title: Dual-responsive magnetic core-shell nanoparticles for nonviral gene delivery and cell separation.
abstract: We present the synthesis of dual-responsive (pH and temperature) magnetic core-shell nanoparticles utilizing the grafting-from approach. First, oleic acid stabilized superparamagnetic maghemite (γ-Fe(2)O(3)) nanoparticles (NPs), prepared by thermal decomposition of iron pentacarbonyl, were surface-functionalized with ATRP initiating sites bearing a dopamine anchor group via ligand exchange. Subsequently, 2-(dimethylamino)ethyl methacrylate (DMAEMA) was polymerized from the surface by ATRP, yielding dual-responsive magnetic core-shell NPs (γ-Fe(2)O(3)@PDMAEMA). The attachment of the dopamine anchor group on the nanoparticle's surface is shown to be reversible to a certain extent, resulting in a grafting density of 0.15 chains per nm(2) after purification. Nevertheless, the grafted NPs show excellent long-term stability in water over a wide pH range and exhibit a pH- and temperature-dependent reversible agglomeration, as revealed by turbidimetry. The efficiency of γ-Fe(2)O(3)@PDMAEMA hybrid nanoparticles as a potential transfection agent was explored under standard conditions in CHO-K1 cells. Remarkably, γ-Fe(2)O(3)@PDMAEMA led to a 2-fold increase in the transfection efficiency without increasing the cytotoxicity, as compared to polyethyleneimine (PEI), and yielded on average more than 50% transfected cells. Moreover, after transfection with the hybrid nanoparticles, the cells acquired magnetic properties that could be used for selective isolation of transfected cells.
authors.affiliation: Makromolekulare Chemie II, Universität Bayreuth , 95440 Bayreuth, Germany.
authors.forename: Alexander P
authors.initials: AP
authors.lastname: Majewski
authors.forename: Anja
authors.initials: A
authors.lastname: Schallon
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; D049109:Cell Proliferation; D002469:Cell Separation; D006224:Cricetinae; D004298:Dopamine / Q000008:administration & dosage; D015259:Dopamine Agents / Q000008:administration & dosage; D005290:Ferric Compounds / Q000737:chemistry*; D018014:Gene Transfer Techniques; D006863:Hydrogen-Ion Concentration; D008280:Magnetics; D008689:Methacrylates / Q000737:chemistry*; D053758:Nanoparticles / Q000737:chemistry*; D009705:Nucleosides; D009757:Nylons / Q000737:chemistry*; D010316:Particle Size; D011094:Polyethyleneimine / Q000737:chemistry; D011108:Polymers / Q000737:chemistry*; D011720:Pyrazoles; D017550:Spectroscopy, Fourier Transform Infrared; D013499:Surface Properties; D013696:Temperature; D014162:Transfection
chemical_list: D015259:Dopamine Agents; D005290:Ferric Compounds; D008689:Methacrylates; D009705:Nucleosides; D009757:Nylons; D011108:Polymers; D011720:Pyrazoles; C407037:poly(2-(dimethylamino)ethyl methacrylate); C000499:ferric oxide; C056881:4-amino-3-(2,3,5-tri-O-benzyl-beta-ribofuranosyl)-5-pyrazole carbonitrile; D011094:Polyethyleneimine; D004298:Dopamine