Development and characterization of antibacterial biomaterials for coating titanium plates

Bacterial infections and biofilm structures that may occur after implantation seriously threaten the success of implants and patient health. In this thesis study, titanium (Ti) surfaces are planned to be coated with antibacterial biomaterials in order to reduce the risk of infection on implant surfaces and increase biocompatibility. For this purpose, coating solutions were prepared using a chitosan-based biopolymer matrix incorporating silver nitrate (AgNO₃) and nano zinc oxide (nZnO), known for their antibacterial properties, along with nano hydroxyapatite (nHAp) to induce osteogenic activity. Titanium plates (1×1 cm) were chemically etched using hydrofluoric acid (HF) and nitric acid (HNO₃). Subsequently, an alkali treatment was applied to generate hydroxyl (-OH) groups on the Ti surfaces, followed by the application of APTES ((3 Aminopropyl)triethoxysilane) to introduce amino (-NH₂) groups, resulting in silanized surfaces prepared for crosslinking. The coating solutions were prepared via the sol-gel method, and Ti plates were coated using the dip-coating technique and dried at room temperature. Characterizations of the coated surfaces were performed using Fourier Transform Infrared Spectroscopy (FT-IR), Scanning Electron Microscopy (SEM), and Energy Dispersive X-ray Spectroscopy (EDS). The antibacterial effectiveness of the samples was assessed through disk diffusion and antibiofilm tests, while their biocompatibility was evaluated using cytotoxicity and wound healing assays on the L929 fibroblast cell line. FT-IR analyses confirmed the presence of (-OH) and (-NH₂) groups after APTES treatment, indicating successful surface modification. SEM and EDS results demonstrated effective adhesion of the coatings to the Ti surfaces and homogeneous distribution of the additives within the chitosan matrix. Antibacterial test results showed that samples with higher additive concentrations exhibited greater antibacterial activity, particularly highlighting the potent antibacterial effect of silver. In contrast, samples with lower additive content exhibited reduced cytotoxicity and were identified as having the highest wound healing potential. In conclusion, the developed biopolymer-based coatings demonstrated promising antibacterial and biological performance, offering a significant contribution to the development of biocompatible and infection-resistant coatings for Ti implant surfaces. KEYWORDS: Titanium, antibacterial activity, chitosan, silver nitrate, zinc oxide