title: PDMAEMA-grafted core-shell-corona particles for nonviral gene delivery and magnetic cell separation.
abstract: Monodisperse, magnetic nanoparticles as vectors for gene delivery were successfully synthesized via the grafting-from approach. First, oleic acid stabilized maghemite nanoparticles (γ-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 (γ-Fe2O3@silica@PDMAEMA) with an average grafting density of 91 polymer chains of DP(n) = 540 (PDMAEMA540) 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-K1 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.
authors.affiliation: Makromolekulare Chemie II, Universität Bayreuth, 95440 Bayreuth, Germany.
authors.forename: Alexander P
authors.initials: AP
authors.lastname: Majewski
authors.forename: Ullrich
authors.initials: U
authors.lastname: Stahlschmidt
authors.forename: Valérie
authors.initials: V
authors.lastname: Jérôme
authors.forename: Ruth
authors.initials: R
authors.lastname: Freitag
authors.forename: Axel H E
authors.initials: AH
authors.lastname: Müller
authors.forename: Holger
authors.initials: H
authors.lastname: Schmalz
mesh_terms: D000818:Animals; D016466:CHO Cells; D002469:Cell Separation / Q000379:methods*; D002470:Cell Survival / Q000187:drug effects; D006224:Cricetinae; D003412:Cricetulus; D005290:Ferric Compounds / Q000737:chemistry*; D006863:Hydrogen-Ion Concentration; D007928:Lethal Dose 50; D060328:Magnetic Phenomena; D008689:Methacrylates / Q000737:chemistry*; D051379:Mice; D053758:Nanoparticles / Q000737:chemistry* / Q000633:toxicity; D010316:Particle Size; D058105:Polymerization; D011109:Polymethacrylic Acids / Q000138:chemical synthesis* / Q000737:chemistry; D014162:Transfection / Q000379:methods
chemical_list: D005290:Ferric Compounds; D008689:Methacrylates; D011109:Polymethacrylic Acids; C000499:ferric oxide; C049840:2-(dimethylamino)ethyl methacrylate