Light-Activable Silver Nanoparticles for Combatting Antibiotic-Resistant Bacteria and Biofilms

Silver nanoparticles (AgNPs) are among the most widely used nanoparticulate materials for antimicrobial applications. The innate antibacterial properties of AgNPs are closely associated with the release of silver ions (Ag⁺) and the generation of reactive oxygen species (ROS). Multiple reports have elaborated on the synergistic effect against bacteria by combining photosensitizers with AgNPs (PS-AgNPs). This combination allows for the light-activated generation of Ag⁺ and ROS from PS-AgNPs. This is an efficient and controlled approach for the effective elimination of pathogens and associated biofilms. This review summarizes the design and synthetic strategies to produce PS-AgNPs reported in the literature. First, we explore multiple bacterial cell death mechanisms associated with AgNPs and possible pathways for resistance against AgNPs and Ag⁺. The next sections summarize the recent findings on the design and application of PS-AgNPs for the inactivation of resistant and non-resistant bacterial strains as well as the elimination and inhibition of biofilms. Finally, the review describes major outcomes in the field and provides a perspective on the future applications of this burgeoning area of research.