The irradiation parameters investigation of photodynamic therapy on yeast cells

Renato A. Prates; Eriques G. da Silva; Aécio M. Yamada Jr.; Luis C. Suzuki; Claudete R. Paula; Martha S. Ribeiro

doi:10.1117/12.763059

12 February 2008 The irradiation parameters investigation of photodynamic therapy on yeast cells

Renato A. Prates, Eriques G. da Silva, Aécio M. Yamada Jr., Luis C. Suzuki, Claudete R. Paula, Martha S. Ribeiro

Proceedings Volume 6846, Mechanisms for Low-Light Therapy III; 684606 (2008) https://doi.org/10.1117/12.763059
Event: SPIE BiOS, 2008, San Jose, California, United States

Abstract

It has been proposed that photodynamic therapy (PDT) can inactivate microbial cells. A range of photosensitizers and light sources were reported as well as different fluence parameters and dye concentrations. However, much more knowledge regarding to the role of fluences, irradiation time and irradiance are required for a better understanding of the photodynamic efficiency. The aims of this study were to investigate the role of light parameters on the photoinactivation of yeast cells, and compare cell survivors in different growing phases following PDT. To perform this study, a suspension (10⁶cfu/mL) of Candida albicans ATCC-90028 was used in log and stationary-phase. Three irradiances 100mW/cm², 200mW/cm² and 300mW/cm² were compared under 3min, 6min and 9min of irradiation, resulting in fluences of 18, 36, 54, 72,108 and 162J/cm². The light source used was a laser emitting at 660nm with output power of 30, 60 and 90mW. As photosensitizer, 100μΜ methylene blue was used. PDT was efficient against yeast cells (6 log reduction) in log and stationary-phase. Neither photosensitizer nor light alone presented any reduction of cell viability. The increase of irradiance and time of irradiation showed a clearly improvement of cell photoinactivation. Interestingly, the same fluences in different irradiances presented dissimilar effects on cell viability. The irradiance and time of irradiation are important in PDT efficiency. Fluence per se is not the best parameter to compare photoinativation effects on yeast cells. The growing-phases presented the same susceptibility under C. albicans photoinactivation.

Citation Download Citation

Renato A. Prates, Eriques G. da Silva, Aécio M. Yamada Jr., Luis C. Suzuki, Claudete R. Paula, and Martha S. Ribeiro "The irradiation parameters investigation of photodynamic therapy on yeast cells", Proc. SPIE 6846, Mechanisms for Low-Light Therapy III, 684606 (12 February 2008); https://doi.org/10.1117/12.763059

ACCESS THE FULL ARTICLE

INSTITUTIONAL
Select your institution to access the SPIE Digital Library.

SELECT YOUR INSTITUTION

PERSONAL
Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.

PERSONAL SIGN IN

No SPIE Account? Create one

PURCHASE THIS CONTENT

SUBSCRIBE TO DIGITAL LIBRARY

50 downloads per 1-year subscription

Members: $195

Non-members: $335 ADD TO CART

25 downloads per 1 - year subscription

Members: $145

Non-members: $250 ADD TO CART

PURCHASE SINGLE ARTICLE

Includes PDF, HTML & Video, when available