Multifunctional GQDs-Coated Fe/Bi Nanohybrids for CT/MR Dual Imaging and in vitro Photothermal Therapy

Introduction: The multipurpose nanocomposites have gained growing biomedical attention as promising nanotheranostics to improve The effectiveness of cancer treatment, which concurrently combine advantages of the therapeutic and diagnostic techniques into one nanosystem. The “all-in on” probes not only help to ablate cancerous tumors, but also allow to optimize and monitoring of treatment.  Materials and Methods: iron/bismuth nanohybrid was synthesized in presence of graphene quantum dots for the co-integration of diagnostic and therapeutic functions into a single nanoprobe (referred to as GQDs-Fe/Bi NPs). Then, for further applications, blood compatibility and cytotoxicity, as important tissues, of different concentration of GQDs-Fe/Bi NPs were investigated by hemolysis test and MTT test, respectively. A 1.5 T MRI scanner (Siemens Avanto- Germany) was employed to measure MR contrast ability of GQDs-Fe/Bi NPs with various concentrations of Fe. In additional, the phantom CT images were taken at the various concentrations of the Bi and iodine using a clinical CT scanner (GE HiSpeed) at operating voltages of 80,120 and 140 kVp. The acquired images were analyzed with imageJ software. To study the photothermal performance, the GQDs-Fe/Bi NPs suspension with a series of concentrations of active Bi metal were exposed to a NIR laser (808 nm, 1.7 W ・cm−2) for 10 min.   Results: Such theranostic agent not only shows strong near-infrared (NIR) absorbance, but also offers high contrast for X-ray computed tomography (CT) and magnetic resonance (MR) imaging to the imaging-guided NIR laser irradiation deliver and selectively heating of tumor. Fe3O4 component involved in the hybrid showed the good magnetization property (48.59 emu/g) with excellent performance on magnetic resonance imaging and high relaxivity time (62.34 mM−1 s−1). Synergistically, the presence of the Bi component with high atomic number (Z=83) in the GQDs-Fe/Bi nanohybrid offered high- X-ray contrast for CT imaging. Furthermore, thanks to the high photothermal conversion efficiency of 31.88%, co-delivery of GQDs-Fe/Bi NPs and NIR-radiation can effectively kill the cancer cells.  Conclusion: the high theranostic performance of GQDs-Fe/Bi NPs can simultaneously use for CT/MR imaging-guided cancer photothermal therapy purposes.