We report the development of a chemotherapeutic nanoformulation made of polyvinylpyrrolidone-stabilized magnetofluorescent nanoparticles (Fl-PMNPs) loaded with anticancer drugs as a promising drug carrier homing to human breast cancer cells, primary tumors, and solid tumors. First, nanoparticle uptake and cell death were evaluated in three types of human breast cells: two metastatic cancerous MCF-7 and MDA-MB-231 cells and nontumorigenic MCF-10A cells. While Fl-PMNPs were not toxic to cells even at the highest concentrations used, Dox-loaded Fl-PMNPs showed significant potency, effectively killing the different breast cancer cells, albeit at different affinities. Interestingly and superior to free Dox, Dox-loaded Fl-PMNPs were found to be more effective in killing the metastatic cells (2- to 3-fold enhanced cytotoxicities for MDA-MB-231 compared to MCF-7), compared to the normal noncancerous MCF-10A cells (up to 8-fold), suggesting huge potentials as selective anticancer agents. Electron and live confocal microscopy imaging mechanistically confirmed that the nanoparticles were successfully endocytosed and packaged into vesicles inside the cytoplasm, where Dox is released and then translocated to the nucleus exerting its cytotoxic action and causing apoptotic cell death. Furthermore, commendable and enhanced penetration in 3D multilayered primary tumor cells derived from primary lesions as well as in patient breast tumor biopsies was observed, killing the tumor cells inside. The designed nanocarriers described here can potentially open new opportunities for breast cancer patients, especially in theranostic imaging and hyperthermia. While many prior studies have focused on targeting ligands to specific receptors to improve efficacies, we discovered that even with passive-targeted tailored delivery system enhanced toxic responses can be attained.

Simple, fast, large-scale, and cost-effective preparation of uniform controlled magnetic nanoparticles remains a major hurdle on the way towards magnetically targeted applications at realistic technical conditions. Herein, we present a unique one-pot approach that relies on simple basic hydrolyticin situcoprecipitation of inexpensive metal salts (Fe2+and Fe3+) compartmentalized by stabilizing fatty acids and aided by the presence of alkylamines. The synthesis was performed at relatively low temperatures (~80°C) without the use of high-boiling point solvents and elevated temperatures. This method allowed for the production of ultra-small, colloidal, and hydrophobically stabilized magnetite metal oxide nanoparticles readily dispersed in organic solvents. The results reveal that the obtained magnetite nanoparticles exhibit narrow size distributions, good monodispersities, high saturation magnetizations, and excellent colloidal stabilities. When the [fatty acid] : [Fe] ratio was varied, control over nanoparticle diameters within the range of 2–10 nm was achieved. The amount of fatty acid and alkylamine used during the reaction proved critical in governing morphology, dispersity, uniformity, and colloidal stability. Upon exchange with water-soluble polymers, the ultra-small sized particles become biologically relevant, with great promise for theranostic applications as imaging and magnetically targeted delivery vehicles.

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