Hybrid organic-inorganic nanomaterials for applications at the biointerfaces

Abstract

In the last few years, the application of nanomaterials (NMs) as theranostic devices, which combine diagnostic and therapeutic features, has gained a tremendous interest and development. Still, the major challenge is the understanding of the many and often complex processes that occur during the interaction of biological compounds with nanomaterials, in order to modulate their responses to the fixed target. A fine development of such smart nanosystems could occur only by a critical control of chemical/physical properties of NMs at the biological interfaces. According to such premises, this thesis deals with the investigation of NMs at the biointerfaces for potential theranostic applications. Specifically, the work has been addressed to the synthesis and characterization of several inorganic and organic nanomaterials, including gold and silver nanoparticles, hydroxyapatite, graphene and graphene oxide nanosheets tailored at the surface with stimuli-responsive polymers (polyacrylate and/or polyacrylamide) or specific chemical functionalities (amine functionalisation, sulphur functionalisation). As to the biomolecular counterpart, the performed study involved proteins (ferritin and albumin), drugs (curcumin), peptides mimicking proteins of relevant biomedical interest (such as RGD - the cell adhesive sequence of several extracellular matrix proteins-, neurotrophin peptides, fragments of the vascular endothelial growth factor), artificial membranes (lipid liposomes and supported lipid bilayers), and cells (neuroblastoma, endothelial cells, retinal pigment epithelial cells). The hybrid nano-bio-interface between the chosen NMs and biomolecules was scrutinized by a multi-technique approach, which relies on various physico-chemical spectroscopic (UV-visible, FT-IR, RAMAN, X-ray photoelectron spectroscopy), microscopic (atomic force microscopy, scanning electron microscopy, transmission electron microscopy, laser scanning confocal microscopy) and spectrometric (Time-of-Flight secondary ion mass spectrometry) methods. The research methodology used was interdisciplinary as well as the performed research, also including some biological assays on cell viability, nanoparticle internalisation by cellular uptake and nanotoxicity. The obtained results suggest promising applications for further development of these smart nanosystems for theranostic purposes.