Photodynamic Eradication of Pseudomonas aeruginosa with Ru-Photosensitizers Encapsulated in Enzyme Degradable Nanocarriers.

The development of new approaches for the treatment of the increasingly antibiotic-resistant pathogen Pseudomonas aeruginosa was targeted by enhancing the effect of local antimicrobial photodynamic therapy (aPDT) using poly(ethylene glycol)- block -poly(lactic acid) (PEG 114 - block -PLA x ) nanocarriers that were loaded with a ruthenium-based photosensitizer (PS). The action of tris(1,10-phenanthroline) ruthenium (II) bis(hexafluorophosphate) (RuPhen3) encapsulated in PEG 114 - block -PLA x micelles and vesicles was shown to result in an appreciable aPDT inactivation efficiency against planktonic Pseudomonas aeruginosa . In particular, the encapsulation of the PS, its release, and the efficiency of singlet oxygen ( 1 O 2 ) generation upon irradiation with blue light were studied spectroscopically. The antimicrobial effect was analyzed with two strains of Pseudomonas aeruginosa . Compared with PS-loaded micelles, formulations of the PS-loaded vesicles showed 10 times enhanced activity with a strong photodynamic inactivation effect of at least a 4.7 log reduction against both a Pseudomonas aeruginosa lab strain and a clinical isolate collected from the lung of a cystic fibrosis (CF) patient. This work lays the foundation for the targeted eradication of Pseudomonas aeruginosa using aPDT in various medical application areas.