Nanobiomechanical behavior of Fe₃O₄@SiO₂ and Fe₃O₄@SiO₂–NH₂ nanoparticles over HeLa cells interfaces

Abstract

In this work, the behavior of HeLa cells incubated with Magnetic Nanoparticles (MNPs) and exposed to an Alternating Magnetic Field (AMF) was tested. The membrane mechanical properties, tested by AFM, showed significant modification when the cells were exposed to both MNPs and AMF. The magnetite nanoparticles (Fe 3 O 4 ) were synthesized by a coprecipitation method, encapsulated with silica (SiO 2 ): Fe 3 O 4 @SiO 2 and functionalized with amino groups (NH 2 ): Fe 3 O 4 @SiO 2 -NH 2 by sonochemical processing at a reaction time bellow 2 h. The characterization of the 3 types of MNPs was done by X-ray diffraction (XRD), FT-IR spectroscopy, X-ray photoelectron spectroscopy (XPS) and high resolution transmission electron microscopy (HR-TEM), to define the lattice, composition and morphology of the nanocore-shells. The HeLa cells were treated with two types of MNPs: Fe 3 O 4 @SiO 2 and Fe 3 O 4 @SiO 2 -NH 2 , at a temperature of 37 ° C. The mechanical analysis, performed through Atomic Force Microscopy (AFM) indentations, provided the Young modulus and stiffness of the cells. Control HeLa cells (reference), without MNPs and without AMF, presented values of 7.1 ± 5.6 kPa for the Young modulus and 4.9 ± 0.4 nN/µm for the stiffness. The statistical analysis with p<0.001 showed significant differences between the reference and the cells exposed to MNPS and AMF. Interestingly, the treatment showing the most significant difference was AMF applied to Fe 3 O 4 @SiO 2 -NH 2 exposed HeLa cells, with YM and stiffness mean values of respectively 1.4 ± 0.6 kPa and 2.5 ± 0.4 nN/µm.