Preparation, physicochemical characterization, and AC induction heating properties of colloidal aggregates of ferrimagnetic cobalt ferrite nanoparticles coated with a bio-compatible polymer

A nudge over the relaxation plateau: effect of pH, particle concentration, and medium viscosity on the AC induction heating efficiency of biocompatible chitosan-coated Fe3O4 nanoparticles

“…The average zeta potentials were ∼51 ± 2.2 mV, ∼37 ± 2.8 mV, ∼22 ± 3.2 mV, ∼19 ± 3.5 mV and ∼−13 ± 3.3 mV at pH ∼2, ∼3, ∼4, ∼6 and ∼8, respectively. Deprotonation of the amine groups at higher pH [8] caused the zeta potential to decrease, and the high positive zeta potential at pH ∼2 was due to the surface attached -NH 3 + ions [14]. This agreed with the previously published reports showing a decrease in zeta potential with increasing medium pH for chitosan-coated nanostructures [51,52].…”

“…Subsequently, an additional ∼9.8% weight loss was observed at T ∼230 °C-470 °C due to the progressive degradation and removal of chitosan. The observed degradation temperature was similar to the previously reported temperature range of ∼200 °C-400 °C for the degradation of the chitosan polymer [14,32]. It has been reported that chitosan degradation involves the pyrolysis and rupture of the polysaccharide chains initiated through a random split of the glycosidic bonds [33].…”

“…The presence of environmental CO 2 resulted in the absorption band at ∼2360 cm −1 . The yellow-shaded region in figure 1(c) indicated the characteristic absorption bands for chitosan, such as amide-I and amide-II at ∼1620 cm −1 , and ∼1528 cm −1 , respectively [14,36], C-O-C and C-N stretching vibrations at ∼1122 cm −1 , and ∼1339 cm −1 , respectively [37,38], and C-O stretching at ∼1404 cm −1 , and ∼1049 cm −1 [37,39]. These specific absorption bands provided compelling evidence for the presence of chitosan coating.…”

“…On the other hand, deprotonation of the amine groups at higher pH makes chitosan increasingly insoluble in aqueous dispersions, giving rise to significant colloidal destabilization [8]. Chitosancoated MNPs have been used in a variety of biomedical applications, like magnetic resonance imaging [9,10], DNA separation [11], drug delivery [12,13], and MFH [6,[14][15][16]. In MFH, when the MNPs are exposed to an alternating magnetic field (AMF), the heating is due to the Neel-Brown relaxation losses [17][18][19].…”

Physicochemical properties and AC magnetic field induced heating properties of solvothermally prepared thiospinel: Fe3S4 (greigite) nanoparticles

“…The bare Fe 3 S 4 MNPs exhibited a zeta potential of ∼ −12.9 ± 1.2 mV (figure 6(c)), which was not sufficient to provide adequate electrostatic stabilization in the aqueous medium. These observations were in agreement with the experimental findings earlier reported for uncoated cobalt ferrite MNPs [34] and nano-aggregates [102]. Earlier studies by Pilati et al [103], and Obaidat et al [104], reported the importance of colloidal stability of the MNP dispersions for superior AMF induced heating efficiency.…”