Near‐Infrared Emission‐Cyanine 5.5 and Doxorubicin Loaded Magnetite Nanoparticles for Dual In Vivo Magnetic Resonance and Biodistribution Imaging

The in vivo imaging of the drug distribution during cancer treatment plays an important role in helping physicians and pharmacists to monitor the progress of treatment and improve the effectiveness of therapy. Our goal in this work was to prepare a multifunctional nano drug delivery system that not only co‐loaded iron oxide nanoparticles (Fe 3 O 4 NPs) and Doxorubicin (Dox) but also attached the near‐infrared fluorescent agent Cyanine 5.5 based on poly(lactide)‐tocopheryl polyethylene glycol 1000 succinate (PLA‐TPGS) copolymer. Cyanine 5.5 was attached to the surface Fe 3 O 4 NPs via the NH−CO chemical bond, followed by co‐loading of Dox onto the PLA‐TPGS copolymer by the emulsion solvent evaporation method. The structural, morphological, dimensional, stability, and optical‐magnetic properties of the as‐synthesized nanosystem were fully characterized. From the drug‐released study, the prolonged release of Dox accelerated with increasing acidic conditions (at pH 5.0 and 6.5), while a slow release was observed at pH 7.4. Through the MTT assay, the nanosystem had cellular toxicity against Hep−G2 and HeLa cell lines with low IC 50 values of 0.42 and 0.78 μg.mL −1 in terms of Dox concentration, respectively. At a magnetic field of 7 T, this nanosystem also exhibited a high r 2 /r 1 ratio of 164.5 and a strong contrast magnetic resonance (MR) image in the liver. In vivo biodistribution studies revealed that the highest fluorescence intensity achived in the liver after 6 h, and the nanosystem was eliminated from the body after at least 24 h. Collectively, these results demonstrated that the PLA‐TPGS‐Fe 3 O 4 ‐Cyanine 5.5‐Dox nanosystem is a good candidate for simultaneously increasing contrast for MR and near‐infrared fluorescence imaging.