Figure 1.
Panel a shows the organization of MNs in chains in the bacteria (scale bar, 500 nm). Panels b-c show that the typical conformation of chains is maintained after isolation of MNs. Scale bars: b>200 nm, c>100 nm. Panel d, X-ray microanalysis shows the iron content of the MNs.
Figure 2.
Thermal properties of MNs in alternate magnetic field.
Variation of temperature of samples containing: (a) 6.7 mg of MNs lyophilized and (b) MNs diluted in distilled water at concentration of: 3 mg/ml, 2 mg/ml, 1 mg/ml, 0.5 mg/ml exposed to an AMF of 187 kHz (23kA/m) as a function of time, measured by infrared camera.
Figure 3.
DC susceptibility measurements performed on a freeze-dried magnetosomes sample: (a) hysteresis loops at high (300 K) and low (2 K) temperature and (b) Zero Field-Cooled/Field-Cooled (ZFC/FC) curves collected at low field, H = 50 Oe.
Figure 4.
Scattered light intensity weighted magnetosomes size distribution in ultrasonicated and filtered HEPES solution; the two peaks centered at 225 nm and 40 nm are in good agreement with the size of chains of magnetosomes and single nanoparticles, respectively.
Figure 5.
The figure shows the untreated cells (a) and MNs-treated cells (b-d) observed after 24 h. Prussian Blue evidences the iron depots. Enlargement: a>50 µm, b>10 µm, c>10 µm and d>10 µm.
Figure 6.
TEM shows the internalization of chains of MNs in HT-29 cancer cells.
The chains that have penetrated in the cells are composed by 6-10 units of MNs and are positioned near the nucleus (Panel a). In Panel b, MNs are visible at cell membrane (arrows) or in the Golgi complex. Panel c shows the localization of the MNs in cytoplasmic vacuoles at high enlargement (Scale bars, a 2 µm, b 1 µm, c 120 nm, d 10 µm). Panel d shows a representative SEM image of HT-29 cancer cell (0.2 mg/ml MNs 12 h); no appreciable alterations of the surface are visible when compared to controls.
Figure 7.
MTT assay on HT-29 cells after uptake with MNs.
MTT assay shows a negligible cytotoxic effect of MNs: percent viability of cells incubated with MNs is expressed relevant to control cells.
Figure 8.
MR Images of representative animals.
A) MRI Upper line: animal treated with MNs injection; images acquired before MNs injection (a), 24 h (b), one week (c) and two weeks (d) after MNs injection. Second line: animal treated with MNs injection with AMF; images acquired before MNs injection (e), 24 h (f), one week (g) and two weeks (h) after MNs injection. Magnetosomes are injected in tumor mass and MRI allows the detection of injection sites (white stars). B) animal treated with AMF; images acquired before 24 h (i), one week (l) and two weeks (m) after treatment. Control animal not treated with MNs and AMF; images acquired after two weeks (n).
Figure 9.
Histological analysis of tumors.
In the Panel A-C histology of tumor of the experimental group is showed. Injection site is showed in Panel A while in Panel B the living tumor area is illustrated. In the Panel C injured tumor area is showed. In Panel E-F histology of first subgroup of the control group is presented. In Panel G-I histology of second subgroup of the control group is presented and in the Panel L-N is showed the third subgroup of the control group. The presence of MNs depots is detectable in injection sites (A). MNs are capable to migrate and spread in tumor tissue causing the formation of fibrotic and necrotic areas (B, C). Scale bars, A-C 60 µm, D-E 300 µm, F and G 120 µm, H-I 60 µm, I 300 µm, M 120 µm, N 60 µm. Legend: m = MNs, n = necrosis and t = tumor.