Iron oxide/bismuth oxide nanocomposites coated by graphene quantum dots: "Three-in-one" theranostic agents for simultaneous CT/MR imaging-guided in vitro photothermal therapy

Background: The all-in-one nanoprobes (NPs) have drawn biomedical attention in the cancer therapy field due to simultaneously combing the capabilities of therapeutic and diagnostic methods into a single nanoprobe. Method: In this study, we developed a theranostic probe based on superparamagnetic iron oxide (SPIO) and bismuth oxide (Bi2O3) with graphene quantum dots (GQDs) coating to investigate the physical properties for in vitro CT/MR dual-modal biomedical imaging and cancer-specific photothermal therapy (PTT). Result The GQDs-Fe/Bi nanocomposites showed strong light absorbance profile with wide-band in the near-infrared region, without any sharp peak or decline. The highest photo-to-thermal conversion efficacy (n), was found to be 31.8% with the high photostability upon the irradiation of NIR 808-nm laser. The results of in vitro photothermal ablation of cancerous cells demonstrated that the cells significantly killed in the presence of NPs (-53.4%) with a dose-dependent manner in comparison to only laser group (3.0%). In GQDs-Fe/Bi nanocomposites, Bi with a high atomic number (Z = 83) exhibited a superior X-ray attenuation capability (175%) than the clinical CT agent-used dotarem, also, SPIO with excellent magnetization property showed strong T-2-relaxation shortening capability (r(2) = 62.34 mM(-1).s(-1)) as a contrast agent for CT/MR imaging. Conclusion: Our results demonstrate that the developed NPs can incorporate dual-modality imaging capability into a photo absorber for CT/MR imaging-guided tumor PIT.