*2.1. Substrates*

In all our experiments, the Ti6Al4V foil (grade 5, 99.7% purity, 0.20 mm thick (Strem Chemicals, Inc., Bischheim, France), 7 mm × 7 mm pieces) was used as a substrate. Before the anodization process, the Ti6Al4V foil samples were polished with sandpaper; cleaned by ultrasonication for 15 min in acetone, ethanol, and distilled water; and dried in an argon stream. Then the samples were chemically etched in a 1:4:5 mixture of HF:HNO3:H2O for 30 s, rinsed in deionized water and dried in an argon stream. The Ti6Al4V/TNT5 systems were produced using the electrochemical oxidation method in accordance with the previously described procedures [38]. The uniform TNT5 coatings were produced on the surface of Ti6Al4V substrates using a potential of U = 5 V at room temperature (RT) and at an anodization time t = 20 min. After anodization, all the produced Ti6Al4V/TNT5 samples were washed in deionized water (10 min in an ultrasonic bath) and then their surfaces were drying in a stream of argon at RT and additionally dried at 123 ◦C. The morphology of the produced coatings was studied using a Quanta scanning electron microscope with field emission (SEM, Quanta 3D FEG, Huston, TX, USA).

#### *2.2. Chemical Vapor Deposition of Silver Nanoparticles (AgNPs)*

The Ti6Al4V and Ti6Al4V/TNT5 samples were enriched with the AgNPs using the CVD technique, under conditions given in Table 1. Ag5(O2CC2F5)5(H2O)3 has been used as a metallic silver CVD precursor. Its synthesis and physicochemical properties were earlier described [36]. The morphology of created coatings was visualized using a scanning electron microscope (Quanta 3D FEG, Huston, TX, USA). The density of the AgNPs aggregation was illustrated using energy-dispersive X-ray spectroscopy (Quantax 200 XFlash 4010, Bruker AXS, Karlsruhe, Germany)). The surface topography was examined by means of atomic force microscopy (AFM, Veeco Metrology Group (Digital Instruments, Santa Barbara, CA, USA) cooperated with NanoScope IIIa controller and MultiMode microscope) using a contactless module with a force of 20 nN in the 2 × 2 μm area.


**Table 1.** The silver nanograins CVD parameters.

CVD: chemical vapor deposition.

#### *2.3. The Wettability and Surface Free Energy of Biomaterials*

In order to evaluate how well (or how poorly) the liquid spreads on the surface of the tested biomaterials, the seated drop method was applied. The contact angle was determined using a goniometer with a drop shape analysis software (DSA 10 Krüss GmbH, Hamburg, Germany). Two liquids—distilled water (H2O) and diiodomethane (CH2I2)—were the reagents chosen to measure the contact angle. For distilled water, the volume of the drop in the contact angle measurement was 3 μL, and in the case of diiodomethane, 4 μL. The measurement was carried out immediately after the drops were deposited. In order to determine the surface free energy (SFE), mathematical calculations were made using the Owens–Wendt model [39]. The measurement with both liquids was performed three times for all tested samples.

#### *2.4. Silver Ion Release in the Body Fluid Environment*

The studies of silver ions release from the surface of Ti6Al4V/AgNPs and Ti6Al4V/TNT5/AgNPs samples were carried according to the previously used procedure [36]. The pieces of 7 mm × 7 mm samples were immersed in 15 mL of phosphate buffered saline (PBS) in a sealed bottle at a temperature 37 ◦C for 1, 2, 3, 7, 10, 14, 21, 28 and 34 days. Released concentrations of silver ions in phosphate-buffered saline (PBS) were measured by mass spectrometry with plasma ionization inductively coupled to a quadrupole analyzer using an ICP-MS 7500 CX spectrometer with an Agilent Technologies collision chamber (Agilent Technologies Inc., Tokyo, Japan).
