Silver nanoparticles (AgNPs) have shown significant antimicrobial activity against both multidrug-resistant (MDR) and non-MDR bacterial and fungal strains. Their effectiveness is influenced by physico-chemical properties such as size, shape, surface charge, concentration, and colloidal state. AgNPs exert antimicrobial effects through mechanisms including adhesion to microbial cells, penetration into cells, generation of reactive oxygen species (ROS), and modulation of signal transduction pathways. However, AgNPs can also induce cytotoxicity, genotoxicity, and inflammatory responses in human cells, raising concerns about their safety in therapeutic applications. AgNPs are more effective against Gram-negative bacteria than Gram-positive ones due to differences in cell wall structure and composition. The antimicrobial activity of AgNPs is enhanced by their ability to penetrate cell membranes, disrupt intracellular structures, and damage DNA. AgNPs also generate ROS and free radicals, leading to oxidative stress and cell death. Additionally, AgNPs can modulate signal transduction pathways, affecting bacterial growth and other cellular activities. The use of AgNPs in combination with antibiotics has shown synergistic antimicrobial effects. AgNPs can also be used as a potent antifungal agent against various fungal genera. However, the size and shape of AgNPs significantly influence their antimicrobial activity and biological effects. Smaller AgNPs with higher surface area and specific surface chemistry are more effective in targeting pathogens. The antimicrobial activity of AgNPs is also influenced by their colloidal stability, which affects their ability to interact with microbial cells and deliver therapeutic effects. AgNPs in colloidal form have shown enhanced antimicrobial potential compared to AgNPs alone. The synthesis of AgNPs using various methods, including chemical reduction, biological, and green synthesis, allows for control over their size, stability, and antibacterial activity. The mechanisms of AgNPs-induced antimicrobial activity include adhesion to cell surfaces, penetration into cells, disruption of intracellular structures, and generation of ROS. These mechanisms lead to cell death and inhibition of microbial growth. However, AgNPs can also cause oxidative stress and genotoxic effects in human cells, highlighting the need for careful evaluation of their safety and efficacy in therapeutic applications. Further research is needed to optimize the use of AgNPs in antimicrobial therapy while minimizing potential toxic effects.Silver nanoparticles (AgNPs) have shown significant antimicrobial activity against both multidrug-resistant (MDR) and non-MDR bacterial and fungal strains. Their effectiveness is influenced by physico-chemical properties such as size, shape, surface charge, concentration, and colloidal state. AgNPs exert antimicrobial effects through mechanisms including adhesion to microbial cells, penetration into cells, generation of reactive oxygen species (ROS), and modulation of signal transduction pathways. However, AgNPs can also induce cytotoxicity, genotoxicity, and inflammatory responses in human cells, raising concerns about their safety in therapeutic applications. AgNPs are more effective against Gram-negative bacteria than Gram-positive ones due to differences in cell wall structure and composition. The antimicrobial activity of AgNPs is enhanced by their ability to penetrate cell membranes, disrupt intracellular structures, and damage DNA. AgNPs also generate ROS and free radicals, leading to oxidative stress and cell death. Additionally, AgNPs can modulate signal transduction pathways, affecting bacterial growth and other cellular activities. The use of AgNPs in combination with antibiotics has shown synergistic antimicrobial effects. AgNPs can also be used as a potent antifungal agent against various fungal genera. However, the size and shape of AgNPs significantly influence their antimicrobial activity and biological effects. Smaller AgNPs with higher surface area and specific surface chemistry are more effective in targeting pathogens. The antimicrobial activity of AgNPs is also influenced by their colloidal stability, which affects their ability to interact with microbial cells and deliver therapeutic effects. AgNPs in colloidal form have shown enhanced antimicrobial potential compared to AgNPs alone. The synthesis of AgNPs using various methods, including chemical reduction, biological, and green synthesis, allows for control over their size, stability, and antibacterial activity. The mechanisms of AgNPs-induced antimicrobial activity include adhesion to cell surfaces, penetration into cells, disruption of intracellular structures, and generation of ROS. These mechanisms lead to cell death and inhibition of microbial growth. However, AgNPs can also cause oxidative stress and genotoxic effects in human cells, highlighting the need for careful evaluation of their safety and efficacy in therapeutic applications. Further research is needed to optimize the use of AgNPs in antimicrobial therapy while minimizing potential toxic effects.