The availability of bactericidal knitted cotton fabrics by processing a biodegradable bactericidal nano composition containing nanoparticles of silver and Na-carboxymethyl starch is studied in this work. The nanocomposite based on Na-carboxymethyl starch and silver nanoparticles were successfully fixed on the surface of knitted cotton fabrics through the formation of links between carboxymethyl groups of carboxymethyl starch and nanosilver, as well as air interlacing between nano composition and material. The analysis of the change in the colour of knitted cotton fabrics after processing them with a solution of the nano composition of silver and Na-carboxymethyl starch showed the stability of the colouristic indicators of the colour during antibacterial treatment. Knitted cotton fabrics treated with the developed nano composition exhibit high antibacterial activity towards gram-positive fungal cultures of Bacillus subtilis, Staphylococcus aureus, and gram-negative Pseudomonas aeruginosa. Consistency of colour and the presence of bacteriostatic properties after repeated washing of knitted cotton fabrics confirms the stability of the antimicrobial properties of reusable fabrics.

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Changes in the color characteristics of knitted fabrics after bactericidal finishes were studied by the colorimetric method. Antibacterial activity was tested with regard to gram-negative bacterium E. coli and gram-positive bacterium S. aureus. The strongest color changes due to the presence of Ag NPs were observed on samples dyed with lighter shades, where the color difference was mainly caused by the change in lightness and brightness. After treatment with silver NPs, the colors in samples dyed with Navy K-EN and Black NN are deepened, that is, the color intensity increases many times and the reflection coefficient decreases. Due to this effect, darker color tones can be achieved using less dye. The dyed knitted fabrics modified with Ag-carboxymethyl starch (AgCMS) NPs exhibited excellent antibacterial properties regardless of the dye color used. The dyeing did not affect the antibacterial activity of fabrics modified with AgCMS nanocomposites. The research on the resistance of the dyed knitted fabrics treated with nanocomposite AgCMS solution to washing showed the preservation of a sufficiently high antimicrobial activity, slightly decreasing only after the 10th wash in a washing solution. This is proved by exceptional resistance to washing of knitted fabrics modified with AgCMS. The results of the research allow one to solve the problem of expanding the range of antibacterial products and special clothes by treating textile materials with silver and carboxymethyl starch NPs.