Green Synthesis of Co-Zn Spinel Ferrite Nanoparticles: Magnetic and Intrinsic Antimicrobial Properties

Abstract

Spinel ferrite magnetic nanoparticles have attracted considerable attention because of their high and flexible magnetic properties and biocompatibility. In this work, a set of magnetic nanoparticles of cobalt ferrite doped with zinc was synthesized via the eco-friendly sol-gel auto-combustion method. Obtained particles displayed a room-temperature ferromagnetic behavior with tuned by chemical composition values of saturation magnetization and coercivity. The maximal values of saturation magnetization ~74 Am2/kg were found in cobalt ferrite nanoparticles with a 15–35% molar fraction of cobalt replaced by zinc ions. At the same time, the coercivity exhibited a gradually diminishing trend from ~140 to ~5 mT whereas the concentration of zinc was increased from 0 to 100%. Consequently, nanoparticles produced by the proposed method possess highly adjustable magnetic properties to satisfy the requirement of a wide range of possible applications. Further prepared nanoparticles were tested with bacterial culture to display the influence of chemical composition and magnetic structure on nanoparticles-bacterial cell interaction.

Boosting Magnetoelectric Effect in Polymer-Based Nanocomposites

“…The coercivity field (H C ) was ~1.3 kOe, saturation magnetization (M S ) was ~66 emu/g, and reduced remanence (M R /M S ) of about 0.44. More detailed characterization of the magnetic and structural properties of particles was already reported elsewhere [ 34 ]. Magnetic interparticle interactions were evaluated by measuring the remanence curves and plotting of ΔM-plots (see SI and refs.…”

“…Additionally, the Zn substituted cobalt ferrite (Zn 0.25 Co 0.75 Fe 2 O 4 , ZCFO) NPs were prepared with the same sol-gel auto-combustion method. A more detailed characterization of ZCFO NPs used here is reported earlier [ 34 ].…”

“…Since the maximal acquired field was not sufficient to fully saturate the sample, the value of saturation magnetization was extrapolated with the fitting of the high-field region using the Law of Approach to Saturation (LAS): M(H) = M S (1 − A/H − B/H 2 ) where A and B are fitting parameters [ 39 ]. The Equation (2) was applied previously to estimate M S in different ferrite nanoparticles [ 34 , 40 ].…”

“…where A and B are fitting parameters [39]. The Equation (2) was applied previously to estimate M S in different ferrite nanoparticles [34,40].…”

“…The Zn 0.25 Co 0.75 Fe 2 O 4 (ZCFO) NPs have a similar average crystal size 16 ± 2 nm (Figure S1). Substitution of diamagnetic Zn 2+ ions in the spinel structure of cobalt ferrite results in a decreased value of magnetic anisotropy (K CFO = 1.6 × 10 6 erg/cm 3 ; K ZCFO = 0.95 × 10 6 erg/cm 3 [34]) and a slightly higher value of the saturation magnetization (~74 emu/g) concerning pure CFO sample (Figure S1a). ZCFO powder sample also shows a negative value of ∆M (Figure S2b) of higher magnitude due to a larger saturation magnetization, which led to the stronger dipolar interactions.…”