Recent applications of BODIPYs in antimicrobial photodynamic therapy

Antimicrobial photodynamic therapy (aPDT) has developed in recent years as a viable alternative to conventional antibiotics for the treatment of microbial infections, even in the case of multidrug resistant hospital-borne infections. Adapted from photodynamic therapy for cancer treatment, aPDT has proven to be a highly versatile treatment option due to its robust mode of action through reactive oxygen species-mediated cell death with limited resistance mechanisms to aPDT available to pathogens. The synthetic tunability of organic photosensitisers enables the generation of reactive oxygen species (ROS) via multiple intersystem crossing pathways thus enhancing the potential of dyes such as BODIPYs for aPDT. While the introduction of heavy atoms (halides and transition metals) remains the most utilised approach for enhanced ROS generation in organic photosensitisers, the more recent development of donor-acceptor dyads that's undergo intersystem crossing via charge-transfer intermediates marks a significant leap in the advancement of materials for aPDT. Furthermore, incorporation of photosensitisers into functional materials such as polymers for immobilisation on surfaces or as drug-delivery vehicles has decreased the gap between the laboratory and ‘real-world’ applications. This review highlights recent advancements in the development of BODIPY based materials for antimicrobial applications, with a focus on the mechanisms leading to population of the triplet hypersurface, and the subsequent generation of reactive oxygen species.