Antibacterial properties of laser-encapsulated titanium oxide nanotubes decorated with nanosilver and covered with chitosan/Eudragit polymers

To provide antibacterial properties, the titanium samples were subjected to electrochemical oxidation in the fluoride-containing diethylene glycol-based electrolyte to create a titanium oxide nanotubular surface. Afterward, the surface was covered by sputtering with silver 5 nm film, and the tops of the nanotubes were capped using laser treatment, resulting in an appearance of silver nanoparticles (AgNPs) of around 30 nm in diameter on such a modified surface. To ensure a controlled release of the bactericidal substance, the samples were additionally coated with a pH-sensitive chitosan/Eudragit 100 coating, also exhibiting bactericidal properties. The modified titanium samples were characterized using SEM, EDS, AFM, Raman, and XPS techniques. The wettability, corrosion properties, adhesion of the coating to the substrate, the release of AgNPs into solutions simulating body fluids at different pH, and antibacterial properties were further investigated. The obtained composite coatings were hydrophilic, adjacent to the surface, and corrosion-resistant. An increase in the amount of silver released as ions or metallic particles into a simulated body fluid solution at acidic pH was observed for modified samples with the biopolymer coating after three days of exposure avoiding burst effect. The proposed modification was effective against both Gram-positive and Gram-negative bacteria.