Open AccessLong‐Term Colloidally Stable Aqueous Dispersions of ≤5 nm Spinel Ferrite Nanoparticles
Author(s) -
Eckardt Mirco,
Thomä Sabrina L. J.,
Dulle Martin,
Hörner Gerald,
Weber Birgit,
Förster Stefan,
Zobel Mirijam
Publication year - 2020
Publication title -
chemistryopen
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.644
H-Index - 29
ISSN - 2191-1363
DOI - 10.1002/open.202000313
Subject(s) - nanoparticle , materials science , aqueous solution , spinel , chemical engineering , colloid , ferrofluid , thermal stability , maghemite , iron oxide , trisodium citrate , iron oxide nanoparticles , inorganic chemistry , nanotechnology , chemistry , organic chemistry , metallurgy , physics , quantum mechanics , magnetic field , engineering
Applications in biomedicine and ferrofluids, for instance, require long‐term colloidally stable, concentrated aqueous dispersions of magnetic, biocompatible nanoparticles. Iron oxide and related spinel ferrite nanoparticles stabilized with organic molecules allow fine‐tuning of magnetic properties via cation substitution and water‐dispersibility. Here, we synthesize≤5 nm iron oxide and spinel ferrite nanoparticles, capped with citrate, betaine and phosphocholine, in a one‐pot strategy. We present a robust approach combining elemental (CHN) and thermal gravimetric analysis (TGA) to quantify the ratio of residual solvent molecules and organic stabilizers on the particle surface, being of particular accuracy for ligands with heteroatoms compared to the solvent. SAXS experiments demonstrate the long‐term colloidal stability of our aqueous iron oxide and spinel ferrite nanoparticle dispersions for at least 3 months. By the use of SAXS we approved directly the colloidal stability of the nanoparticle dispersions for high concentrations up to 100 g L −1 .