The objective of this work is to develop and characterize polymeric nanoparticles with core–shell morphology through miniemulsion polymerization combined with seeded emulsion polymerization, aiming at the application in the treatment of vascular tumors via intravascular embolization. The synthesis of the core–shell nanocomposites was divided into two main steps: (i) Formation of the core structure, consisting of poly(methyl methacrylate)/magnetic oxide coated with oleic acid (OM-OA) via miniemulsion and (ii) shell structure produced through seeded emulsion polymerization of vinyl pivalate. Nanocomposites containing about 8 wt.% of OM-OA showed high colloidal stability, mean diameter of 216.8 nm, spherical morphology, saturation magnetization (Ms) of 4.65 emu·g−1 (57.41 emu·g−1 of Fe3O4), preserved superparamagnetic behavior and glass transition temperature (Tg) of 111.8 °C. TEM micrographs confirmed the obtaining of uniformly dispersed magnetic nanoparticles in the PMMA and that the core–shell structure was obtained by seeded emulsion with Ms of 1.35 emu·g−1 (56.25 emu·g−1 of Fe3O4) and Tg of 114.7 °C. In vitro cytotoxicity assays against murine tumor of melanoma (B16F10) and human Keratinocytes (HaCaT) cell lines were carried out showing that the core–shell magnetic polymeric materials (a core, consisting of poly(methyl methacrylate)/Fe3O4 and, a shell, formed by poly(vinyl pivalate)) presented high cell viabilities for both murine melanoma tumor cell lines, B16F10, and human keratinocyte cells, HaCaT.

Polymers containing magnetic properties play an important role in biomedical therapies, such as embolotherapy or hyperthermia, for their differentiated properties. In this work, magnetite (Fe3O4) nanoparticles were synthesized by the coprecipitation method and dispersed into a thermoplastic matrix of poly(vinyl pivalate) through an emulsion polymerization process. The main goal was the individual encapsulation of magnetite nanoparticles to improve the magnetic response of the magneto-polymeric materials using polymerizable carboxylic acids as coating agents, minimizing the leaching of nanoparticles throughout the nanocomposite formation. For this purpose, synthesized magnetite had its surface modified by acrylic acid or methacrylic acid to improve its individual encapsulation during the polymerization step, thus generating a series of magnetic nanocomposite materials containing different amounts of magnetite intended for biomedical applications. X-ray diffractometry and TEM measurements provided a mean size of approximately 8 nm for the pure magnetite nanoparticles and a spherical morphology. Acid-functionalized Fe3O4 had a size of approximately 6 nm, while the nanocomposites showed a size of approximately 7 nm. Magnetization measurement provided a saturation magnetization value of approximately 75 emu/g and confirmed superparamagnetic behavior at room temperature. DSC analysis showed a glass transition temperature of 65 °C for poly(vinyl pivalate)-based nanocomposites. The tests realized with homopolymer and magnetic composites against different cell lineages (i.e., fibroblasts, keratinocytes, and human melanoma) to evaluate the levels of cytotoxicity showed good results in the different exposure times and concentrations used, since the obtained results showed cell viability greater than 70% compared to the control group, suggesting that the synthesized materials are very promising for medical applications.