Development and characterization of a natural polymer-based antibacterial nanocoating for silicone breast implants

Silicone breast implants are widely used for breast augmentation, reconstruction, or to correct breast deformities. However, silicone is often associated with bacterial infection and biofilm formation. This thesis aims to overcome this limitation by developing a natural polymers-based coating made of chitosan and pectin, crosslinked with genipin and loaded with antibacterial Manuka honey derivative methylglyoxal (MGO). Layer by layer (LbL) self-assembly technique was employed to design an eight-bilayer coating on PDMS substrates previously functionalized with (3-Aminopropyl)triethoxysilane (APTES) through plasma treatment in order to provide superficial charge.Different formulations with varying amounts of MGO were produced and extensively characterized, both crosslinked and non-crosslinked. The coating stability up to 24h and 48h was tested not only at physiological neutral pH values but also at slightly acidic pH, simulating the local acidification that can occur during bacterial infection. Genipin crosslinking enhanced stability at physiological pH, whereas at acidic pH, the coating remained stable without crosslinking. Superficial amine groups were quantified using the Acid Orange assay, demonstrating the success of the APTES treatment. The successful deposition of polyelectrolytes was monitored by Quartz crystal microbalance (QCM-D), obtaining the mass and thickness values of the coating. The increase in surface wettability was investigated using water angle contact (WCA). Fourier-transform infrared (FTIR) spectroscopy and X-ray photoelectron spectroscopy (XPS) were performed to analyze the chemical bonds and elemental composition of the coating. The profilometer and scanning electron microscopy (SEM) analysis were carried out to estimate superficial roughness and explore the topography of the surface, respectively. Bacterial reduction, XTT, and Live&Dead assays were performed to evaluate the bacterial properties of the coating, which showed to exert a bacteriostatic action limiting the bacterial adhesion