title: Enhanced stability of polyacrylate-coated magnetite nanoparticles in biorelevant media.
abstract: Magnetite nanoparticles (MNPs) were prepared by alkaline hydrolysis of Fe(II) and Fe(III) chlorides. Adsorption of polyacrylic acid (PAA) on MNPs was measured at pH=6.5±0.3 and I=0.01 M (NaCl) to find the optimal PAA amount for MNP stabilization under physiological conditions. We detected an H-bond formation between magnetite surface groups and PAA by ATR-FTIR measurements, but bonds of metal ion-carboxylate complexes, generally cited in literature, were not identified at the given pH and ionic strength. The dependence of the electrokinetic potential and the aggregation state on the amount of added PAA at various pHs was measured by electrophoretic mobility and dynamic light-scattering methods. The electrokinetic potential of the naked MNPs was low at near physiological pH, but PAA adsorption overcharged the particles. Highly negatively charged, well-stabilized carboxylated MNPs formed via adsorption of PAA in an amount of approximately ten times of that necessary to compensate the original positive charge of the magnetite. Coagulation kinetics experiments revealed gradual enhancement of salt tolerance at physiological pH from ~0.001 M at no added PAA up to ~0.5 M at 1.12 mmol/g PAA. The PAA-coated MNPs exert no substantial effect on the proliferation of malignant (HeLa) or non-cancerous fibroblast cells (MRC-5) as determined by means of MTT assays.
authors.affiliation: University of Szeged, Department of Physical Chemistry and Material Science, Szeged, Hungary. angela.hajdu@net.sote.hu
authors.forename: Angéla
authors.initials: A
authors.lastname: Hajdú
authors.forename: Márta
authors.initials: M
authors.lastname: Szekeres
authors.forename: Ildikó Y
authors.initials: IY
authors.lastname: Tóth
authors.forename: Rita A
authors.initials: RA
authors.lastname: Bauer
authors.forename: Judith
authors.initials: J
authors.lastname: Mihály
authors.forename: István
authors.initials: I
authors.lastname: Zupkó
authors.forename: Etelka
authors.initials: E
authors.lastname: Tombácz
mesh_terms: D000180:Acrylic Resins / Q000737:chemistry*; D000327:Adsorption; D002470:Cell Survival / Q000187:drug effects; D002712:Chlorides / Q000737:chemistry*; D003470:Culture Media; D004337:Drug Carriers / Q000138:chemical synthesis* / Q000494:pharmacology; D004355:Drug Stability; D004586:Electrophoresis; D005290:Ferric Compounds / Q000737:chemistry*; D005296:Ferrous Compounds / Q000737:chemistry*; D005347:Fibroblasts / Q000187:drug effects; D006367:HeLa Cells; D006801:Humans; D006860:Hydrogen Bonding; D006863:Hydrogen-Ion Concentration; D006868:Hydrolysis; D007700:Kinetics; D058185:Magnetite Nanoparticles / Q000737:chemistry*; D009994:Osmolar Concentration; D010316:Particle Size; D017550:Spectroscopy, Fourier Transform Infrared; D055672:Static Electricity
chemical_list: D000180:Acrylic Resins; D002712:Chlorides; D003470:Culture Media; D004337:Drug Carriers; D005290:Ferric Compounds; D005296:Ferrous Compounds; D058185:Magnetite Nanoparticles; C006903:carbopol 940; C029451:ferrous chloride; C024555:ferric chloride