Composition and hydrophilicity control of Mn-doped ferrite (Mn_xFe_3−xO₄) nanoparticles induced by polyol differentiation

Abstract

Manganese doped ferrite (MnxFe3-xO4) nanoparticles with x = 0.29-0.77 were prepared under solvothermal conditions in the presence solely of a polyol using the trivalent manganese and iron acetylacetonates as precursors. In this facile approach, a variety of polyols such as polyethylene glycol (PEG 8000), tetraethylene glycol (TEG), propylene glycol (PG) and a mixture of TEG and PG (1 : 1) were utilized in a triple role as a solvent, a reducing agent and a surface-functionalizing agent. The composition of the fine cubic-spinel structures was found to be related to the reductive ability of each polyol, while determination of structural characteristics plus the inversion parameter (i = 0.18-0.38) were provided by X-ray absorption near edge structure (XANES) and extended X-ray absorption fine structure (EXAFS) spectroscopy at both the Fe and Mn K-edges. The saturation magnetization increased up to 80 emu g(-1) when x = 0.35 and i = 0.22. In addition, the as-prepared nanocrystals coated with PEG, PG and PG&TEG showed excellent colloidal stability in water, while the TEG-coated particles were not water dispersible and converted to hydrophilic when were extra PEGylated. Measurements of the (1)H NMR relaxation in water were carried out and the nanoprobes were evaluated as potential contrast agents.

The Effect of Polyol Composition on the Structural and Magnetic Properties of Magnetite Nanoparticles for Magnetic Particle Hyperthermia

“…Given that the reducing ability of a polyol depends on its molecular weight, among triethyleneglycol, PEG-1000, and PEG-8000, triethyleneglycol shows the highest reductive ability and PEG-8000 the weakest [46,49]. When an additional reducing agent participates in the synthesis, the mechanism which affects the system iron precursor-NaBH 4 -polyol is quite complicated.…”

Tailoring Ca-Based Nanoparticles by Polyol Process for Use as Nematicidals and pH Adjusters in Agriculture

“…The percentages of paralysed J2 in the microwell assays were corrected by removal of the natural death/paralysis percentage in the water control, according to the Schneider Orelli formula 33 and they were analysed (ANOVA) after being combined over time: shown before by us and others. 26,27,46 TEG has a lower boiling point than PEG, 314 o C and >350 o C, respectively. Therefore, the oxidation polyol pathway is more favored in TEG resulting in the production of CO2 inside the autoclave.…”

“…This suggests that CaCO3 is formed as an outer shell. 61 in the current study, as polyols decompose in the same vicinity as Ca(OH)2, right after 400 o C. 26,27,[44][45][46] Moreover, high molecular weight polyols such as PEG form a double layer of coating around the surface of the NPs 46, 63 that decomposes around the same vicinity as CaCO3, just above 550 o C. Fig. 2A and 2B) is not a case of double layer but the decomposition of CaCO3.…”

“…The mechanistic representation of the polyol process is still in the build, polyols participate in red/ox, complexation and decomposition reactions with the cations and anions of the solution and form intermediates before yielding nanoparticles. 26,27,[39][40][41][42][43][44][45][46] The products of the red/ox reactions are oxidized derivatives of polyols, like glycolaldehyde, glycoxylic acid, glycolic acid, oxalic acid, oxalates and CO2. Moreover, it has been shown by us and others that polyols of higher reductive ability and cations/anions of higher oxidizing activity react in situ with polyols favoring the oxidation pathway while increasing the effectiveness of polyols as carbon sources.…”

“…Moreover, it has been shown by us and others that polyols of higher reductive ability and cations/anions of higher oxidizing activity react in situ with polyols favoring the oxidation pathway while increasing the effectiveness of polyols as carbon sources. 26,27,39,41,[44][45][46]…”