NMR as Evaluation Strategy for Cellular Uptake of Nanoparticles

Advanced nanostructured materials, such as gold nanoparticles, magnetic nanoparticles, and multifunctional materials, are nowadays used in many state-of-the-art biomedical application. However, although the engineering in this field is very advanced, there remain some fundamental problems involving the interaction mechanisms between nanostructures and cells or tissues. Here we show the potential of ¹H NMR in the investigation of the uptake of two different kinds of nanostructures, that is, maghemite and gold nanoparticles, and of a chemotherapy drug (Temozolomide) in glioblastoma tumor cells. The proposed experimental protocol provides a new way to investigate the general problem of cellular uptake for a variety of biocompatible nanostructures and drugs

Cancer cell culture.

<p>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.</p

MR Images of representative animals.

<p>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).</p

TEM of MNs.

<p>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.</p

Thermal properties of MNs in alternate magnetic field.

<p>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.</p

Susceptibility measurement.

<p>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.</p

TEM shows the internalization of chains of MNs in HT-29 cancer cells.

<p>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.</p

Histological analysis of tumors.

<p>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.</p

Spin-Phonon Coupling in Iron-Doped Ultrathin Bismuth Halide Perovskite Derivatives

Spin in semiconductors facilitates magnetically controlled optoelectronic and spintronic devices. In metal halide perovskites (MHPs), doping magnetic ions is proven to be a simple and efficient approach to introducing a spin magnetic momentum. In this work, we present a facile metal ion doping protocol through the vapor-phase metal halide insertion reaction to the chemical vapor deposition (CVD)-grown ultrathin Cs3BiBr6 perovskites. The Fe-doped bismuth halide (Fe:CBBr) perovskites demonstrate that the iron spins are successfully incorporated into the lattice, as revealed by the spin-phonon coupling below the critical temperature Tc around 50 K observed through temperature-dependent Raman spectroscopy. Furthermore, the phonons exhibit significant softening under an applied magnetic field, possibly originating from magnetostriction and spin exchange interaction. The spin-phonon coupling in Fe:CBBr potentially provides an efficient way to tune the spin and lattice parameters for halide perovskite-based spintronics