Tuneable carbon dots coated iron oxide nanoparticles as superior <i>T</i><sub>1</sub> contrast agent for multimodal imaging

Abstract

Background and purpose: Multifunctional hybrid nanoparticles garner heightened interest for prospective biomedical applications, including medical imaging and medication administration, owing to their synergistic benefits of constituent components. Therefore, we demonstrated an optimized protocol for synthesizing magnetofluorescent nanohybrids comprising fluorescent carbon dots with magnetic nanoparticles. Experi­mental approach: Carbon dot-coated iron oxide nanoparticles (CDs@Fe2O3) were synthesized with varying citric acid concentrations by a one-pot hydrothermal synthesis method for the development of a low-cost and biocompatible contrast agent (CA) for enhanced multimodal imaging (fluorescent and T1 and T2 weighted magnetic resonance imaging (MRI)) to replace the conventional CAs. Key results: The physico­chemical characterization of the synthesized CDs@Fe2O3 revealed that 3 g of citric acid used for the synthesis of nanoparticles, keeping Fe(II) and Fe(III) ratio 1:2 provides higher stability of -78 mV zeta potential, saturation magnetization of 24 emu/g, with a hydrodynamic diameter of 68 nm. Carbon coating affects surface spins on Fe2O3, resulting in fewer surface-based relaxation centres, making T1 relaxation relatively more prominent. Furthermore, the surface-engineered iron oxide NPs are efficient in producing both T1 and T2 weighted MRI as well as fluorescence-based imaging. The molar relaxivity and molar radiant efficiency derived from phantom studies demonstrate their effectiveness in multimodal medical imaging. The cyto­toxicity assay, haemolysis assay, haematology, and histopathology studies show that the optimized CDs@Fe2O3 are biocompatible, haemocompatible, and negligibly toxic. Conclusion: We can conclude the significant potency of CDs@Fe2O3 for multimodal diagnosis.

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