Graphene Quantum Dots for Radiotherapy

Abstract

Radiation therapy is a kind of tumor treatment that has been widely employed in clinics, but its therapeutic effect is largely hampered by various factors. Currently, considerable efforts are being made in the search for effective and safe radiosensitizers. A nano-radiosensitizer is an ideal choice for improving the effects of tumor radiotherapy due to its high degree of tumor tissue uptake and secondary electrons' productivity. Herein, highly oxidized graphene quantum dots (GQDs) with a good oxidative stress response and significantly high phototoxicity were prepared and purified via the photo-Fenton reaction of graphene oxide. The enhanced radiosensitization effects were systematically evaluated by monitoring colorectal carcinoma cell cycle and the degree of apoptosis, and the possible mechanism of the GQD irradiating enhancement of cell apoptosis was preliminarily investigated. Our data showed that the GQD synergy with ionizing radiation (IR) could noticeably enhance the G2/M stage arrest of cells, inhibit cell proliferation, and improve apoptosis. This is mainly due to the overproduction of reactive oxygen species by GQDs in combination with the IR, which activates the apoptosis-related regulation proteins and results in tumor cell apoptosis. This study suggests that the GQDs can act as a new nano-radiosensitizer in tumor radiotherapy.

Induction of ferroptosis in response to graphene quantum dots through mitochondrial oxidative stress in microglia

“…Apart from iron overburden evidenced by a specific fluorescent probe, the disorder of redox homeostasis caused by N-GQDs were indicated by multiple indexes, including GSH depletion, decreased NADPH activity, excessive ROS production and LPO. Similar to other types of graphene-based nanoparticles or QDs, N-GQDs also has been found to be strongly capable of perturbing the redox-sensitive system by inhibiting specific antioxidant enzyme activities in model animals [ 9 , 31 ].…”

Dose‐Dependent Carbon‐Dot‐Induced ROS Promote Uveal Melanoma Cell Tumorigenicity via Activation of mTOR Signaling and Glutamine Metabolism

“…[7] ROS were originally considered a cytotoxic side product of tumor development that could be harnessed to kill tumor cells. [8] However, some studies have shown the opposite-that ROS can promote tumor formation, malignant transformation, and chemotherapy resistance. [9] Oxidative stress occurs when the balance between ROS and antioxidants such as ascorbic acid and glutathione is disrupted and is found in many types of cancer, including melanoma, hepatocellular carcinoma, glioma, and cancers of the breast, pancreas, bladder, colon, lung, and prostate.…”

Promoting Reactive Oxygen Species Generation: A Key Strategy in Nanosensitizer-Mediated Radiotherapy

“…When GQDs are excited, they can generate a variety of ROS, such as 1 O 2 via e − transfer and •OH and O 2 • − derived from electron-hole pairs. Encouraged by these findings, Ruan et al prepared highly oxidized GQDs and demonstrated their powerful radiation enhancement in colorectal carcinoma therapy via the induction of apoptosis [51]. As seen in Figure 7A & B, in the group treated with radiation and GQDs, GQDs were efficiently endocytosed by colorectal carcinoma cells, and cell proliferation was greatly suppressed as a result of the increasing generation of intracellular as well as mitochondrial ROS (Figure 7C), leading to destructive apoptosis (Figure 7D).…”

“…Typical studies are listed in Table 1. Cell growth rates decreased (GQDs + 3 Gy) and cell colony numbers in GQDs + 3 Gy group were lower than those in the 3 Gy group [51] Ag: Silver; Au: Gold; Gd: Gadolinium; GQDs: Graphene quantum dots; HUVECs: Human umbilical vein endothelial cells; NCs: Nanoclusters; NPs: Nanoparticles; ROS: Reactive oxygen species; SER: Sensitization enhancement ratio.…”