The master thesis investigated the in situ synthesis of silver nanoparticles (Ag NPs)
on silk using kombucha, a fermented beverage prepared with a symbiotic culture of
bacteria and yeast (SCOBY), as an eco-friendly reducing and stabilizing agent. The
synthesis was carried out in two ways: In the first approach, the silk was first treated
with fermented kombucha tea and then with a 0.2 mM AgNO3 solution, while in the
second approach, the sequence was reversed. The synthesis time was 1, 2 or 4
hours. The analyses of morphological, chemical and optical properties showed that
kombucha was effective as a reducing and stabilising agent for the green in situ
synthesis of Ag NPs on silk. The reagent sequence and the synthesis time influenced
the chemical interactions between the fibres and the Ag NPs as well as the optical
properties, while the differences in silver content between the samples were small
and statistically insignificant. Photoluminescence analysis revealed emission in the
blue–violet region, characteristic of small Ag NPs in the nanocluster size range, while
spectrophotometric measurements further confirmed changes in colour parameters
and the appearance of a pronounced surface plasmon resonance (SPR) peak at
~380 nm, which was most prominent after two hours of synthesis. The functionalized
silk samples showed complete inhibition of E. coli growth and high efficacy against S.
aureus. Based on the results of antibacterial performance, the first reagent sequence
was selected as optimal — treatment with kombucha followed by the addition of
AgNO3 solution, with a synthesis time of 2 hours. This combination maintained over
90% inhibition of E. coli growth even after ten wash cycles.
The results confirm the great potential of using kombucha for the sustainable
functionalisation of textiles, as it enables the synthesis of Ag NPs with minimal use of
chemical reagents and is a reliable and process-adaptable method suitable for
industrial applications.
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