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Majewski, Alexander P. ; Stahlschmidt, Ullrich ; Jérôme, Valérie ; Freitag, Ruth ; Müller, Axel H. E. ; Schmalz, Holger:
PDMAEMA-Grafted Core-Shell-Corona Particles for Nonviral Gene Delivery and Magnetic Cell Separation.
In: Biomacromolecules.
Bd. 14
(2013)
Heft 9
.
- S. 3081-3090.
ISSN 1526-4602
DOI: https://doi.org/10.1021/bm400703d
Abstract
Monodisperse, magnetic nanoparticles as vectors for gene delivery were successfully synthesized via the grafting-from approach. First, oleic acid stabilized maghemite nanoparticles (gamma-Fe2O3) were encapsulated with silica utilizing a reverse microemulsion process with simultaneous functionalization with initiating sites for atom transfer radical polymerization (ATRP). Polymerization of 2-(dimethylamino)-ethyl methacrylate (DMAEMA) from the core-shell nanoparticles led to core-shell-corona hybrid nanoparticles (gamma-Fe2O3@silica@PDMAEMA) with an average grafting density of 91 polymer chains of DPn = 540 (PDMAEMA(540)) per particle. The permanent attachment of the arms was verified by field-flow fractionation. The dual-responsive behavior (pH and temperature) was confirmed by dynamic light scattering (DLS) and turbidity measurements. The interaction of the hybrid nanoparticles with plasmid DNA at various N/P ratios (polymer nitrogen/DNA phosphorus) was investigated by DLS and zeta-potential measurements, indicating that for N/P >= 7.5 the complexes bear a positive net charge and do not undergo secondary aggregation. The hybrids were tested as transfection agents under standard conditions in CHO-KI and L929 cells, revealing transfection efficiencies >50% and low cytotoxicity at N/P ratios of 10 and 15, respectively. Due to the magnetic properties of the hybrid gene vector, it is possible to collect most of the cells that have incorporated a sufficient amount of magnetic material by using a magnetic activated cell sorting system (MACS). Afterward, cells were further cultivated and displayed a transfection efficiency of ca. 60% together with a high viability.