Effect of carbon nanodots on the cellular redox reaction and immune system

Carbon nanodots are ultra-small carbonaceous nanostructures with excellent photoluminescence and cytocompatibility properties, making them suitable for developing excellent bioimaging probes. They exhibit dual properties, generating and scavenging reactive oxygen species, and are used as photosensitizers to produce reactive oxygen species under light and as photothermal agents that transform light energy into heat. This makes it possible to use them in photothermal and photodynamic therapies to treat cancer. They may enter the body by various means, including inhalation, ingestion, or intravenous injection. Once inside, they travel through the bloodstream, infiltrating tissues where they come into contact with the immune system, similar to infectious agents. These nanodots are identified by several receptors on the surface of innate immune cells, such as monocytes and macrophages, which attempt to engulf these nanodots. This interaction can induce a pro-inflammatory (M1) or anti-inflammatory (M2) response, modulating immune activity. This review explores the immuno-toxic potential of carbon nanodots, focusing on their ability to modulate redox balance by catalase, glutathione peroxidase, and superoxide dismutase, which are examples of antioxidant enzymes. Although carbon nanodots have demonstrated a wide range of applications, their effect on the cellular immune system remains largely unexplored. In this study, we primarily addressed the sophisticated impacts of carbon nanodots on the immune system and their diverse processes, such as the many cellular redox reactions implicated in antibacterial and antiviral treatment, wound healing, drug administration, and tumor therapy. As a result, we outline the benefits and difficulties of carbon nanodots in the biomedical domain and discuss their potential in the future development of clinical medicine.