Synthesis of cationic magnetite nanoparticles for intracellular protein delivery

Intracellular protein delivery shows great promise in the treatment of various diseases. However, therapeutic applications of this method are limited by its low delivery efficiency and poor targeting ability. As one of most important drug delivery cargoes, Fe₃O₄ nanoparticles (nFe₃O₄) have attracted much attention for both therapeutic and diagnostic applications, especially for targeting drug delivery. To use nFe₃O₄ for protein delivery, a simple but effective modification of nFe₃O₄ is critical to attach proteins on its surface. In this work, by designing and synthesizing cationic poly(2‐(dimethylamino)ethyl methacrylate) (PDMA)‐grafted nFe₃O₄ via in situ atom transfer radical polymerization (ATRP), we demonstrate a simple solution to improve interactions between nFe₃O₄ and proteins. With the grafted PDMA on the surface, nFe₃O₄ exhibits not only significant enhancement in dispersibility and stability in aqueous phase, but also an excellent capability to attach negative‐charged proteins. Moreover, with the assistance of external magnetic field, PDMA‐grafted nFe₃O₄ can be used as a targetable vector to deliver proteins into specific cells. This work provides a novel platform based on cationic magnetite nanoparticles that can deliver therapeutic proteins into specific sites for the treatment of various diseases. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40260.