Dottorato in SCIENZE CHIMICHE

Titolo della tesi: Noble metal and polymeric nanoparticles: synthesis, characterization, properties, and applications

This Ph.D. thesis focused on the synthesis and characterization of functionalized noble metal nanoparticles (MNPs, M = Au, Ag) and methylmethacrylate-based polymeric nanoparticles (MMA-PNPs). Control of size, morphology, and properties of MNPs and MMA-PNPs was accomplished through wet chemical methods, i.e., chemical reduction and surfactant-free emulsion polymerization, respectively. The synthetic versatility allowed to functionalize the metal surfaces with mono- and bifunctional hydrophilic and hydrophobic thiols (either single or mixed). The as-prepared MNPs, in the 5-30 nm size range, were tested in nanomedicine, sensing, and biotechnology applications. Bifunctional organic or organometallic hydrophobic ligands were selected to induce MNPs self-assembly into complex structures, 2D or 3D networks that showed collective properties suitable for optoelectronic applications. Xanthene-based dyes, i.e., FITC (fluorescein isothiocyanate isomer I) and RBITC (rhodamine B isothiocyanate), were also employed to functionalize the MNPs to obtain systems with both synergistic plasmonic and fluorescence properties. Hydrophilic poly(MMA-co-DMAA) and poly(MMA-co-AA)-DTPA copolymeric nanoparticles were synthesized. The effects of co-monomers ratio, temperature, and reaction time were investigated to optimize the average size and polydispersity index of the final particles. As a proof-of-concept for bimodal imaging in cancer diagnosis, i.e., radionuclide and optical imaging, the obtained PNPs were loaded with 89Y3+ ions, as a model of β– radioisotope 90Y, by addition of an aqueous solutions of 89YCl3 at different concentrations. The imaging ability of the obtained PNPs was tested in vitro on human glioblastoma T98G cell line by clonogenic assays. These optical imaging nanoprobes were obtained by physical encapsulation of FITC dye inside the core of PNPs, and the bright fluorescence of FITC-encapsulated NPs was studied via fluorescence microscopy. Extensive characterization studies were conducted on MNPs and PNPs through conventional techniques, i.e., UV-Visible, PL, FT-IR, 1H- 13C- and 31P-NMR, XRD, SERS, PAS, DLS, and ζ-potential, supported by modern techniques such as AFM, FESEM-EDX, TEM, SAXS, XPS, MicroRaman, and XRD for their physicochemical and morphostructural characterizations.