https://doi.org/10.15255/KUI.2025.003
Published: Kem. Ind. 74 (9-10) (2025) 395–402
Paper reference number: KUI-03/2025
Paper type: Original scientific paper
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Green Synthesis of Silver Nanoparticles Using Green Tea: Characterisation and Antibacterial Properties

D. Barbir, P. Dabić, I. Weber and A. Rakić

Abstract

In this study, silver nanoparticles were synthesised through an eco-friendly process without the use of organic or toxic solvents. The synthesis was carried out with green tea serving as both the reducing and stabilising agent, using 1 mM silver nitrate solution and distilled water as solvent. Catechins present in green tea were involved in silver ion reduction. Characterisation of the colloidal silver was conducted using UV-Vis spectrophotometry, FTIR spectroscopy, dynamic light scattering (DLS) and scanning electron microscopy (SEM). UV-Vis spectrophotometer confirmed the presence of silver nanoparticles through the observation of surface plasmon resonance, while DLS and SEM analyses were employed to assess nanoparticle size, shape, and sample uniformity. DLS analysis revealed particle distribution in colloidal silver with nanoparticle sizes ranging between 32 and 95 nm. FTIR analysis confirmed the presence of polyphenols, particularly catechins, in green tea, emphasising the role of OH groups in the reduction of silver ions and nanoparticle synthesis. SEM analysis showed that the silver nanoparticles were spherical, with an average size of 62 nm. The antibacterial efficacy of the silver nanoparticles was tested against Escherichia coli NCTC 13216 and Staphylococcus aureus ATCC 25923. The results demonstrated an antimicrobial effect of green tea-synthesised silver nanoparticles against both bacteria at specific concentrations.

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Keywords

green synthesis, silver nanoparticles, green tea, Staphylococcus aureus, Escherichia coli