From Synthesis to Application: The Transformative Role of Graphene-Based Quantum Dots in Biomedicine.

Graphene-based quantum dots (GBQDs) are ultrasmall nanostructures that have attracted growing interest in biomaterial research. Their distinctive characteristics, which include facile synthesis, size-tunable fluorescence, excellent chemical stability, favorable biocompatibility, and inherent antibacterial activity, render them highly suitable for advanced biomedical applications such as multimodal imaging, biosensing, photodynamic therapy, and targeted drug delivery. These advantages position GBQDs as a promising platform for further exploration and expanded utility. This review critically examines how structural and compositional variations in GBQDs govern their optical, electronic, and surface properties, which in turn define their specific roles in bioimaging, biosensing, drug delivery, photodynamic therapy, and antibacterial treatments. A comparative analysis is provided between graphene quantum dots (GQDs) and graphene oxide quantum dots (GOQDs), highlighting subtle differences in structure and properties that inform their respective application scopes, with dedicated attention to evaluating biocompatibility and potential toxicity. Expanding on the biocompatibility assessment, the analysis also addresses the ongoing debate on toxicity by evaluating key factors like size, surface chemistry, dosage, and exposure pathways. By integrating perspectives across these biomedical domains, the review emphasizes the interconnected roles of material design, functionalization, and safety assessment. Finally, major challenges to clinical translation are outlined, including synthesis reproducibility, long-term biodistribution, and degradation mechanisms. Strategic research priorities are proposed to facilitate the transition of GBQDs from laboratory innovation to practical therapeutic applications.