PSI - Issue 50

E.G. Zemtsova et al. / Procedia Structural Integrity 50 (2023) 307–313 Author name / Structural Integrity Procedia 00 (2019) 000 – 000

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2. Materials and methods 2.1. TiO 2 based coating techniques by sol-gel method using dip-coating technology

A TiO 2 coating was synthesized on a Ti substrate by modifying the sol – gel method developed by us Zemtsova (2016), Arbenin (2021). Technical titanium VT1-0 10x38 mm in size was used as a substrate. Achieved roughness was <0.01 µm. The film was synthesized using a solution of absolute isopropanol, titanium tetraisopropoxide, diethanolamine, and polyethylene glycol Mw = 20000 D (PEG, Merck). The coating was obtained by the sol-gel method using dip coating technology using KSV Nima Dip Coater, Singlevessel equipment. Next, the deposited film was subjected to heat treatment on a hot plate at 400°C, which led to pore formation and partial cracking. After that, the film was extracted with boiling deionized water and dried in air at 200°C to r emove excess moisture. 2.2. Method for creating a TiO 2 /Ag coating by template electrochemical synthesis For Ag deposition, an aqueous electrolyte of the following composition was used: AgNO 3 , sulfosalicylic acid with the addition of a 25% aqueous ammonia to pH 9. For template deposition, an Elins P45X potentiostat galvanostat was used. The deposition was carried out in a polypropylene cell with stirring, where Ti substrate with a TiO 2 coating was used as a working electrode, and a silver electrode was used as a counter electrode. Based on the previous results, the Ag was deposited from solution with a pulsed current, since at direct current an extremely low repeatability of the template pattern was found without repeating the geometry of the perforations. In the work 300 cycles were made, consisting of a sequence of pulses, 1 V - 5 ms, 0.3 V - 3 ms, 2 V - 10 ms, 0 V - 65 ms. 2.3. Studies on the antibacterial activity of the TiO 2 /Ag composite coating surface During the experiment, Ti plates coated with Ag structures and Ag-free samples were studied. The samples were not subjected to additional processing, including sterilization. For the study, daily cultures of reference strains sensitive to ABP in the amount of 10*6 CFU/ml were used: Enterococcus faecalis ATCC 29812, Staphylococcus aureus ATCC 25912, Klebsiella pneumoniae ATCC 19882, Acinetobacter baumannii 987, Pseudomonas aeruginosa ATCC 27853. The following were taken as controls: 1) inoculation of a suspension of microorganisms in an amount of 10*6 CFU / ml on Muller-Hinton agar to verify the suspension contamination; 2) Ti plates without Ag coating to ascertain the negative antibacterial effect of samples on microorganisms in the absence of silver. To assess the presence/absence of microorganism growth, the quantitative growth of bacteria on a dense nutrient medium was studied after inoculation of suspensions on agar from Ag-free samples after 72 h incubation. The experiments were carried out in 2 repetitions, the results are reproducible without errors. This study was carried out in accordance with ISO 22196 "Measurement of antibacterial activity on the surface of plastics and other non-porous materials". 2.4. Characteristics of TiO 2 /Ag Composite Coating The structure and morphology of the coating were studied using a Merlin scanning electron microscope (Carl Zeiss Microscopy); an EDS attachment for a Zeiss Merlin scanning microscope was used to construct elemental maps. For XRD analysis, a Rigaku "MiniFlex II" X-ray diffractometer was used.