which have a potent bacte ricidal effect; and the luminol-dependent chemiluminescence (LCL) reaction characterizes the total reactive oxygen species (ROS) production by isolated monocytes
Summary
Graphene is a lightweight two-dimensional ma terial made from a monatomic carbon layer. It is known that the surface modification (functionalization) of GO nanoparticles using the polymer-adsorbed particles is one of the ways to reduce the harmful graphene-related cell effects [2, 3]. Our work aimed to study PEG-modified GO nanoparticle effect on the oxidative activity of human monocytes, assessed by luminol-dependent chemiluminescence (LCL).
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