Magnetocontrollability of Fe7C3@C superparamagnetic nanoparticles in living cells

Abstract

BackgroundA new type of superparamagnetic nanoparticles with chemical formula Fe7C3@C (MNPs) showed higher value of magnetization compared to traditionally used iron oxide-based nanoparticles as was shown in our previous studies. The in vitro biocompatibility tests demonstrated that the MNPs display high efficiency of cellular uptake and do not affect cyto-physiological parameters of cultured cells. These MNPs display effective magnetocontrollability in homogeneous liquids but their behavior in cytoplasm of living cells under the effect of magnetic field was not carefully analyzed yet.ResultsIn this work we investigated the magnetocontrollability of MNPs interacting with living cells in permanent magnetic field. It has been shown that cells were capable of capturing MNPs by upper part of the cell membrane, and from the surface of the cultivation substrate during motion process. Immunofluorescence studies using intracellular endosomal membrane marker showed that MNP agglomerates can be either located in endosomes or lying free in the cytoplasm. When attached cells were exposed to a magnetic field up to 0.15 T, the MNPs acquired magnetic moment and the displacement of incorporated MNP agglomerates in the direction of the magnet was observed. Weakly attached or non-attached cells, such as cells in mitosis or after cytoskeleton damaging treatments moved towards the magnet. During long time cultivation of cells with MNPs in a magnetic field gradual clearing of cells from MNPs was observed. It was the result of removing MNPs from the surface of the cell agglomerates discarded in the process of exocytosis.ConclusionsOur data allow us to conclude for the first time that the magnetic properties of the MNPs are sufficient for successful manipulation with MNP agglomerates both at the intracellular level, and within the whole cell. The structure of the outer shells of the MNPs allows firmly associate different types of biological molecules with them. This creates prospects for the use of such complexes for targeted delivery and selective removal of selected biological molecules from living cells.Electronic supplementary materialThe online version of this article (doi:10.1186/s12951-016-0219-4) contains supplementary material, which is available to authorized users.

Long-term live cells observation of internalized fluorescent Fe@C nanoparticles in constant magnetic field

“…The first step in this direction would be studies of fine details of intracellular routes of internalized MNPs. The approaches used in our previous works allowed us to analyze the dynamics of MNPs interaction with the cells in general, starting from their adhesion to the plasma membrane and interaction with intracellular membrane organelles to the point of their exit from the cell (endocytosis–exocytosis cycle) [17, 18]. However, some TEM observations showing localization of MNPs aggregates in the cytoplasm without any connection with membranes allowed us to suggest that the picture of the MNPs behavior in a cell is incomplete and requires additional investigation using alternative experimental approaches.…”

Biocompatible coated magnetosome minerals with various organization and cellular interaction properties induce cytotoxicity towards RG-2 and GL-261 glioma cells in the presence of an alternating magnetic field

“…For MC, internalization may be influenced both by the presence of a negative charge at nanoparticle surface and by the organization in chains of the nanoparticles. Such properties may indeed increase the coupling between nanoparticles and the AMF and possibly favor endocytosis, a type of behavior that was previously reported for nanoparticles exposed to a non-oscillating magnetic field [ 55 ]. Whereas the efficacy of the coupling between the nanoparticles and the magnetic field was previously attributed to nanoparticle high magnetization [ 55 ], we believe that nanoparticle surface charge is another important parameter that should be considered to account for such behavior.…”

“…Such properties may indeed increase the coupling between nanoparticles and the AMF and possibly favor endocytosis, a type of behavior that was previously reported for nanoparticles exposed to a non-oscillating magnetic field [ 55 ]. Whereas the efficacy of the coupling between the nanoparticles and the magnetic field was previously attributed to nanoparticle high magnetization [ 55 ], we believe that nanoparticle surface charge is another important parameter that should be considered to account for such behavior. Most interestingly, M-PEI, which are highly internalized even without AMF, possibly due to the presence of a positively charged transfecting agent (PEI) at magnetosome surface [ 52 ], seem to be expelled from cells, following AMF application, possibly through exocytosis [ 56 ].…”

New superparamagnetic fluorescent Fe@C-C5ON2H10-Alexa Fluor 647 nanoparticles for biological applications

“…NPs concentration in the culture medium was 20 µg/ml. After 24 h of co-cultivation, a permanent commercial NdFeB magnet (cube with 5 mm edge length, magnetic field of 0.15 T), protected by gold shell, was placed in Petri dish [4]. Cells were observed at such conditions for 16-24 h using time-lapse confocal microscopy.…”

“…The influence of shape, size, composition, modifications and magnetic properties of NPs in living cells is being actively explored. Superparamagnetic NPs with chemical formula Fe 7 C 3 @C were previously obtained by us at high pressure and temperature and investigated by physico-chemical and biological methods [1][2][3][4].…”