Iryna Antal

d,l-lysine functionalized Fe3O4 nanoparticles for detection of cancer cells

Amino-modified magnetic nanoparticles were prepared by direct chemisorption of biocompatible d,l-lysine (DLL) on electrostatically stabilized magnetic nanoparticles with the aim to bind specific antibodies (Ab) able to detect cancer cells. The magnetic nanoparticles prepared by coprecipitation were stabilized in an acidic medium. A full optimization study of amino modification performed by UV/Vis spectroscopy and Dynamic Light Scattering measurement (DLS) confirmed an optimal DLL/Fe3O4 weight ratio of 2. The sample was subjected to complex characterizations using different techniques such as UV/Vis, FTIR and X-ray photoelectron spectroscopies (XPS) together with transmission electron microscopy and size/zeta potential measurements. While FTIR spectroscopy, UV/Vis spectroscopy and XPS confirmed the successful amino modification of Fe3O4 nanoparticles, a characterization using a vibrating sample magnetometer (VSM) indicated superparamagnetic behavior in all the prepared samples, suggesting that the coating process did not significantly affect the size and structure of the Fe3O4 nanoparticles. Magnetic nanoparticles with the optimal DLL content were conjugated with the M75 monoclonal antibody specific to carbonic anhydrase IX (CA IX), which is considered one of the best markers of tumor hypoxia and a prognostic indicator of cancer progression. The results demonstrate that all tested cell lines survived and even proliferated in the presence of amino-modified magnetic nanoparticles. Even the tubulin cytoskeletal structure was not disrupted after the exposure of cells to surface-modified magnetic nanoparticles. In contrast, internalization of the antibody-conjugated magnetic nanoparticles led to abrogation of the formation of long and extended microtubules. Finally, the finding supports the view that the M75 antibody conjugated to nanoparticles mediates their specific uptake and intracellular accumulation and that the antibody conjugated magnetic nanoparticles can be potentially used for the selective growth inhibition of CA IX-expressing cells.

Dielectric Spectroscopy of Ferronematics Based on 6CHBT Liquid Crystal

In our study, the dielectric behaviour of the rod-like liquid crystal (6CHBT) doped with magnetic nanoparticles of spherical shape was investigated by means of dielectric spectroscopy in the frequency range from 20 Hz to 2 MHz. A low frequency dielectric dispersion in the nematic and isotropic phases of the pure liquid crystal (LC) has been assigned to the space charge polarization. After doping the host LC with the magnetic nano particles, a nearly Debye-like relaxation process was observed with the temperature dependence obeying the Arrhenius law. Considering a possible electric double layer formation on the particle surfaces, the detected relaxation process in the doped LC can be associated with the electric double layer polarization. The experimental results point out that in the measured frequency range the space charge and interfacial effects constitute the main dielectric response. Any anchoring effects were not observed and are therefore expected to appear in higher frequencies.

DSC Study of Biocompatible Magnetite Nanoparticles Coated with Polymer

Magnetic nanoparticles used in biomedicine require surface modification ensuring formation of non-toxic, biocompatible nanoparticles. Among the great variety of available biocompatible polymers, a hydrophilic polymer polyethylene glycol (PEG) that has the ability to prevent protein adsorption was chosen for coating prepared magnetite nanoparticles. The aim of this work was to use differential scanning calorimetry (DSC) for studying the adsorption of PEG of different average molecular weights and different feed weights on magnetite nanoparticles and to estimate the maximal amount of PEG adsorbed on the magnetite nanoparticles. The increasing PEG molecular weight has a tendency to the decrease in the maximal feed weight ratio of PEG to magnetite in the studied complex systems. The morphology observed by scanning electron microscopy showed that all studied systems of magnetic particles coated with PEG had almost spherical shape.