[Strong Antibacterial Efficacy of Titanium Surfaces Modified by Nanotubes and Silver Nanoparticles]. / Silné antibakteriální vlastnosti kovového povrchu modifikovaného nanotrubicemi titanu a nanostríbrem.

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 Ti6Al4V modified with nano-texturing and silver nano-particles. MATERIAL AND METHODS The nanoparticles were applied on polished and nano-textured Ti6Al4V 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 aureusand Enterococcus faecalisat 48 and 72 hours but remained very effective against Staphylococcus epidermidisand 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 Ti6Al4V 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. Key words:prosthetic joint infection, anti-infective biomaterials, titanium alloy, silver nanoparticles, nanotubes, prevention of infection.

Cytocompatibility of implants coated with titanium nitride and zirconium nitride.

INTRODUCTION: The positive cell response to the implant material is reflected by the capacity of cells to divide, which leads to the tissue regeneration and osseointegration. Technically pure titanium and its alloys are mostly used for implant manufacturing. These alloys have the adequate mechanical, physical and biological properties; nevertheless, the superior biocompatibility of bioceramics has been proven. With the arrival of new coating techniques, surface modification of materials used for implants has become a widely investigated issue. METHODS: The paper studied properties of titanium nitride (TiN) and zirconium nitride (ZrN) coatings deposited by PVD (Physical Vapour Deposition). Coatings were applied to substrates of pure titanium, Ti6Al4V, Ti35Nb6Ta titanium alloys and CoCrMo dental alloy. Different treatments of substrate surfaces were used: polishing, etching and grit blasting. Cytocompatibility tests assessed the cell colonization and their adherence to substrates. RESULTS AND CONCLUSION: Results showed that TiN layers deposited by PVD are suitable for coating all substrates studied. The polished samples and those with TiN coating exhibited a higher cell colonization. This coating technique meets the requirements for the biocompatibility of the implanted materials; furthermore, their colour range solves the issue of red aesthetics in oral implantology as the colour of these coatings prevents titanium from showing through the gingiva. This is one the most important criteria for the aesthetic success of implant therapy (Tab. 5, Ref. 18).