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Updated: Mar 10, 2026
Cell Labeling and Targeting with Superparamagnetic Iron Oxide Nanoparticles
Published on: October 19, 2015
Polyelectrolyte coating on superparamagnetic iron oxide nanoparticles as interface between magnetic core and
Etelka Tombácz1, Katalin Farkas2, Imre Földesi2
1Department of Physical Chemistry and Materials Science , University of Szeged , Aradi vt 1, 6720 Szeged , Hungary.
Abstract:
Nanoparticles do not exist in thermodynamical equilibrium because of high surface free energy, thus they have only kinetic stability. Spontaneous changes can be delayed by designed surface coating. In biomedical applications, superparamagnetic iron oxide nanoparticles (SPIONs) require an optimized coating in order to fulfil the expectation of medicine regulatory agencies and ultimately that of biocompatibility. In this work, we show the high surface reactivity of naked SPIONs due to ≡Fe-OH sites, which can react with H+/OH- to form pH- and ionic strength-dependent charges. We explain the post-coating of naked SPIONs with organic polyacids via multi-site complex bonds formed spontaneously. The excess polyacids can be removed from the medium. The free COOH groups in coating are prone to react with active biomolecules like proteins. Charging and pH- and salt-dependent behaviour of carboxylated SPIONs were characterized quantitatively. The interrelation between the coating quality and colloidal stability measured under biorelevant conditions is discussed. Our coagulation kinetics results allow us to predict colloidal stability both on storage and in use; however, a simpler method would be required to test SPION preparations. Haemocompatibility tests (smears) support our qualification for good and bad SPION manufacturing; the latter 'promises' fatal outcome in vivo.
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