The Influence of Cyanine 5.5 and Doxorubicin on Cell Cycle Arrest, Magnetic Resonance, and Near-Infrared Fluorescence Optical Imaging for Fe3O4-Encapsulated PLA-TPGS Nanoparticles.

The combination of magnetic resonance imaging (MRI)/near-infrared (NIR) fluorescence signals and chemotherapy agents has been developed for cancer diagnosis and treatment. In this work, we investigated the impacts of NIR Cyanine 5.5 fluorescence and Doxorubicin on cell cycle arrest, magnetic resonance, and NIR fluorescence optical imaging for Fe3O4-encapsulated nanosystems based on poly(lactide)-tocopheryl polyethylene glycol succinate (PLA-TPGS) copolymer. Although Cyanine 5.5 and Fe3O4 nanoparticles (NPs) are less cytotoxic than Doxorubicin, they present a cytostatic effect, inducing cell cycle arrest at the G2/M phase in human brain adenocarcinoma (CCF-STTG1) cells. For MRI applications, the permeability of the PLA-TPGS copolymer coating layer to water molecules might lengthen the translational diffusion time (τD), causing the high relaxivity ratio (r2/r1) in Fe3O4 bare NPs under an applied magnetic field (7 Tesla). Astonishingly, the chemical structures of Cyanine 5.5 and Doxorubicin significantly contribute to the enhancement of the T2 relaxivities of Fe3O4 NPs through π-π and p-π conjugation. Furthermore, the radiance ratio and signal-to-noise ratio enhancement and a slight blue shift in the optimal excitation and emission wavelengths were recorded. These findings show the potential for in vivo MRI and NIR bioimaging experiments of the nanoparticles.