Synthesis, physicochemical and biological characterization of layer by layer oil in water nanocapsules

Oil in water nanoemulsions (O/W NEs) represent an ideal vehicle for drug delivery thanks to their ability to dissolve large quantities of hydrophobic drugs and protect their cargo from hydrolysis and enzymatic degradation. The stabilization of O/W NEs by means of a polymer coating, obtained through the layer by layer methodology (LbL), and the polyethylene glycol (PEG) conjugation are extremely important respectively to prolong the shelf life of the product and the period of blood stream circulation. In this perspective the first part of my thesis project concerns the complete physicochemical characterization of oil in water nanoemulsions coated with a polyelectrolyte (namely secondary NE) in order to identify polymer concentration domains that are thermodynamically stable and to define the degree of stability through thermodynamic functions depending upon relevant parameters affecting the stability itself, such as type of polymer coating, droplet distance, etc. This study was very important for the build-up of optimal oil in water secondary nanoemulsions (SNE). The second part of the Ph.D. work was focused on the improvement of O/W SNEs functioning as drug delivery systems in the human body based on the development of a decoration strategy by means of two macromolecules: the PEG as a molecule that increases availability of the nanocarrier in the blood stream, and a peptide as a molecule able to target the nanocarrier to a specific district. Herein, a cell penetrating peptide (CPP) that crosses cellular membranes was chosen as a model, anyway simply removing the peptide or substituting it with a ligand of a specific cell-receptor it is possible to obtain a nanocarrier that in view of its small size (below 200 nm) can promote passive targeting to tumors through the extravasation mechanism or a nanocarrier prone to active targeting, respectively. The last part of the Ph.D. study was focused on the development of a method able to identify receptors overexpression on specific cell lines. The methodology, based on Isothermal Titration Calorimetry (ITC) coupled with confluent cell layers cultured around biocompatible templating microparticles can be very helpful to identify targets, to address drug design and selectively deliver therapeutics that can cross biological barriers.