This study investigates the antibacterial activity and mechanism of silver nanoparticles (SNPs) against *Escherichia coli* ATCC 8739. The research focuses on the growth, permeability, and morphology of bacterial cells following treatment with SNPs. Key findings include: 1. **Antibacterial Activity**: 10 μg/ml SNPs completely inhibited the growth of 10^7 cfu/ml *E. coli* cells in liquid Mueller–Hinton medium. 2. **Mechanism of Action**: - SNPs caused the leakage of reducing sugars and proteins, leading to the inactivation of respiratory chain dehydrogenases, indicating damage to the bacterial membrane. - Transmission electron microscopy (TEM) and scanning electron microscopy (SEM) revealed severe damage to *E. coli* cells, including pits, gaps, and fragmented cell membranes when exposed to 50 μg/ml SNPs. - TEM observations showed that SNPs dissolved and dispersed membrane vesicles, disorganizing their components. 3. **Conclusion**: SNPs damage the structure of the bacterial cell membrane and inhibit the activity of membranous enzymes, ultimately leading to the death of *E. coli* bacteria. The study provides evidence that SNPs can inhibit bacterial growth and kill cells by destroying the bacterial membrane and permeability.This study investigates the antibacterial activity and mechanism of silver nanoparticles (SNPs) against *Escherichia coli* ATCC 8739. The research focuses on the growth, permeability, and morphology of bacterial cells following treatment with SNPs. Key findings include: 1. **Antibacterial Activity**: 10 μg/ml SNPs completely inhibited the growth of 10^7 cfu/ml *E. coli* cells in liquid Mueller–Hinton medium. 2. **Mechanism of Action**: - SNPs caused the leakage of reducing sugars and proteins, leading to the inactivation of respiratory chain dehydrogenases, indicating damage to the bacterial membrane. - Transmission electron microscopy (TEM) and scanning electron microscopy (SEM) revealed severe damage to *E. coli* cells, including pits, gaps, and fragmented cell membranes when exposed to 50 μg/ml SNPs. - TEM observations showed that SNPs dissolved and dispersed membrane vesicles, disorganizing their components. 3. **Conclusion**: SNPs damage the structure of the bacterial cell membrane and inhibit the activity of membranous enzymes, ultimately leading to the death of *E. coli* bacteria. The study provides evidence that SNPs can inhibit bacterial growth and kill cells by destroying the bacterial membrane and permeability.