Tailored Polymers for Advanced Biomedical Devices: Electroactive Bioadhesive Coatings for Drug Delivery and Electrospun Scaffolds for Improved Biointegration and Functionality

This PhD thesis delves into the principles governing the behaviour, synthesis, processing, and application of polymers. The first section will discuss a novel biodegradable segmented polyurethane urea that was synthesized, characterized, and processed as a biomaterial. It exhibits outstanding hydrolytic resistance against degradation, a low melting point of 55°C and exceptional adhesion after melting. Notably, its adhesion to high-energy surfaces such as glass and metal at room temperature reached 2.6 MPa. Moreover, when evaluated against porcine skin underwater at 37°C, the adhesion measured an impressive 30 kPa. These findings underscore the versatile adhesion properties of the material across different conditions and surfaces, highlighting its potential for various applications, especially in contexts involving biological interfaces. For instance, as a coating interface between metallic prostheses or implantable devices and biological tissues, to improve biological tolerance and biointegration. Consequently, poly(3,4-ethylenedioxythiophene) (PEDOT) doped with polystyrene sulfonate was integrated into the bioadhesive polyurethane urea matrix to create a conductive bioadhesive coating. It was designed for insertion into the tumour microenvironment, with the capability to deliver drugs upon the application of voltage. The resulting polymer underwent comprehensive characterization through electrochemical impedance spectroscopy, conducted in both wet and dry conditions, and cyclic voltammetry. Then, paclitaxel was incorporated in the PEDOT-doped polyurethane urea matrix and porous titanium rods were dip-coated into the loaded polymeric solution. These final devices were designed around the neurosurgical toolkit to perform a biopsy and will be supported by a cartridge during the insertion. The assessment of drug release was conducted in physiological-like conditions and the in vitro effects were evaluated using a neuroblastoma cell line (SH-SY5Y). Furthermore, the intricate relationship between the applied voltage and the efficacy of the delivered drug was investigated, unravelling crucial insights into optimizing tumour treatment strategies.The second section of this thesis is dedicated to an electrospun scaffold crafted from polybutylene succinate (PolyBS), specifically designed for tissue engineering applications. The scaffold's morphology was optimized to create a small-diameter conduit featuring interconnected micro-porosity. This design aims to facilitate cell integration, adhesion, and growth, while simultaneously preventing undesirable cellular infiltration through the graft's wall. The mechanical properties of the scaffolds were thoroughly analyzed and compared to those of native conduits. To assess cytocompatibility in vitro, the scaffolds were seeded with adult normal human dermal fibroblasts. Additionally, the haemolytic effect was evaluated following incubation with diluted whole blood. After these in vitro analyses, the in vivo effects were explored by implanting these microfibrillar scaffolds to address critical bone defects. This multifaceted investigation seeks to comprehensively understand the scaffold's performance, both in terms of mechanical properties and its interaction with biological systems, thus contributing valuable insights to tissue engineering applications.