Advances in efficacy enhancement of photosensitizer-mediated photodynamic antimicrobial chemotherapy

The fight against pathogenic microorganisms has in recent decades been met with fierce setbacks owing to the antimicrobial resistance phenomenon. Conventional antimicrobials have thus weakened in their effectiveness against microbes, calling for the development of innovative strategies to combat the emerging global health crisis. A promising therapy for filling this gap is photodynamic antimicrobial chemotherapy which destroys microorganisms by making use of the combined action of a photosensitizer, light, and oxygen. The modality inactivates a wide range of pathogens, including bacteria, fungi, protozoa, and viruses. Of greater interest in photodynamic antimicrobial chemotherapy is the ability to destroy resistant strains of microbes without encouraging selection for resistance genes, thus immensely contributing to the fight against antimicrobial resistance. Different PSs vary in their microbial inactivation efficacies. Therefore, various structural modification approaches are being adopted to improve their respective activities. In this paper, recent studies focusing on strategies employed to improve the effectiveness and efficacies of PSs used in photodynamic antimicrobial chemotherapy are reviewed.