Frontiers in Microbiology (Nov 2020)

Porphyrin-Loaded Lignin Nanoparticles Against Bacteria: A Photodynamic Antimicrobial Chemotherapy Application

  • Nidia Maldonado-Carmona,
  • Nidia Maldonado-Carmona,
  • Guillaume Marchand,
  • Nicolas Villandier,
  • Tan-Sothea Ouk,
  • Mariette M. Pereira,
  • Mário J. F. Calvete,
  • Claude Alain Calliste,
  • Andrzej Żak,
  • Andrzej Żak,
  • Marta Piksa,
  • Krzysztof J. Pawlik,
  • Katarzyna Matczyszyn,
  • Stéphanie Leroy-Lhez

DOI
https://doi.org/10.3389/fmicb.2020.606185
Journal volume & issue
Vol. 11

Abstract

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The need for alternative strategies to fight bacteria is evident from the emergence of antimicrobial resistance. To that respect, photodynamic antimicrobial chemotherapy steadily rises in bacterial eradication by using light, a photosensitizer and oxygen, which generates reactive oxygen species that may kill bacteria. Herein, we report the encapsulation of 5,10,15,20-tetrakis(4-hydroxyphenyl)-21H,23H-porphyrin into acetylated lignin water-dispersible nanoparticles (THPP@AcLi), with characterization of those systems by standard spectroscopic and microscopic techniques. We observed that THPP@AcLi retained porphyrin’s photophysical/photochemical properties, including singlet oxygen generation and fluorescence. Besides, the nanoparticles demonstrated enhanced stability on storage and light bleaching. THPP@AcLi were evaluated as photosensitizers against two Gram-negative bacteria, Escherichia coli and Pseudomonas aeruginosa, and against three Gram-positive bacteria, Staphylococcus aureus, Staphylococcus epidermidis, and Enterococcus faecalis. THPP@AcLi were able to diminish Gram-positive bacterial survival to 0.1% when exposed to low white LED light doses (4.16 J/cm2), requiring concentrations below 5 μM. Nevertheless, the obtained nanoparticles were unable to diminish the survival of Gram-negative bacteria. Through transmission electron microscopy observations, we could demonstrate that nanoparticles did not penetrate inside the bacterial cell, exerting their destructive effect on the bacterial wall; also, a high affinity between acetylated lignin nanoparticles and bacteria was observed, leading to bacterial flocculation. Altogether, these findings allow to establish a photodynamic antimicrobial chemotherapy alternative that can be used effectively against Gram-positive topic infections using the widely available natural polymeric lignin as a drug carrier. Further research, aimed to inhibit the growth and survival of Gram-negative bacteria, is likely to enhance the wideness of acetylated lignin nanoparticle applications.

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