Photodynamic inactivation of ESKAPE group bacterial pathogens in planktonic and biofilm cultures using metallated porphyrin-doped conjugated polymer nanoparticles

Abstract

Photodynamic inactivation (PDI) protocols using photoactive metallated porphyrin-doped conjugated polymer nanoparticles (CPNs) and blue light were developed to eliminate multidrug-resistant pathogens. CPNs-PDI protocols using varying particle concentration and irradiation doses were tested against nine pathogenic bacterial strains including antibiotic-resistant bacteria of the ESKAPE pathogens group. Bactericidal effect was achieved in methicillin-resistant Sthaphylococus aureus strains using low light doses (9.6-14.4 J/cm2); while Gram-negative bacteria required a higher light dose (28.8 J/cm2). Bacteria-CPNs interaction was studied through flow cytometry taking advantage of the intrinsic CPNs fluorescence, demonstrating that CPNs efficiently bind to the bacterial envelope. Finally, the performance of CPNs-PDI was explored in biofilms; good antibiofilm ability and almost complete eradication were observed for S. aureus and Escherichia coli biofilms, respectively, using confocal microscopy. Overall, we demonstrated that CPNs-PDI is an efficient tool not only to kill superbugs as sessile cells but also to disrupt and eradicate biofilms of highly relevant pathogenic bacterial species.