Titanium Dioxide Sol-Gel Coatings Containing Silver and Bioglass Particles and Their Adhesive, Antibacterial, Bioactive and Cytotoxic Properties

Metal implants used for medical purposes must have physical, chemical and biological properties suitable for their intended use. In order to obtain metal biomaterials with optimised properties, their surfaces are modified. The experimental work consisted of the preparation, characterisation and description of titanium dioxide coatings on commercial titanium. Six types of coatings were synthesised with a sol-gel method, using a basic titania sol with different concentrations and combinations of AgNO₃ dopants and bioglass. The sols were applied on a mechanically treated titanium substrate by dip-coating and the coated samples were fired. A basic in vitro bioactivity test was performed under static conditions in a simulated body fluid for 21 days to monitor the formation of bonelike hydroxyapatite. The results confirmed the presence of calcium- and phosphorus-containing precipitates for coatings containing higher concentrations of bioactive glass in combination with silver. The adhesion of the coatings to the substrate was measured by a tape test. The results confirmed the excellent adhesion of all types of the coatings to the substrate. Another measurement examined the antibacterial effects of the coatings against gram-negative Escherichia coli and gram-positive Staphylococcus epidermidis after 4 and 24 hours of interaction. The best results were obtained for coatings containing silver after 24 hours of interaction, which showed a 100 % antibacterial effect in case of both types of the bacteria. The use of both types of dopants may have affected the cytocompatibility of the coatings with the host organism and, therefore, also cytotoxicity tests were performed on the L929 and hFOB 1.19 cell lines. The results of the indirect tests with hFOB 1.19 suggested that neither of the coatings were toxic. In the contact tests with hFOB 1.19, cells were detected on the selected surfaces of the coatings.