Metal Nanoparticles against Bacteria

Emerging resistance of bacteria to common antibiotics is producing serious food and health problems. So, nanoparticles (NPs) are being used as alternatives for antibiotics against bacteria. For this purpose, metal and metal oxide nanoparticles are considered an important group of materials because they possess antimicrobial properties. Nanoparticles are used in antibiotic coatings for implants and medicines to fight against infection and promote wound healing, in antibiotic delivery systems for treatment of diseases, in bacterial identification systems to facilitate diagnosis of bacteria, and in antibacterial vaccines to control bacterial infections. Although the mechanism of action of nanoparticles as antimicrobials is not yet fully understood, currently used mechanisms are oxidative stress induction, metal ion release, and nonoxidative mechanisms. It has been reported that antimicrobial effects of nanoparticles depend upon its particle size. An effective mechanism of action against bacteria can be achieved by developing numerous concurrent gene mutations in the same bacterial cell to develop antimicrobial resistance, so it is difficult for bacterial cells to become resistant to nanoparticles. Future challenges of nanoparticles as antimicrobial drugs are safety/toxicity, high drug payloads, upscaled production, smart nanocarriers, sustained release, and targeting. This chapter discusses the antibacterial mechanisms of metal nanoparticles against bacteria, factors related to its effectiveness, the efficacy of nanovaccines, and challenges to their use as antimicrobial drugs.