Plasmid-DNA Delivery by Covalently Functionalized PEI-SPIONs as a Potential ‘Magnetofection’ Agent oleh René Stein, Felix Pfister, Bernhard Friedrich, Pascal-Raphael Blersch, Harald Unterweger, Anton Arkhypov, Andriy Mokhir, Mikhail Kolot, Christoph Alexiou, Rainer Tietze