Ion Release and Bactericidal Activity of Ag /Tryptophan and Ag/Cu/Tryptophan Complexes in the Structure of Cotton Tissue

The work quantitatively studied the leaching into water of Ag and Cu ions, from Ag and Ag/Cu nanoparticles (NPs) fixed on the surface of bactericidal tissues -cotton fabrics (cf) in the form of complexes with tryptophan (Trp) molecules.The effect of the modification of Ag/Cu NPs in cotton tissues by Trp on their bactericidal activity is studied.Trp adsorption isotherms demonstrate an increased sorption capacity of Ag/Cu-cf compared to Ag -cf.A significant part of NPs (about 70-80 %) is desorbed from the surface of the tissue upon contact with water in the form of complexes with Trp.The release of ions from Ag-cf and Ag/Cu -cf in the absence of Trp is about 30-55%.A strong relationship between the residual amounts of NP-Trp complexes with tissue can be explained by the presence of binding sites of the modifier with the active groups of the tissue surfaceglycosidic residues, hydroxyl groups, and others in the heterogeneous structure of cotton.The bactericidal activity of tissues containing tightly bound complexes (Ag/Cu/Trp-cf and Ag/Trp-cf), with a significantly lower content of metal NPs (1-5 mg NP per 1 g of tissue) is comparable to the activity of composites without amino acid (Ag/Cu-cf and Ag-cf), (6-30 mg NPs per 1 g of tissue) in relation to a number of bacteria: E. coli, K. Pneumoniae, P. Aeruginoss, S. Aureus, E. Faecalis, C. albicans.However, after 7 days of contact with the bacterial medium, secondary bacterial growth is detected that is not observed during use Ag/Cu-cf and Agcf.The work continues in the direction of determining the optimal ratio of NP-Trp on the surface of tissue samples in terms of their biocidal action and the dynamics of release of modifiers (NPs, Trp and their complexes) from the surface of tissues in aqueous solution.