Antimicrobial Photodynamic Therapy in the Colon: Delivering a Light Punch to the Guts?
Article first published online: 12 APR 2011
© 2011 The Authors. Photochemistry and Photobiology © 2011 The American Society of Photobiology
Photochemistry and Photobiology
Volume 87, Issue 4, pages 754–756, July/August 2011
How to Cite
Wainwright, M., Dai, T. and Hamblin, M. R. (2011), Antimicrobial Photodynamic Therapy in the Colon: Delivering a Light Punch to the Guts?. Photochemistry and Photobiology, 87: 754–756. doi: 10.1111/j.1751-1097.2011.00925.x
- Issue published online: 18 JUL 2011
- Article first published online: 12 APR 2011
- Accepted manuscript online: 19 MAR 2011 05:40AM EST
- Received 2 March 2011, accepted 10 March 2011
A paper in this issue of Photochemistry and Photobiology by Cassidy et al. describes the use of a sophisticated drug delivery vehicle prepared by the hot melt extrusion process to deliver photosensitizers to the colon. The smart vehicle protects its cargo through the acidic environment of the stomach but releases the active photosensitizers in the higher pH and anaerobic environment of the colon. The goal is to use photodynamic therapy (PDT) to destroy pathogenic microorganisms that can cause disease when they grow out of control in the colon. Since the colon is an environment with a low oxygen concentration the investigators also used tetrachlorodecaoxide, an oxygen donor to boost the available oxygen concentration. The paper reports results with Enterococcus faecalis and Bacteroides fragilis but the real medical problem demanding to be solved is Clostridium difficile that can cause intractable drug-resistant infections after antibiotic use. There still remain barriers to implementing this strategy in vivo, including light delivery to the upper colon, oxygen availability and optimizing the selectivity of photosensitizers for bacteria over colon epithelial cells. Nevertheless, this highly innovative paper lays the ground for the study of an entirely new and significant application for antimicrobial PDT.