• biomaterials
• electrospinning
• scaffold
• tissue engineering

Tissue Engineering is an interdisciplinary field aiming at the restoration of the function of damaged tissues and organs. The most common tissue engineering approach is based on the use of a biocompatible scaffold onto which cells are seeded, in order to develop a fully or partially functional tissue construct and implant it in the human body, at the defect site.
Various scaffolds manufacturing techniques are actually being investigated by the scientifical community and new trends are emerging due to the advancement in manufacturing technology. In particular, a technique called electrospinning is emerging as an interesting methodology for scaffold production, due to the morphological features that electrospun scaffolds possess. Electrospun meshes are in fact 2 or 3D structures which can mimic the nanosized features and the organization of the extracellular matrix of native tissues, providing a favourable environment for cell attachment and proliferation. Since the beginning of this century, an increasing amount of research articles based on electrospinning are being published every year, and new and appealing advances in the electrospinning technology are giving a significant contribution to the field of Tissue Engineering.
This PhD program, performed within the European Network of Excellence (NoE) Expertissues, has been devoted to the investigation of electrospinning and the production and characterization of scaffolds for tissue engineering.
The PhD fellowship has been carried out among three well internationally recognised laboratories, including:

-the Laboratory of Polymeric Materials for Biomedical and Environmental Applications (BIOLab) of the Department of Chemistry and Industrial Chemistry of the University of Pisa (Italy), whose head is Prof. Emo Chiellini (main site of activity)

-the Biopolymer Technology Laboratory of the Department of Chemical and Biological Engineering of Chalmers University of Technology in Gothenburg (Sweden) led by Prof. Paul Gatenholm

-the Regenerative Medicine Laboratory at the Institute of Health and Biomedical Innovation (IHBI) of Queensland University of Technology in Brisbane (Australia), led by Prof. Dietmar W. Hutmacher

Besides the introduction Chapter, reviewing the use of electrospun fibrous meshes in different fields of Tissue Engineering and Drug Delivery, this thesis includes 6 main chapters:

 Development of Advanced Technologies for Tissue Engineering Applications,
describing modification of the standard solution electrospinning apparatus at BioLab in order to optimize the manufacturing process, and the design of a roto-translating collector for the obtainment of electrospun small diameter conduits
 Biodegradable polymeric micro-nanofibers by electrospinning of polyester/polyether block copolymers,
investigating the differences in (solution) electrospun meshes morphology and mechanical properties of block copolymers with different weight ratio and molecular weight of the components
 Mechanical evaluation of electrospun meshes by uniaxial loading under scanning electron microscopy,
which is based on the use of a specific apparatus to visualize fibrous meshes through scanning electron microscopy during uniaxial tensile loading. This chapter is focused on the mechanical loading of meshes produced by solution electrospinning and from 3 different materials, highlighting differences in fibrous network behaviour based on morphological analysis
 Novel Electrospun Polyurethane/Gelatin Composite Meshes for Vascular Grafts,
that discusses a novel (solution) electrospun tubular composite produced at BioLab, made from a biomedical polyurethane (Tecoflex EG-80°) and a biopolymer (gelatin). Particular attention is devoted to the analysis of the mechanical properties in wet conditions and the endothelial cells compatibility of the tubular composite as compared to the conduit constituted by the sole polyurethane
 Melt Electrospinning and Morphological Characterization of Polycaprolactone and Polycaprolactone Copolymers,
which investigates melt electrospinning as a component of electrospinning so far not adequately explored by researchers in the field. The chapter demonstrates how melt electrospinning can succesfully produce uniform Polycaprolactone (PCL) fibrous meshes with average diameter in the micron-size, which could be employed as scaffold in Tissue Engineering. The addition of a PCL copolymer, resulting into smaller diameter fibres as compared to pure PCL, is also discussed.
 Cellular Characterization of Melt Electrospun Polycaprolactone Meshes,
in which human osteoblasts are seeded on PCL melt electrospun scaffolds and cultured up to 19 weeks. Several in-vitro assays are taken into consideration to evaluate cell attachment and proliferation, together with the deposition of mineralized matrix components and production of extracellular matrix proteins by the cells.

The seven Chapters constituting the body of this PhD program, in their final form or a modified version, have been already published or are going to be submitted for publication in journals relevant to Biomaterials & Tissue Engineering.