br However the presence of the m carboranyl cluster surround

However, the presence of the m-carboranyl cluster surround-ing the observed MNPs core present in the glioblastoma A172 cytoplasm could not be confirmed by EELS and EFTEM elemental maps, probably because of the low levels of boron, thus only Fe was clearly detected (see S. I.). To overcome this drawback and to unambiguously prove the presence of the m-carboranyl cluster coordinated at the MNPs core, high resolution XPS and EELS spectra on the A172 dried-cells sample were done. Peaks at 189 and 133 eV in the XPS analysis, which are characteristic of B-B51 and P-O bonding, were observed and that clearly confirmed the presence of m-carboranyl phosphinate coordinated to the MNP core (Figure 5). EELS analysis on the A172 dried-cells sample also shows the B-K and PL2,3 edges present in the sample proving that the carboranylphosphinate coordinates to MNPs surface.
Cell toxicity to the ligand shell coating of 1-MNPs
Finally, the toxicity of the ligand shell coating the MNPs core (Na[1] salt) was determined in both A172 and hCMEC/D3 Filipin III in a dose–response cell viability assay. As observed for the whole 1-MNPs compound, endothelial cells were more sensitive to the Na[1] salt than the glioblastoma cells since 
Cell neutron irradiation
BNCT studies were carried out incubating A172 cells for 24 h with 1-MNPs (20 μg/mL Boron). The amount of internalized Boron measured by ICP-MS was of 133 ± 25 μg/g correspond-ing to a 10B concentration of 26 ± 5 μg/g. Using the above mentioned condition, two groups of A172 cells were irradiated for 15 min in the thermal column of the TRIGA Mark II reactor at the University of Pavia (Reactor Power 30 kW): untreated control cells and 1-MNPs-treated cells. These were further compared with the respective non-irradiated controls. The proliferation rate (Figure 7) of irradiated and 1-MNPs treated cells re-plated the day after BNCT is considerably lower than both control cells, thus demonstrating the efficacy of 1-MNPs as boron carriers for this cancer therapy. On day 6, BNCT irradiation reduced by 2.5 the number of cancer cells treated with 1-MNP when compared to non-treated cells.
Evaluation of in vivo toxicity of the 1-MNP compound in mice
We aimed at proving for the first time that the 1-MNPs were well-tolerated and did not induce major acute toxicity
Figure 4. Transmission electron microscope (TEM) image of (A) glioblastoma cells (A172) and (B) endothelial hCMEC/D3 cells showing the presence of 1-MNPs into the cytoplasm with a larger load in A172cells. Glioblastoma cells (A) were also imaged by T2-weighted MRI at 7 T in glass capillaries containing cell pellets of untreated A172 cells (1) or A172 cells incubated for 6 h with 25 or 50 μg Fe/mL 1-MNPs (2 and 3, respectively) or for 24 h with 25 or 50 μg Fe/mL NPs (4 and 5, respectively).
signs such as death, seizures or convulsions but also acute pain, distress, decreased/increased motor activity or dehy-dration by monitoring body weight before and after treatment. Briefly, mice received 80 μL of 1-MNPs intrave-nously that corresponds to 0.58 ± 0.03 mg/kg of body weight, very close to the approved dose for Feridex® in humans (0.56 mg/kg of body weight) and previously tested in other “in vivo” studies.52 Importantly, all mice survived the study period (10 days) with no major signs of toxicity. In particular, we found that the individual body weight of the 2 treated groups were comparable with the control group (naïve mice) with day to day fluctuations but without showing significant differences between groups in the body weight (p = 0.9; Figure 8, A-B). 
Discussion
The development of multifunctional hybrid nanomaterials which could be applied in multi-modal treatments to obtain more efficient drugs with diminishing secondary effects is of great interest nowadays. Thus, based on the biofunctional properties of the multifunctional hybrid nanomaterials, our aim in the present study was to prepare MNPs coated with m-carboranylphosphinate ([1]−)) to be applied as a theranostic biomaterial for cancer therapy: biocompatible agents for cell labeling used for both tracking purposes and BNCT treatments.
The present study shows that the newly synthesized nanohybrid 1-MNPs could be used to target cancer cells for tumor imaging and treatment with BNCT therapy. This technique is a highly selective
type of radiation therapy that can target tumor cells without causing radiation damage to the adjacent normal cells. Specifically, the 1-MNPs compound is taken up from culture media by glioblastoma multiform cell line A172 in a higher amount than in the endothelial cells with cell-tracking properties due to the magnetic core of 1-MNPs by showing a reduced signal on T2 weighted Magnetic Resonance Imaging (MRI). This characteristic could allow the indirect quantitative determination of boron at the target site before and during neutron irradiation becoming an advantage during cancer treatment since it allows the determination of the