Light‐driven photosensitizer uptake increases Candida albicans photodynamic inactivation

• Published in: Journal of biophotonics 2017-11, Vol.10 (11), p.1538-1546
• Main Authors: Romano, Renan A., Pratavieira, Sebastião, Silva, Ana P. da, Kurachi, Cristina, Guimarães, Francisco E. G.
• Format: Article
• Language: English
• Subjects: Biological Transport - radiation effects; Candida albicans; Candida albicans - drug effects; Candida albicans - metabolism; Candida albicans - physiology; Candida albicans - radiation effects; Cell culture; Cell death; Deactivation; Dose-Response Relationship, Radiation; Illumination; Inactivation; Light; light-driven uptake; Microbial Viability - drug effects; Microbial Viability - radiation effects; photodynamic inactivation; Photosensitizing Agents - metabolism; Photosensitizing Agents - pharmacology; porphyrin derivate (Photogem); Radiation damage; Reactive oxygen species
• ISSN: 1864-063X; 1864-0648
• DOI: 10.1002/jbio.201600309

Photodynamic Inactivation (PDI) is based on the use of a photosensitizer (PS) and light that results mainly in the production of reactive oxygen species, aiming to produce microorganism cell death. PS incubation time and light dose are key protocol parameters that influence PDI response; the correct choice of them can increase the efficiency of inactivation. The results of this study show that a minor change in the PDI protocol, namely light‐driven incubation leads to a higher photosensitizer and more uniform cell uptake inside the irradiated zone. Furthermore, as the uptake increases, the damage caused by PDI also increases. The proposed light‐driven incubation prior to the inactivation illumination dose has advantages when compared to the traditional PDI treatments since it can be more selective and effective. Using a violet light as pre‐illumination (light‐driven incubation) source and a red‐light system as PDI source, it was possible to demonstrate that when compared to the traditional protocol of dark incubation, the pre‐illuminated cell culture showed an inactivation increase of 7 log units. These in vitro results performed in Candida albicans cells may result in the introduction of a new protocol for PDI. Photosensitizer uptake can be increased by a light‐driven incubation in C. albicans cells, leading to a lower survival rate comparing with the traditional dark incubation protocol.