CTAB assisted synthesis of MnFe₂O₄@ SiO₂ nanoparticles for magnetic hyperthermia and MRI application

Magnetic fluid hyperthermia (MFH) has been proven as a promising cancer therapeutic approach in conjunction with chemotherapy or physiotherapy in patients. The research to find innovative materials with a higher specific absorption rate (SAR) to reduce the dose of magnetic nanoparticles in tumor treatment through MFH while being also adequate for Magnetic Resonance Imaging (MRI) is important. Herein, MnFe2O4 NPs were synthesized with different sizes, using NaOH or NH4OH as a reducing agent, via a green-assisted hydrothermal route. A tetraethyl orthosilicate with the assist of cetrimonium bromide was used to fabricate SiO2 @MnFe2O4 NPs. Based on the Mossbauer and XRD results an undesired amount of alpha-Fe2O3 was found in the samples synthesized with NH4OH. Concentration-dependent cellular toxicity values were evaluated by invitro 3-(4,5 dimethylthiazol-2-yl)- 2,5-diphenyltetrazolium bromide (MTT) assay on A549 cells, where bare and silica coated nanoparticles exhibited non-toxicity below 691 mu g/mL and 566 mu g/mL, respectively. The ability of bare MnFe2O4 as the MRI contrast agent was higher compared to the silica-coated sample. The heating efficiency of the ferrofluids was recorded at 128 kHz and 10 kA/m and the highest SAR value was 39 W/g for the pristine MnFe2O4 NPs, making them promising potential materials in MRI and cancer treatment.