Manganese Ferrite Nanoparticles (MnFe2O4): Size Dependence for Hyperthermia and Negative/Positive Contrast Enhancement in MRI

Abstract

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.

Fundamentals to Apply Magnetic Nanoparticles for Hyperthermia Therapy

“…Thus, magnetic hyperthermia is a promising technique for treating cancer compared to other heating techniques [10]. Magnetic hyperthermia involves the administration (intercellular or transcellular) of MNPs followed by the application of an alternating external magnetic field, which generates heat within the tumor area [15][16][17]. However, it should be considered that less than 1% of an intravenous administered dose reaches the tumor [18].…”

Synergistic Bacteriostatic Effect of Streptomycin-Coated Nanomagnetic Functional Oxides

“…In this, the laser beam is incident on the specimen and the variation of the scattered light is detected at a known scattering angle θ by a fast photon detector to determine the mean particle size in the nm regime. The hydrodynamic diameter of the nanoparticle is an important parameter for bacteriostatic application [14]. Figure 12 (a)-(h) shows the hydrodynamic size of all the nanoparticles which are identical to the particle size calculated using the ImageJ software from the TEM images.…”

“…The SAED pattern is showing the cubic spinel structure of the M1, M3, M5, and M7 nanoparticles belonging to the Fd3m space group as per Fig. 11(a), (c), (e), and (g) [14] which supports X-ray diffraction measurements of our previous work [47,48]. Figure 11 (b), (d), (f), and (h) displays distortion in SEAD patterns which confirmed the coating of SS on the nanoparticles [56].…”

“…There are several applications of drug-coated ferrite particles i.e. hyperthermia [3][4][5][6][7][8][9][10][11][12][13][14][15][16], brain imaging [17], targeted drug delivery [18][19][20][21][22][23][24], the contrast-enhancing dye in magnetic resonance imaging (MRI) [25][26][27][28], cell labeling and tracing [29,30], and antimicrobial agent [31][32][33]. These nanoparticles have several properties like biocompatibility, biodegradability, possess high-temperature transition, and have high chemical stability [34].…”

The Role of Nanoferrites in Bio-medical Applications

“…al. [31] explored chitosan (CS) coated MnFe 2 O 4 nanoparticles in magnetic resonance imaging and relaxivity variation with concentration was linear (Fig. 3).…”