Evaluation of antibacterial, antioxidant, photocatalytic activities of silver-decorated TiO2 comparison green and classic capping agent

The one-pot plasma-liquid synthesis and coating of Ag NPs, capped/stabilized with different capping agents, over commercial photocatalysts TiO2 was used for preparation composite. Traditional (Alginate, Citrate, PVP, and CMC) and "green " (grape cake) stabilizers were used. The photocatalysts were characterized by SEM, UV-vis, and elemental mapping analysis. It was found that the samples exhibited an absorption peak in the visible region due to surface plasmon resonance, the reduction of the band gap was 2.7 eV and did not depend on the type of capping agent, Ag Nps. The study of the photocatalytic activity of the obtained composites (on the example of the decomposition of the antibiotic-tetracycline) under different experimental conditions showed that the type of silver nanoparticle stabilizer did not affect the photocatalytic activity of the composite. The antioxidant effect of composites was also tested on the reference radical DPPH (2,2-diphenyl-1-picrylhydrazyl). It was found that the intensity of antioxidant activity depends on the type of stabilizer. Only when using the "green " type of stabilizer is the antioxidant activity of the composite at a level of 31-70% (at 0.1-0.65 mg/ml). The antibacterial effect of composites was also tested: AgNPs supported on TiO2 showed good antibacterial activity against Gram-negative bacteria (Escherichia coli). It was found that the intensity of antimicrobial action also depends on the type of stabilizer, but in small quantities (zone of inhibition of samples within 3-5 mm) and for the "green " stabilizer, it is the highest.