Gd(III) ion-chelated supramolecular assemblies composed of PGMA-based polycations for effective biomedical applications

Ethanolamine (EA) or ethylenediamine (ED)-functionalized poly(glycidyl methacrylate) (PGMA), namely PGEA or PGED, has recently been used as effective gene carriers because of their low cytotoxicity and high transfection efficiency. In this study, a series of PGMA-based supramolecular polycations (PGED-Gd@PGEAs) with magnetic resonance imaging (MRI) functions were readily constructed by assembling multiple adamantine-headed star PGEA (Ad-PGEA) units with a versatile PGED-CD-Gd backbone, which possessed numerous flanking beta-cyclodextrin species and Gd3+ ions. The properties of different PGED-Gd@PGEA vectors were systematically characterized, including the plasmid DNA condensation ability, cytotoxicity, gene transfection efficiency, cellular uptake and MRI function. Such supramolecular gene vectors had lower toxicity than 'gold standard' polyethylenimine (PEI, 25 kDa). Furthermore, PGED-Gd@PGEAs exhibited significantly higher transfection efficiencies than PEI or the constituent units (PGED-CD-Gd and Ad-PGEA). The chelation of Gd3+ ions imparted the PGED-Gd@PGEA vectors with a good MRI ability without obvious adverse effects. The present design of PGMA-based supramolecular polycations with Gd3+ chelation would provide useful information for the development of low-toxicity and high-efficiency multifunctional gene delivery systems.