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.