Sviluppo di particelle core-shell piezoelettriche e bioattive tramite metodo sol-gel = Development of piezoelectric and bioactive core-shell particles via sol-gel method

As an alternative to conventional bone grafts, bone tissue engineering is an innovative approach to treat bone diseases and defects, making use of biomaterials and stimuli. In this sense, bioactivity and piezoelectricity are two important aspects which have influence on bone growth and regeneration, exploiting ions release and electrical stimulation respectively. In literature there are examples regarding the combination of a piezoelectric phase and a bioactive phase, for example through the production of two distinct particles that then are solid state mixed and blended or through the incorporation of the piezoelectric phase as a secondary phase in a matrix, in order to obtain composite scaffolds or disks. The main purpose of this thesis work is the synthesis of particles, composed by a piezoelectric core and a bioactive shell, in a single formulation and as unique starting material. The synthesis process considered is the Stober process, a sol-gel method. The experimental part of this thesis, conducted at the Department of Applied Science and Technology of the Politecnico di Torino, focused on two piezoelectric materials (Barium Titanate and Zinc Oxide) in form of powders as core and on a ternary bioactive glass shell based on tetraethyl orthosilicate (TEOS), triethyl phosphate (TEP) and calcium nitrate (tetrahydrate) (CN) as precursors. To investigate the morphology and composition of these materials, in particular the effective synthesis of the bioactive shell, a Field Emission Scanning Electron Microscope (FE-SEM) equipped with Energy Dispersive Spectroscopy (EDS) analysis was performed, to investigate the chemical composition and the functional groups of the obtained particles a Fourier Transform Infrared (FTIR) spectroscopic analysis was performed; at the end, the in vitro bioactivity test was carried out in simulated body fluid (SBF) to evaluate the bioactivity of the developed materials and thus their ability to bond in vivo with bone tissue.