Characterization and Evaluation of Antimicrobial Effects of ZnO/Ag Nanoparticles Synthesized by Milk Thistle Seed Extract (Silybum marianum): A Short Report

 The use of nanotechnology is rapidly expanding in various fields, especially in the health and pharmaceutical fields. The purpose of this study was to produce biological Zinc Oxide (ZnO) and silver (Ag) nanoparticles (NPs) using extract of milk thistle seeds and to determine their antibacterial properties.

In this laboratory study, biological NPs were synthesized using aqueous extract of milk thistle, and ZnO NPs were chemically synthesized as well. After investigating the structural properties, the antibacterial effects of the nanomaterials on Escherichia coli and Staphylococcus aureus were studied at the concentrations of 0.8, 0.4, 0.2, 0.1, 0.05 and 0 (control) mg/ml.

The size of the biologically synthesized ZnO/Ag NPs was determined (17.5 nm), which was smaller than the chemical NPs (22 nm). Due to smaller size, it could have more bioactivity. Furthermore, the presence of organic compounds in the structure of NPs was confirmed. Both types of NPs showed dose-dependent antibacterial effects. Despite high sensitivity of bacteria to the biological NPs, this difference was statistically significant only at theconcentration of 0.8 mg/ml (p<0.05).

The findings showed that biological NPs were more effective on the bacterial growth. This could be due to their smaller size and presence of active plant compounds in their structure.