Refinement of Magnetite Nanoparticles by Coating with Organic Stabilizers

Abstract

Magnetite nanoparticles are of great importance in nanotechnology and nanomedicine and have found manifold applications. Here, the effect of coating of magnetite nanoparticles with organic stabilizers, such as O-phosphoryl ethanolamine, glycerol phosphate, phospho-l-ascorbic acid, phospho-d,l-serine, glycolic acid, lactic acid, d,l-malic acid, and d,l-mandelic acid was studied. Remarkably, this procedure led to an improvement of saturation magnetization in three cases rather than to an unfavorable decrease as usually observed. Detailed X-ray powder diffraction investigations revealed that changes in the average crystallite occurred in the coating process. Surprisingly, changes of the average crystallite sizes in either direction were further observed, when the exposure time to the stabilizer was increased. These results imply a new mechanism for the well-known coating of magnetite nanoparticles with stabilizers. Instead of the hitherto accepted simple anchoring of the stabilizers to the magnetite nanoparticle surfaces, a more complex recrystallization mechanism is likely, wherein partial re-dispersion of magnetite moieties from the nanoparticles and re-deposition are involved. The results can help producers and users of magnetite nanoparticles to obtain optimal results in the production of core shell magnetite nanoparticles.

Microwave-Assisted Synthesis of Water-Dispersible Humate-Coated Magnetite Nanoparticles: Relation of Coating Process Parameters to the Properties of Nanoparticles

“…This unusual behavior is primarily due to the interaction of the functional groups of the polyanion with iron atoms on the surface of the nanoparticles. The most probable assumption is the interaction of the carboxy group with surface iron atoms, as was shown earlier when using another capping agent, including oleic acid [66][67][68][69]. It is surprising that, in order to achieve improved magnetic and colloidal (will be considered later) properties, it is not necessary to stabilize the entire surface of nanoparticles, but it is sufficient to stabilize only the most active metal atoms to achieve a Fe-O bond length on the surface of the nanoparticle comparable with the bond length in the bulk [70].…”

Magnetic Colloidal Particles in Combinatorial Thin-Film Gradients for Magnetic Resonance Imaging and Hyperthermia

“…No stabilizing agent was used during the synthesis to get superparamagnetic nanoparticles. Agglomeration of particles was due to the attractive forces between the magnetic nanoparticles [18]. Some partial aggregation is probably caused by the preparation of the samples for TEM measurement.…”

Surface Functionalization of Iron Oxide Nanoparticles with Gallic Acid as Potential Antioxidant and Antimicrobial Agents

“…Magnetic IONPs owe protuberant antioxidant activity against oxidative damage-related diseases [ 19 , 20 , 21 , 22 , 23 , 24 , 25 ]. However, there are several factors that strongly affect nanomaterials antioxidant activity for instance chemical composition, surface charge, particle size, and coating of the surface [ 6 , 26 , 27 , 28 , 29 ]. The surface coating could be biocompatible, nontoxic and allow targeted drug delivery [ 30 , 31 , 32 , 33 , 34 , 35 ].…”