Construction of Paramagnetic Manganese-chelated Polymeric Nanoparticles Using Pyrene-end-modified Double-Hydrophilic Block-Copolymers for Enhanced Magnetic Resonance Relaxivity: A Comparative Study with Cisplatin Pharmacophore

Cationic metal-mediated self-assembly of double-hydrophilic block-copolymers (DHBCs) has been of great interest for the preparation of hybrid nanoparticles for versatile applications. Among many functional transition metal ions, manganese (MnII) is a highly attractive element due to the paramagnetic property with high coordination number. However, MnII does not lead to the efficient self-assembly of DHBCs because of the relatively high aqueous solubility of coordinated MnII. This article reports a facile method for direct conjugation of MnII ions inside sterically stabilized polymer assemblies, composed of pyrene-end-modified DHBCs. Nitroxide-mediated radical polymerization was used to prepare the poly(ethylene glycol)-b-poly(acrylate) DHBC precursor, followed by the end-modification with pyrene maleimide via radical exchange reaction. Employing the self-associated DHBCs as a nanoscale template, the simple addition of MnII enables a large number of polyvalent MnII ions to be immobilized at the chelating b...