Development of novel lanthanide-doped Nanomaterials for biomedical application

The research on nanomaterials for biomedical and technological applications is nowadays particularly flourishing thanks to the multiple interesting properties deriving from the small size of the nanoparticles. Particularly interesting are lanthanide-doped nanomaterials with peculiar luminescent properties that could be applied in several technological fields, such as energy, security and bioremediation. In the biomedical field, they could be exploited as optical imaging contrast agents, therapy agents and, by proper designs that combine multiple features, as theranostic agents. In Chapter 2, a NIR optical nanothermometer based on CaF2:Y,Nd is presented. The nanomaterial was synthesized by means of an innovative microwave-assisted hydrothermal method which produced colloidal nanoparticles directly dispersible in water. The emission of the nanomaterial was improved by exploiting the declustering effect of Y3+ doping on Nd3+ clusters by increasing the Y3+ doping percentage. The optical nanothermometry features of the nanomaterial were tested in the 20-60◦C temperature range on Nd3+ emission bands in the first and second biological windows for possible biomedical applications. In Chapter 3, the preparation and the study of protein-nanoparticle hybrid films is described. In particular, by exploiting the ability of α-synuclein to aggregate upon environmental triggering, luminescent hybrid films with AuNPs and CaF2:Yb,Er NPs were prepared. The films were then characterized by means of transmission electron microscopy (TEM) and tested for their possible application as primary luminescent thermometers by exploiting the up-conversion emission of CaF2:Yb,Er NPs. In Chapter 4 a novel synthesis for the production of directly waterdispersible and colloidally stable Ln3+-doped SrF2 NPs is reported. This synthesis exploits sodium glutamate as a capping agent to confer a positively charged surface to the nanoparticles, which is useful for possible applications in various technological fields. In Chapter 5, a novel nanocomposite for possible photodynamic therapy application based on up-converting SrF2 NPs is presented. The synthesis method presented in Chapter 4 was exploited to produce up-converting nanoparticles that were further functionalized with a photosensitizer in order to induce tumor cell death upon NIR light irradiation. The nanomaterial was thoroughly characterized from the chemical-physical point of view and tested for possible biomedical applications on living cells.