Unveiling the Physicochemical Features of CoFe₂O₄ Nanoparticles Synthesized via a Variant Hydrothermal Method: NMR Relaxometric Properties

Abstract

A series of CoFe 2 O 4 nanoparticles were formed through a variant hydrothermal synthesis based in a self-assembly oil-water system in autoclaves at 200 °C in the presence of octadecylamine and the trivalent iron and cobalt acetylacetonates. The variation of the water content, the different valence of cobalt precursor (Co(II) and Co(III)) as well as Fe:Co precursor ratios (2:1 and 1:1) were studied. CoFe 2 O 4 nanoparticles with a size range 9-16 nm of high crystallinity and enhanced saturation magnetization (~89 emu g -1 ) have been isolated and characterized. Raman spectroscopy provided information concerning the lattice strain, while incorporation of Co 2+ at T d sites of the spinel indicated a different inversion degree (0.67-0.60) among the samples. EPR studies showed that EPR signal and spin relaxation process were size dependent and influenced by aggregation effects.CoFe 2 O 4 nanoparticles were converted to dual agents via a reaction between the free amine groups of the organic coating and the sulfonyl group of the fluorescent dye sulforhodamine B acid chloride (SRB) and NMR relaxometric properties were measured.The relatively high transverse relaxivity values, r 2 (232.0-130.3 mM -1 s -1 ) were attributed to nanocluster effects in aqueous suspensions in respect with the amount of SRB and encourage their potential application as versatile agents in theranostics.

RETRACTED: Structural and Magnetic Response in Bimetallic Core/Shell Magnetic Nanoparticles

“…Figure 2a represents Raman spectrum for core nanoparticles at room temperature. In this spectrum, the highest frequency mode at 708 cm −1 corresponds to the lattice site effects at tetrahedral sites (T-site), while the peak at 472 cm −1 reflects lattice site effects in the octahedral site (O-site) [31]. Along with these, the vibrational mode positions 537, 648, 814, and 915 cm −1 were also observed in the spectrum.…”

Nanoplatforms of Manganese Ferrite Nanoparticles Functionalized with Anti‐Inflammatory Drugs

“…Additionally, the trivalent instead of the divalent manganese acetylacetonate precursor has been used for the synthesis of MnFe 2 O 4 MNPs as higher magnetization values were expected. The similar decomposition/dissociation rate of Mn III with that one of Fe III precursor can lead to variations of manganese ions in tetrahedral ( T d ) and octahedral (O h ) sites in the spinel structure and eventually to higher magnetization values. However, the isolated MnFe 2 O 4 MNPs with the divalent Mn II precursor showed higher magnetization values (64 emu/g) instead to those of Mn III precursor (10 emu/g) (Figure S1), and under this evidence we did not proceed further with this sample.…”

Facile synthesis, morphological, structural, photocatalytic and optical properties of CoFe2O4 nanostructures

“…The calculated average crystallite size and lattice constants of the prepared CoFe 2 O 4 samples are shown in Table 1. four peaks at 303 cm −1 (E g ), 467 cm −1 (T 2g (2)), 625 cm −1 (A 1g (2)) and 679 cm −1 (A 1g (1)) which correspond to the Raman active modes of CoFe 2 O 4 [44,45]. Band at 679 cm −1 is the fundamental A 1g (1) mode and is attributed to O atom symmetric stretching with reference to tetrahedral void metal ion [45,46].…”

“…The 625 cm −1 peak is ascribed to A 1g (2) sub-band mode from Co 2+ distribution at octahedral and tetrahedral sites [45]. Peaks at 303 and 467 cm −1 are the T 2g (2) and E g modes, respectively, and are from the antisymmetric and symmetric bending of O in M-O bond (Fe-O and Co-O) around the octahedral void (O h ) [44]. A summary of the Raman modes observed for all the prepared samples is presented in Table 2.…”