Strong antibacterial efficacy of titanium surfaces modified by nanotubes and silver nanoparticles

Abstract

PURPOSE OF THE STUDY Nano-structuring and nano-silver have been extensively studied for improving the antibacterial ability of implants due to their powerful antibacterial activity; however, there is no clinical application as yet. The aim of the study was to determine the antibacterial, antiadhesive and cytotoxic features of Ti6AI4V modified with nano-texturing and silver nano-particles. MATERIAL AND METHODS The nanoparticles were applied on polished and nano-textured TÍ6AI4V using sonoreduction. The surface topography, roughness, friction coefficients, hardness and elastic modulus values for prepared top layers were established. The materials were tested for antibacterial and antiadhesion activity using reference bacterial strains (Staphylococcus epidermidis CCM 7221, Staphylococcus aureus MRSA 4591, Enterococcus faecalis CCM 4224, Escherichia coli CCM 3954) and their cytocompatibility. RESULTS A strong antibacterial activity of samples treated with nano-texture and/or silver nanoparticles compared to all the tested bacterial strains at 24 hours was proven. This antibacterial activity was diminishing in relation to Staphylococcus aureus and Enterococcus faecalis at 48 and 72 hours but remained very effective against Staphylococcus epidermidis and Escherichia coli. We also demonstrated antibiofilm activity for samples treated with silver nanoparticles and nano-tubes in experiments lasting 24 and 72 hours. DISCUSSION Our main findings are in agreement with those reported in recent literature. The implant surfaces treated with nano-texture in combination with silver nanoparticles exhibit strong antibacterial and antibiofilm characteristics. Despite there is conclusive evidence of strong antibacterial functioning, why these implant modifications have not been widely applied in clinical practice remains a question. While many obstacles including legislative procedures required for clinical implementation are more or less known, it should be clearly demonstrated that this surface modification does neither harm the patient nor interfere with the long-term survivorship of the implants before their wide-range clinical application. CONCLUSIONS Surface modification of Ti6AI4V with nano-texturing and silver nanoparticles resulted in strong antibacterial and modest antibiofilm effects. Thus, our results confirmed the technological potential of nano-texturing and silver nanoparticles for the improvement of antibacterial properties of implants.