Silver nanoparticles to enhance photodynamic action of photosensitizers

Silver nanoparticles (AgNPs) have been applied in different biomedical fields mainly due to their antimicrobial action and optical properties. Due to their photophysical features derived from localized surface plasmon resonance (LSPR), AgNPs have been explored in photodynamic treatment. This noninvasive therapeutic method is based on the use of a photosensitizer (PS), applied to the biological site, that after exposure to light at a certain wavelength, undergoes a set of photochemical reactions, production of reactive oxygen species (ROS), leading the cell to death. In this way, different studies have investigated the ability of AgNPs not only as PS but also together with other PSs to increase ROS production in the photodynamic treatment due to LSPR. Thus, this chapter aims to explore the action of AgNPs associated with photodynamic treatment of cancer cells and microorganisms, presenting studies published mostly from the last five years (2017–22). In addition, it also aims to explain the fundamentals of the photodynamic effect and the basics of the LSPR in ROS production enhancement.