Metal and Metal-Containing Nanoparticles Applied to Photodynamic Therapy for Wound Healing

Wounds, particularly chronic wounds, represent an increasing challenge for global health systems, affecting millions of people worldwide, and are often associated with persistent infections, biofilms, and multidrug-resistant microorganisms (MDRMs). In this context, the search for effective therapeutic alternatives has driven interest in photodynamic therapy (PDT), an approach in which light-excited photosensitizers promote the generation of reactive oxygen species (ROS) with antimicrobial and wound healing properties. Although first- and second-generation organic photosensitizers are widely used, they have significant limitations, including low aqueous solubility, self-aggregation, reduced photostability, and unsatisfactory ROS quantum yields. To overcome these drawbacks, various nanotechnology-based strategies have been explored. Among them, metallic nanoparticles stand out because they serve as carriers and exhibit intrinsic photosensitizing activity, high resistance to photobleaching, and remarkable extinction coefficients, which favor efficient singlet oxygen generation. Furthermore, metals such as gold and silver can enhance the performance of organic photosensitizers through a process known as metal-enhanced singlet oxygen generation, whereas others, such as copper, zinc, manganese, and magnesium, actively participate in biochemical events associated with the inflammatory and regenerative phases of wound healing. Considering these advances, this review compiles evidence published over the past five years regarding the use of metallic or metal-containing nanoparticles in PDT for acute and chronic wounds, with an emphasis on in vivo studies. In addition, we discuss the epidemiological and pathophysiological aspects of wounds and the intrinsic wound healing and antimicrobial properties of metallic compounds, thereby providing an integrated and up-to-date perspective.