Synthesis and biofunctionalization of nanoparticles for breast cancer diagnosis and treatment

The early identification of the insurgence of a malignant cancer and the selective targeting of the tumor with specific drugs are still an open frontier for cancer diagnosis and treatment. The ultimate goal is to improve the therapy efficiency and to reduce the side effects usually encountered with conventional chemotherapy. Worldwide, mammary carcinoma represents the second most recurrent type of malignant tumor in adult women and the fifth cause of death among cancer types. In the context of this thesis, I have designed and developed multifunctional hybrid nanoparticles consisting of an inorganic iron oxide core, useful as source of signal for magnetic resonance imaging (MRI), and an organic shell, including bioactive ligands for the pharmacological effect combined with specific cell targeting, and a molecular dye as fluorescence signal emitter. The nanoparticle characteristics were optimized in terms of size, morphology, surface charge, stability, fluorescence emission and capability to enhance the MRI contrast. In addition, specific biomolecular ligands based on anti-HER-2 monoclonal antibody have been developed and novel strategies for their conjugation to nanoparticles were explored. The resulting hybrid nanocomplexes were tested both in vitro and in vivo to evaluate their toxicity, endocytosis, degradation pathways, and the efficient recognition of cell-surface biomarkers. Next, these nanoparticles proved to be highly effective in selectively targeting breast cancer cells in transplanted mice bearing HER-2-positive tumors. A multifaceted bioanalytical approach, combining fluorescence, magnetic relaxivity, transmission electron microscopy, and histological experiments in vivo and ex vivo, has demonstrated that these nanoprobes prevalently accumulated at the tumor by an active targeting route. The nanoparticles were endocytosed by the tumor cells following a lysosomal pathway of degradation, while did not result in permanent damage of healthy tissues. The principal outcome of this work was the development of a versatile and reliable biotechnological platform based on finely structured, multifunctional nanosized probes useful for the interrogation of biological systems.