Magnetic Resonance Imaging and Rna Interference of Tumor with Reducible Poly(Urethane-Amine) Nanocomposite System

Gadolinium-based small-molecule contrast agents are commonly utilized in clinics. However, these agents have a short retention time in vivo and possess a certain level of cytotoxicity. The reducible polymer poly(urethane-amine) can increase the relaxation rate and blood circulation time of small-molecule gadolinium chelates. Moreover, the polymer can be used as a gene carrier to bind small interfering RNA (siRNA). We synthesized an active targeting integrated diagnosis and treatment nanocomposite system with reducible poly(urethane-amine) as the carrier. This system incorporated functional units such as MRI contrast agent Gd-diethylenetriamine pentacetate (Gd-DTPA) and siRNA-vascular endothelial growth factor (siRNA-VEGF), and folic acid (FA) modified onto the surface of the polymer directed it to actively target tumor cells, thus improving the imaging effect of MRI. Meanwhlie, siRNA-VEGF carried by the system could reduce the expression of VEGF in tumor cells and inhibited tumor growth. The system showed good biocompatibility and was an integrated system of tumor diagnosis and treatment.