Enhanced photodynamic elimination of antibiotic-resistant pathogens <i>via</i> iron porphyrin complex FeTPPS

Antimicrobial photodynamic therapy (aPDT) is increasingly recognized as a potential approach to address infections caused by drug-resistant bacteria. Nevertheless, the selection of photosensitizers currently available for aPDT remains limited, underscoring the importance of developing innovative and potent photosensitizers. Porphyrins are considered an ideal platform for developing efficient photosensitizers. Meanwhile, iron complexes exhibit notable photodynamic antibacterial efficacy along with favorable biocompatibility. Herein, to improve the performance of photosensitizers, the iron porphyrin complex 5,10,15,20-tetrakis(4-sulfonatophenyl)porphyrinato iron (III) (FeTPPS) is evaluated for aPDT against methicillin-resistant Staphylococcus aureus (MRSA). The results demonstrate that FeTPPS-mediated aPDT exhibits marked bactericidal effects. Mechanism analysis reveals that FeTPPS-aPDT can trigger excessive production of reactive oxygen species, disrupt the cell membranes of MRSA, and inhibit ATP production. Furthermore, FeTPPS-aPDT effectively eradicates MRSA from biofilms and degrades mature biofilms. This study provides valuable insights into the design of novel photosensitizers for aPDT.