Anatase-Gentamicin Electrophoretic Coatings on Polyurethane-Modified Titanium: Antibacterial Performance, Biocompatibility, and Drug Delivery.

Abstract

Infections, limited biocompatibility, and material degradation remain major challenges for metallic implants in biomedical applications. To address these issues, this study presents a multifunctional coating strategy for Grade 2 titanium using a base layer of segmented polyurethane (Tecoflex SG-80A), followed by the co-deposition of titanium dioxide nanoparticles and gentamicin sulfate. Corrosion polarization tests revealed enhanced passivation of polyurethane-coated surfaces with no signs of pitting corrosion. Coatings showed porous microstructures with both nanoparticles and antibiotics distributed within and along pore edges. Energy-dispersive X-ray spectroscopy (EDX) confirmed the surface presence of both components. Thermogravimetric analysis indicated loadings of 0.17 ± 0.02 mg of gentamicin and 0.30 ± 0.04 mg of TiO₂ per specimen. SEM and AFM analyses showed that over 86% of the surface was covered with gentamicin and nanoparticles. Contact angle measurements revealed a hydrophilic character (35°) for coatings containing both gentamicin and TiO₂ nanoparticles, favorable for biological interactions. Cytotoxicity assays using dental pulp mesenchymal cells and fibroblasts demonstrated no cytotoxic effects after 72 h, whereas antibacterial tests against Staphylococcus aureus and Escherichia coli indicated inhibitory effects. Gentamicin release from the coatings followed the Korsmeyer-Peppas model, suggesting a diffusion-driven profile. These results support the development of durable, biocompatible, and antibacterial coatings for titanium implants that can reduce infection risk, enhance corrosion resistance, and support tissue integration.