Colloidal stability of amino acid coated magnetite nanoparticles in physiological fluid

We investigated the surface charge effect of surface coating ligands on the colloidal stability of magnetite nanoparticles in a physiological saline solution. We employed the L-lysine and the L-glutamic acid as the Surface coating ligands. We investigated the colloidal stability of the L-lysine and the L-glutamic acid coated magnetite nanoparticles by measuring their precipitation times, hydrodynamic diameter distributions. and zeta potentials in a physiological saline solution. From these three measurements, we found that the L-lysine coated magnetite nanoparticles are more stable as colloids than the L-glutamic acid coated magnetite nanoparticles. Based on the bonding structures of the L-lysine and the L-glutamic acid to magnetite nanoparticles, we successfully discussed the colloidal stability in terms of the surface charge effect of the amino acids. (C) 2008 Elsevier B.V. All rights reserved