Advancements in Gadolinium–doped Carbon Quantum Dots for Dual–Modal Bioimaging: Synthesis and Applications

Carbon quantum dots (CQDs) represent a revolutionary class of nanoparticles with exceptional biocompatibility, photostability, and tunable optical properties, making them indispensable in biomedical applications. This review focuses on the synthesis and applications of gadolinium-doped carbon quantum dots (Gd-CQDs), particularly in dual-modal bioimaging, which combines magnetic resonance imaging (MRI) and fluorescence imaging. Among various synthesis techniques, the one-step solvent method and the one-pot synthesis method are emphasized, with the latter emerging as a more efficient approach due to its enhanced fluorescence and superior stability. The integration of gadolinium, a widely used MRI contrast agent, into CQDs addresses the challenges posed by conventional gadolinium-based agents, such as their retention in the brain and bones, by offering a safer and more versatile alternative. Gd-CQDs exhibit unique properties, including high biocompatibility, tunable fluorescence, and efficient magnetic resonance contrast, making them ideal candidates for non-invasive diagnostic imaging. Moreover, their potential extends beyond imaging to include applications in targeted drug delivery and real-time monitoring of biological processes. By leveraging advancements in genomics and proteomics, Gd-CQDs pave the way for personalized medical interventions tailored to individual molecular profiles. Future research should focus on optimizing synthesis techniques to enhance particle stability, reduce cytotoxicity, and incorporate multifunctional ligands for improved diagnostic capabilities. This review underscores the transformative potential of Gd-CQDs in advancing medical imaging technologies and bridging the gap between diagnostics and therapeutics.