Functionalized Graphene Quantum Dots (FGQDs): A review of their synthesis, properties, and emerging biomedical applications

•Importance of synthetic methods for functionalized GQDs (FGQDs) is discussed.•FGQD with various organic moieties and incorporation mechanisms is discussed.•Reviews FGQD applications in biosensors, bioimaging, and drug delivery applications. Graphene quantum dots (GQDs) have attracted significant attention due to their unique electronic, optical, physical, and chemical properties. As nanoscale fragments of graphene rich in electrons, GQDs offer enhanced capabilities that elevate their potential across a wide range of applications. This review paper delves into the synthesis, characterization, and applications of functionalized graphene quantum dots (FGQDs), which exhibit exceptional photoelectronic properties resulting from quantum confinement and edge effects. These features position FGQDs as promising materials for optoelectronic technologies. The review also highlights various functionalization strategies, providing valuable insights for researchers seeking to optimize GQDs for specific applications. By understanding the correct functionalization techniques, researchers can tailor the properties of FGQDs to enhance their performance in a range of applications. This article offers an in-depth discussion of synthetic approaches for producing FGQDs with diverse chemical groups and functionalities, alongside a thorough overview of characterization techniques, ranging from morphological and crystallographic analysis to componential and absorption spectroscopy. Furthermore, the review explores the growing potential of FGQDs in biomedical applications, including biosensing, bioimaging, drug delivery, and therapeutics. It underscores the advances in research and development that are crucial for unlocking the full biomedical potential of FGQDs, while also addressing the challenges that remain to be tackled in the future. As the field continues to evolve, the insights presented in this review provide a solid foundation for future breakthroughs in the synthesis and application of FGQDs.