Biomedical applications of ZnFe2O4 nanoparticle are preferable among all kinds of ferrites due to the compatibility of Zn2+ ions for human bodies. We have followed the soft chemical route to synthesize chitosan and PEG coated ZnFe2O4 nanoparticles and also the chitosan-coated-nanoparticles encapsulated with liposome. X-ray diffraction studies by the Mo Kα target, showed the formation of single phase spinel structure. The lattice parameter turned out to be 8.48Å and grain size ~ 4.8 nm (± 0.1 nm). Similar particle size was observed by transmission electron microscope analysis. HRTEM studies showed the distinct lattice fringes thus confirming the good crystallinity of the synthesized nanoparticles. M-H curve at room temperature showed the prepared sample was superparamagnetic in nature, which is also confirmed by the doublets of Mössbauer spectroscopy. Relaxivity values (r2) of Chitosan and PEG coated ZnFe2O4 nanoparticles are 68 and 76 mM−1s−1 respectively. In order to achieve further biocompatibility the chitosan-coated-nanoparticles were encapsulated with liposome. The r2 relaxivity was found as 54mM−1s−1. MR images obtained from the in vitro experiments based on phantoms demonstrated good contrast enhancement. Induction heating of bare and coated particles was investigated to reveal the self heating temperature rising properties of ZnFe2O4 nanoparticles.

Cobalt ferrite nanoparticle (CFN) has received attention in magnetic resonance imaging (MRI) as a promising contrast agent due to its higher saturation magnetization and magneto-crystalline anisotropy. However, the in vitro cytotoxicity of CFN has raised concern for its biomedical application as a diagnostic agent. The coating of CFN by a biocompatible polymer such as chitosan (CH) might lessen the biocompatibility concern. Therefore, in this study, we examined the applicability of chitosan-coated cobalt ferrite nanoparticle (CCN) as an MRI contrast dye and investigated its biocompatibility in vivo. Phantom MRI images revealed that the relaxivity of CCN was 121 (±8) mM–1s–1, indicating the potential of CCN as a T 2-weighted contrast agent. A single intravenous (iv) administration of CCN (10 mg/kg) improved the contrast of magnetic-resonance-imaging-based angiography (MRA) and brain-MRI in male albino Wistar rats compared to the control. Furthermore, toxicity studies dependent on dose (1–20 mg/kg) and time (1–28 days) in male albino Wistar rats confirmed the in vivo biocompatibility of CCN. The physical, hematological, biochemical, and histopathological observation assured that a single iv injection of CCN up to 20 mg/kg was well adjusted with liver, kidney, heart, and brain functions. The findings of the current study consolidate CCN as a promising candidate for MRI contrast dye.

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We synthesized manganese ferrite (MnFe2O4) nanoparticles of different sizes by varying pH during chemical co-precipitation procedure and modified their surfaces with polysaccharide chitosan (CS) to investigate characteristics of hyperthermia and magnetic resonance imaging (MRI). Structural features were analyzed by X-ray diffraction (XRD), high-resolution transmission electron microscopy (TEM), selected area diffraction (SAED) patterns, and Mössbauer spectroscopy to confirm the formation of superparamagnetic MnFe2O4 nanoparticles with a size range of 5–15 nm for pH of 9–12. The hydrodynamic sizes of nanoparticles were less than 250 nm with a polydispersity index of 0.3, whereas the zeta potentials were higher than 30 mV to ensure electrostatic repulsion for stable colloidal suspension. MRI properties at 7T demonstrated that transverse relaxation (T2) doubled as the size of CS-coated MnFe2O4 nanoparticles tripled in vitro. However, longitudinal relaxation (T1) was strongest for the smallest CS-coated MnFe2O4 nanoparticles, as revealed by in vivo positive contrast MRI angiography. Cytotoxicity assay on HeLa cells showed CS-coated MnFe2O4 nanoparticles is viable regardless of ambient pH, whereas hyperthermia studies revealed that both the maximum temperature and specific loss power obtained by alternating magnetic field exposure depended on nanoparticle size and concentration. Overall, these results reveal the exciting potential of CS-coated MnFe2O4 nanoparticles in MRI and hyperthermia studies for biomedical research.

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The paper reports the thermo-therapeutic applications of chitosan- and PEG-coated nickel ferrite (NiFe2O4) nanoparticles. In this study NiFe2O4 nanoparticles were synthesized by the co-precipitation method, tuning the particle size through heat treatment in the temperature range from 200-800 °C for 3 h. XRD and TEM analysis revealed that the the ultrafine nanoparticles were of size 2-58 nm. Crystallinity of the NiFe2O4 nanoparticles in the as-dried condition with the particle size ∼2-3 nm was confirmed from the presence of a lattice fringe in the HRTEM image. VSM measurements showed that a superparamagnetic/ferromagnetic transition occurs with increasing particle size, which was further confirmed by Mössbauer spectroscopy. The nickel ferrite nanoparticles with optimum particle size of 10 nm were then coated with materials commonly used for biomedical applications, i.e. chitosan and PEG, to form homogeneous suspensions. The hydrodynamic diameter and the polydispersity index (PDI) were analyzed by dynamic light scattering at the physiological temperature of 37 °C and found to be 187 nm and 0.21 for chitosan-coated nanoparticles and 285 nm and 0.32 for PEG-coated ones. The specific loss power of rf induction heating by the set-up for hyperthermia and r 2 relaxivity by the nuclear magnetic resonance were determined. The results of induction heating measurements showed that the temperature attained by the nanoparticles of size 10 nm and concentration of about 20 mg ml(-1) was >70 °C (for chitosan) and >64 °C (for PEG). It has been demonstrated that the required temperature for hyperthermia heating could be tuned by tuning the particle size, shape and magnetization and the concentration of solution. For other potential biomedical applications of the NiFe2O4 nanoparticle solution, e.g. magnetic resonance imaging, the NMR studies yielded the T 1 and T 2 relaxivities as 0.348 and 89 mM(-1) s(-1) respectively. The fact that the T 2 relaxivity is orders of magnitude higher than T 1 indicates that this is suitable as a T 2 contrast agent for magnetic resonance imaging.