Cytotoxic Effects of Ag-ZnO Bimetallic Nanoparticles Synthesized with <i>Alchemilla vulgaris</i> Extract on Colon Cancer Cell Lines HT-29 and Caco-2

Introduction: Nanoparticles (NPs) have attracted the attention of scientists working on nanotechnology. NPs have different therapeutic effects. The therapeutic applications of these NPs depend on the amount of metal in the target cell, particle size, and physicochemical properties. However, previous studies have shown that bimetallic and multimetallic NPs have excellent physicochemical properties, synergistic effects, and high functionality. Materials and Methods: In this study, Alchemilla vulgaris plant extract was used to synthesize Ag-ZnO bimetallic nanoparticles (BNPs). The Ag-ZnO BNPs produced through biosynthesis were thoroughly analyzed using UV-vis spectroscopy, STEM and EDS. [Antibacterial activity assays were conducted on both gram-negative and gram-positive bacteria, and antioxidant activity was tested using the DPPH assay. Finally, cytotoxicity on L929, HT29, and Caco = 2 cell lines was evaluated using the MTT assay]. Results: UV-vis absorption spectrum showed maximum absorption at 437 nm and a shoulder peak at 354 nm. The particle sizes of the synthesized BNPs varied from 10 to 40 nm. Ag-ZnO BNPs did not have an antibacterial effect on gram-negative Escherichia coli bacteria. Against this, Ag-ZnO BNP had antibacterial activity against two gram-positive bacteria. Enterococcus faecalis showed an inhibition zone of 11 mm and an inhibition zone of 10 mm for Staphylococcus aureus . The antioxidant activity of synthesized Ag-ZnO BNPs was confirmed by 1-diphenyl-1-2-picrylhydrazyl. It showed a maximum antioxidant activity at 4000 µg/mL with a rate of 46.68%. The cytotoxicity of Ag-ZnO BNPs on L929, HT-29, and Caco-2 cells was evaluated using an MTT (3-(4,5-Dimethylthiazol-2-yl)-2,5-Diphenyltetrazolium Bromide) assay. As a result, the Ag-ZnO BNPs showed high toxicity on HT-29 and Caco-2 cell lines. Ag-ZnO BNPs at higher concentrations killed more than 50% of cancer cells (IC 50 : 8.43 µg/mL, IC 50 : 6.48 µg/mL). Ag-ZnO BNPs are less cytotoxic in L929 cells at low doses (IC 50 : 14.15 µg/mL). Conclusion: As a result, it has been proven that Ag-ZnO BNPs have antibacterial, antioxidant, and cytotoxic effects.