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

Khairul Islam,Manjurul Haque,Amitra Hoq,Sheikh Manjura Hoque,Fahmeed Hyder,Arup Kumar

doi:10.3390/nano10112297

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.

Highlights

X-ray diffraction (XRD) analysis reveals the structural characterization of the MnFe2O4 nanoparticles for the determination of average particle size and phase of the nanoparticles
We see that with a RF magnetic field of amplitude 26 mT, the Specific Loss Power (SLP) in the range of 100–330 depending on the particle sizes and concentrations
The results suggested that to obtain a trade-off between higher specific loss power and Tmax, MnFe2O4 nanoparticles sizes should be in the Different characterization techniques yielded good coordination to demonstrate that CS-coated MnFe2O4 nanoparticles of different sizes undergo successful surface modifications

Summary

Introduction

The applications of nanomaterials in the biomedical field allows solving many issues such as targeted drug delivery [1,2], contrast-enhancing dye in magnetic resonance imaging (MRI) [3,4,5,6,7,8], mediators for hyperthermia applications [9,10,11,12,13,14], cell labeling and tracking [15], angiography with MRI [16,17,18], cellular transfection using magnetic fields [19], cerebral blood volume (CBV) experiments of functional MRI (fMRI) [20], drug distribution in the brain [21], and antimicrobial activity agent [22]. Surface functionalized/modified spinel ferrite nanoparticles such as MnFe2O4, MgFe2O4, CoFe2O4, ZnFe2O4, Fe3O4 are excellent mediators for cancer thermotherapy and MRI contrast agents [23,24,25,26,27]. These nanoparticles are biocompatible, biodegradable, possess high transition temperatures, and have excellent chemical stability. The co-precipitation method involves the simultaneous occurrence of nucleation at several locations and inhibits the growth mechanism Since this process requires less heat, only about 80 ◦C for ferritization reaction, particle sizes are relatively smaller than any other synthesis method

Methods

Results

Conclusion