Development of a Promising Antitumor Compound Based on Rhodium(II) Succinate Associated with Iron Oxide Nanoparticles Coated with Lauric Acid/Albumin Hybrid: Synthesis, Colloidal Stability and Cytotoxic Effect in Breast Carcinoma Cells

In this study, we report the synthesis and characterization of a new rhodium(II) succinate complex (Rh₂(suc)₄) and its immobilization on lauric acid bilayer-coated maghemite nanoparticles (MGH-2L/Rh₂(suc)₄) and subsequent adsorption with bovine serum albumin (MGH-2L/Rh₂(suc)₄/BSA). Rh₂(suc)₄ has been characterized by elemental analysis, potentiometric titration, TGA, MS, FTIR and UV-Vis analysis. The maghemite phase was confirmed by XRD, and a diameter of 10 nm was obtained by Sherrer equation. The VSM experiment showed superparamagnetic properties. TEM showed nanoparticles with a spherical shape and a mean diameter of 8.5±0.4 and 9.1 ± 0.4 nm for MGH-2L/Rh₂(suc)₄ and MGH-2L/Rh₂(suc)₄/BSA, respectively. FTIR and TGA confirmed the immobilization of Rh₂(suc)₄ and bovine serum albumin adsorption on superparamagnetic iron oxide. Hydrodynamic size (D_H) and zeta potential (ζ) measurements were made in aqueous, NaCl and DMEM media. D_H for dispersions was lower in aqueous medium, but increased in saline and DMEM media. In aqueous and saline media, ζ was not altered for MGH-2L and MGH-2L/Rh₂(suc)₄, but was significantly lower for MGH-2L/Rh₂(suc)₄/BSA. Therefore, MGH-2L/Rh₂(suc)₄/BSA was the most stable dispersion, meaning that BSA coating prevents aggregation more than lauric acid bilayer coating. MGH-2L/Rh₂(suc)₄ and MGH-2L/Rh₂(suc)₄/BSA dispersions induced cytotoxicity in breast carcinoma (MCF-7) and fibroblast cells in culture, and this effect was higher than that exerted by free Rh₂(suc)₄ and more specific to breast carcinoma cells than to fibroblasts. Therefore, we suggest that these dispersions have an important potential for future clinical applications and, thus, they should be considered a platform to enhance Rh₂(suc)₄ cytotoxicity, specifically in breast carcinoma.