Development of a Ta/TaN/TaNx(Ag)y/TaN nanocomposite coating system and bio-response study for biomedical applications

Abstract

TaN(Ag) composited coatings are being investigated to improve biocompatibility of different biomedical devices due to the mechanical and chemical stability of TaN and bactericidal effect of silver nanoparticles. However, controlling the size, density, shape and especially the release of silver ions (Ag) into the surrounding medium becomes a challenge, since elevated levels of Ag could be cytotoxic. The aim of this work is to design and develop a new Ta/TaN/TaNx(Ag)y/TaN coating system, deposited by unbalanced DC magnetron sputtering technique, presenting an adequate balance between biocompatibility and bactericidal effect for potential applications in biomedical field. For this purpose, four different coating systems were deposited on 316L stainless steel and silicon (100) samples applying a bias voltage of-30,-60,-90 and-120V during the deposition of the top layer of TaN to vary its density. This manufacturing strategy allowed controlling the diffusion of silver nanoparticles to the coating surface and the release kinetics of silver ions in simulated body fluid (SBF). Biologic characterization has been performed with MC3T3-E1 pre-osteoblastic cells in terms of cell adhesion and long-term differentiation. Additionally, the adhesion and biofilm formation of the bacteria Streptococcus sanguinis strain in the deposited coating systems of Ta/TaN/TaNx(Ag)y/TaN were analyzed. The results indicated an improvement of cell adhesion and differentiation of the composited coating deposited with a bias of-30V compared to other coatings. Concordantly, this coating showed the lowest bacterial adhesion and biofilm formation, representing an attractive and suitable composited material for biomedical applications.

Development of multilayer Hydroxyapatite - Ag/TiN-Ti coatings deposited by radio frequency magnetron sputtering with potential application in the biomedical field

“…7 shows the water contact angle and the surface free energy of the Ti-6Al-4V and the deposited coatings. Here, it can be observed that both the TiN coating and the substrate used have hydrophobic behavior, according to the authors of the report [38], since the contact angle was greater than 90°. On the other hand, the HA-Ag coatings showed a greater water affinity, obtaining a significant reduction in the contact angle and presenting a hydrophilic character.…”

Studying the in vitro corrosion response of nanostructured TaN coatings in Hank's physiological solution

“…In the coating procedure by RDCMS technique, the nitrogen gas reacts under the electric field and acts as an anode, with extracted atoms from the cathode surface, so the coating is produced. RDCMS technique produces constant coatings 42,43 . Indeed, the continuity seems to coat the entire surface, making the coating with no holes.…”

“…RDCMS technique produces constant coatings. 42,43 Indeed, the continuity seems to coat the entire surface, making the coating with no holes. The images indicate the presence of small cavities inside the produced coating within the specimen having a content of 5.2% P N2 /P Ar (Figure 3A).…”

Structure, morphology, adhesion and in vitro biological evaluation of antibacterial multi-layer HA-Ag/SiO2/TiN/Ti coatings obtained by RF magnetron sputtering for biomedical applications

“…Ag cytotoxicity was evaluated by MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide) assay (Roche). mMSCs with a density of 10.000/cm 2 were seeded in culture plates with cell culture medium consisting of Dulbecco's Modified Eagle Medium (Invitrogen) supplemented with 10% fetal bovine serum and 1% penicillin/streptomycin at 37 °C and 5% CO2 for 24 h. After, this medium was replaced by culture medium containing AgCl, which was added to obtain Ag + concentrations from 0.06 to 14.64 mg/L, which were defined according to results registered for the Ag release assay and some reports in the literature [14,30]. Thereupon, an incubation for 72 h was carried out.…”

“…mMSCs were seeded at a density of 5.000/cm 2 on the surface of the coatings and the substrate in cell culture medium at 37 °C and 5% CO2 for 3 and 24 h. After each culture, samples were washed, fixed and permeabilized as described in [30]. For the immunostaining procedure, samples were incubated in primary antibody anti-vinculin (Sigma) dil.…”