Photo-cured PMMA/PEI core/shell nanoparticles surface-modified with Gd-DTPA for T1 MR imaging

Herein, we introduced amine-functionalized core-shell nanoparticles (Polymethyl methacrylate/Polyethyleneimine; PMMA/PEI) with surface primary amines (3.15×10⁵ groups/particle) and uniform size distribution (150-200nm) that were prepared by one-step photo-induced emulsion polymerization. Further PEI-surface was modified with diethylenetriamine pentaacetic acid (DTPA) and introduced with Gd(III). The modified particles possessing DTPA can entrap a high content of Gd(III) ions of over 5.5×10⁴Gd/particle with stable chelation (no release of free Gd) at least 7h. The Gd-DTPA-conjugated core-shell nanoparticles (PMMA/PEI-DTPA-Gd NPs) enhanced the MRI intensity more than Primovist (a commercial hepatic contrast agent). Moreover, the PMMA/PEI-DTPA-Gd NPs showed non-cytotoxicity up to 250μM in normal liver cells. Thus, in vitro data suggested the PMMA/PEI-DTPA-Gd NPs is promising delivery system as a superior MRI contrast agent, especially for hepatic lesion targeted MR imaging.