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Digital archive of theses discussed at the University of Pisa


Thesis etd-02212013-194443

Thesis type
Tesi di dottorato di ricerca
Thesis title
Polymeric Nanoparticles for the Controlled Administration of Bioactive Protein Agents
Academic discipline
Course of study
tutor Dott. Chiellini, Federica
tutor Dott. Errico, Cesare
  • Drug Delivery
  • Nanoparticles
  • Polymers
Graduation session start date
Controlled drug delivery technology represents one of the most rapidly advancing areas of science in which several fields, such as chemistry, pharmaceutical technology, and medicine are contributing to human health care. For many years, fundamental and applied investigations have focused on the development of pharmaceutical formulates allowing for maximization of the therapeutic efficacy and minimization of the adverse effects of the drugs of interest. The research activities reported in the present thesis are the results of experimental work performed at Laboratory of Polymeric Materials for Biomedical and Environmental Applications (BIOLab) of the Department of Chemistry and Industrial Chemistry of the University of Pisa and in part at Laboratory of Microbiology, School of Life Sciences, Tsinghua University (Beijing, China). The main goal of this research project was to produce Growth Factors (GFs) loaded NPs in order to obtain nanocarriers for the administration of these proteins in the treatment of ischemic diseases. Ischemic diseases remain among the most prominent health problems in the western countries. Defects in blood supply compromise tissues and organs functions causing several pathologic conditions, such as ischemic limbs and chronic ulcers. Therapeutic angiogenesis is a promising strategy for the treatment of these diseases. It is based on the utilization of angiogenic related GFs to enhance the natural healing processes in ischemic tissues. Two recombinant GFs, Vascular Endothelial Growth Factor (VEGF) and basic Fibroblast Growth Factor (bFGF) were selected for the preparations of NPs. Moreover, since it is known that platelets are a great natural source of angiogenic related GFs, the possibility to encapsulate Platelet Lysate (PL), as natural source of GFs was investigated. In these research activities two polymers, with different characteristics (biodegradable and bioerodible) were employed. Poly (lactic-co-glycolic acid) [PLGA] and Poly (methacryloylglycylglycine-OH-co-hydroxypropylmethacrylamide) [Poly (Gly-co-HPMA)] are polymeric matrices selected to carry out this project, in order to obtain nanosystems that allow respectively a fast (e.g. few days) and a slow (e.g. several weeks) drug release. Moreover, a proteic model drug, Human Serum Albumin (HSA) was encapsulated with the intention of giving a better understanding of the suitability and versatility of the methods for the encapsulation of proteic drugs. In order to improve the maintenance of bioactivity of the encapsulated GFs, Heparin sodium salt (Hp) was used as stabilizing agent in all of the NPs formulations. NPs morphology, size, surface charge and encapsulation efficiency were determined, as well as the evaluation of drug release profiles. In the perspective of a practical application in the pharmaceutical field, the NPs were submitted to in vitro biological evaluation in order to investigate the cytocompatibility and bioactivity of the prepared nanosystems.
Moreover, during six months visiting period spent at Tsinghua University the research activities was aimed at the preparation of NPs by using an innovative biosurfactant, the protein Phasin P (PhaP). PhaP is small bacteria amphiphilic protein, located on the surface of polyhydroxyalkanoates (PHAs), with the capability to non-specifically bind hydrophobic polymers. Two different polymeric materials, PLGA, and Poly (3-hydroxybutyrate-co-3-hydroxyhexanoate) (PHBHHx) were used for the NPs formulation. In order to prepare NPs endowed with targeting moieties, magnetite (Fe3O4) was loaded in the nanosystems as a physical targeting agent. This technology allows the possibility to drive NPs to a specific tissue in the body by the applications of simple external magnetic field. The prepared NPs were characterized in term of size, Z-potential and morphology.