Synthesis, Surface Modifications, and Size‐Sorting of Mixed Nickel–Zinc Ferrite Colloidal Magnetic Nanoparticles

Abstract

We report on the spontaneous covalent growth of monomolecular adlayers on mixed nickel-zinc nanoferrite colloidal suspensions (ferrofluids). Synthesized nanoparticles were subjected to surface modification by means of acid chloride chemistry, leading to the formation of covalent bonds between the hydroxy groups at the nanoparticle surface and the acid chloride molecules. This procedure can be easily tailored to allow for the formation of adlayers containing both hydrophobic and hydrophilic regions stacked at predetermined distances from the magnetic core, and also providing the nanoferrites with functional carboxy groups capable of further modifications with, for example, drug molecules. Here, fluorophore aminopyrene molecules were bound to such modified nanoferrites through amide bonds. We also used the same chemistry to modify the surface with covalently bound long-chain palmitoyl moieties, and for comparison we also modified the nanoferrite surface by simple adsorption of oleic acid. Both procedures made the surface highly hydrophobic. These hydrophobic colloids were subsequently spread on an aqueous surface to form Langmuir monolayers with different characteristics. Moreover, since uniformity of size is crucial in a number of applications, we propose an efficient way of sorting the magnetic nanoparticles by size in their colloidal suspension. The suspension is centrifuged at increasing rotational speed and the fractions are collected after each run. The mean size of nanoferrite in each fraction was measured by the powder X-ray diffraction (PXRD) technique.

Hybrid System for Local Drug Delivery and Magnetic Hyperthermia Based on SPIONs Loaded with Doxorubicin and Epirubicin

“…On the other hand, for both DOPC and cardiolipin, monolayer surface area decreased relative to the highest drug concentration at about 15% (cardiolipin) and about 30% (DOPC) in both environments in which the studies were performed. The use of the conjugate limited the penetration of antibiotics into a polar head group of lipids, which can be caused by the spatial location of the molecules and the lack of access to certain functional groups of the drug molecule that may interact with the membrane, see Figure 7 [60]. When considering the π-A curves for SPION@CA_Epi, analog to the doxorubicin conjugate can be seen.…”

Lanthanide-Doped SPIONs Bioconjugation with Trastuzumab for Potential Multimodal Anticancer Activity and Magnetic Hyperthermia

“…The absorption band at ca. 1410 cm −1 and 1620 cm −1 can be related to the vibrations of -OH from water molecules still adsorbed on the surface, as well as surface-bound -OH groups present on the nanoferrite surface [34]. Fe 3 O 4 -CEPA ( Figure 3, red curve) reveals characteristic absorption at 1630 cm −1 , corresponding to C=O stretching vibrations in protonated-COOH group, which subsequently takes part in trastuzumab conjugation through the carbodiimide (EDC/NHS) procedure.…”

Influence of Zn+2 Doping on Ni-Based Nanoferrites; (Ni1−x ZnxFe2O4)

“…Besides this, spinel ferrite nanoparticles have attained a lot of interest due to their unique magnetic, thermal electrical, dielectric, or catalytic properties for high-tech applications in industries as an inductive or capacitive material, ferrofluids, disk recording, microwave absorbers, transformers, electric generators, or electrical device, etc. [17,18,19]. The spinel structure allows the amalgamation of various metallic ions without altering the spinel crystal structure modifying electrical structural, dielectric, or magnetic properties of spinel ferrites via substituting M 2 ions [20,21,22,23].…”