Synthesis of PAMAM-g-PEG-g-DS-g-RB@IO towards dual-modal imaging in atherosclerosis

This study aimed to synthesize a dual-modal magnetic resonance imaging (MRI)/fluorescence imaging (FLI) nanoprobe in order to detect atherosclerosis. Herein, we had prepared the polyamidoamine-graft-poly (ethylene glycol) (PAMAM-g-PEG) as the carrier. Dextran sulfate (DS) and Rhodamine B (RB) were grafted to PAMAM-g-PEG continuously through reductive amination and amidation reaction to synthesize PAMAM-g-PEG-g-DS-g-RB. The structure of PAMAM-g-PEG-g-DS-g-RB was characterized through nuclear magnetic resonance (¹H-NMR) and Fourier transform infrared spectroscopy (FTIR). A new water-soluble superparamagnetic iron oxide nanoparticles (IONPs) has been synthesized through simple ligand exchange between the iron oxide nanaparticles and PAMAM-g-PEG-g-DS-g-RB. The analysis of transmission electron microscopy (TEM) indicated that micelles were well dispersed in water and had uniform sizes. The result of thermogravimetric analysis (TGA) proved that about 83% (mass fraction) polymers were coated on the surface of IONPs. The MRI in vitro evaluation demonstrated a high R2 value (130.8 mM^?1s^?1) to be served as a T2-weighted contrast agent. The cell counting kit (CCK) assay showed no significant toxicity in RAW264.7. The above results confirmed that PAMAM-g-PEG-g-DS-g-RB@IO could play an significant role of MRI and FLI in the atherosclerosis.