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Surfactant double layer stabilized magnetic nanofluids for biomedical application.

Authors
  • Tombácz, E
  • Bica, D
  • Hajdú, A
  • Illés, E
  • Majzik, A
  • Vékás, L
Type
Published Article
Journal
Journal of physics. Condensed matter : an Institute of Physics journal
Publication Date
May 21, 2008
Volume
20
Issue
20
Pages
204103–204103
Identifiers
DOI: 10.1088/0953-8984/20/20/204103
PMID: 21694233
Source
Medline
License
Unknown

Abstract

Magnetite nanoparticles were coated with surfactant double layers in order to prepare water based magnetic fluids (MFs). The effects of head group (sulfonate, carboxylate) and alkyl chain length (11-17 C atoms) and the combination of surfactants were studied. Adsorption, dynamic light scattering (DLS) and electrophoretic mobility measurements were performed. The quantity of surfactant varied between 0.3 and 0.5 g, i.e. their specific amount ranges over 1.5-2 mmol g(-1) magnetite in MFs. The adsorption isotherm of Na oleate on magnetite proved the double layer formation with 2 mmol g(-1) saturation value in good harmony with the empirical doses. The effect of diluting MFs, pH and salt concentration was studied. The pH-dependent stability and the salt tolerance of MFs were different owing to the dissociation of the outermost hydrophilic groups and the hydrophobic interactions scaling with the alkyl chain length of surfactant. The hydrophobic interactions are favored only for oleic and myristic acid double layers. In these MFs, aggregation cannot be observed even in fairly dilute systems up to the physiological salt concentration around neutral pH 6-8 favored in biomedical application. The stable oleic and myristic acid double layers can hinder effectively the aggregation of magnetite particles due to the combined steric and electrostatic stabilization.

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