This review discusses the mechanisms of antibacterial action of metal nanoparticles (NPs), focusing on their production of reactive oxygen species (ROS), cation release, biomolecule damage, ATP depletion, and membrane interaction. It highlights the potential of metal NPs as novel antibiotic agents due to their ability to target multiple biomolecules simultaneously, reducing the development of antibiotic resistance. The review also examines the effects of NPs on gene and protein regulation, including transcriptomic and proteomic profiles. Key aspects include the differences in susceptibility between Gram-positive and Gram-negative bacteria, the role of cell wall structure, and the impact of NP size, shape, and charge on their antibacterial activity. Additionally, the review explores the influence of capping agents and halogen treatment on NP toxicity, as well as the mechanisms by which NPs release ions and interact with bacterial components. The chapter concludes with an analysis of the global gene and protein regulation induced by NP exposure, providing insights into the complex mechanisms underlying NP-induced bacterial killing.This review discusses the mechanisms of antibacterial action of metal nanoparticles (NPs), focusing on their production of reactive oxygen species (ROS), cation release, biomolecule damage, ATP depletion, and membrane interaction. It highlights the potential of metal NPs as novel antibiotic agents due to their ability to target multiple biomolecules simultaneously, reducing the development of antibiotic resistance. The review also examines the effects of NPs on gene and protein regulation, including transcriptomic and proteomic profiles. Key aspects include the differences in susceptibility between Gram-positive and Gram-negative bacteria, the role of cell wall structure, and the impact of NP size, shape, and charge on their antibacterial activity. Additionally, the review explores the influence of capping agents and halogen treatment on NP toxicity, as well as the mechanisms by which NPs release ions and interact with bacterial components. The chapter concludes with an analysis of the global gene and protein regulation induced by NP exposure, providing insights into the complex mechanisms underlying NP-induced bacterial killing.