Efficacy of Pulsed 405-nm LEDs for antimicrobial photodynamic inactivation: effects of intensity, frequency, and duty cycle

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Abstract

Objective: This study investigates possible advantages in pulsed over continuous 405-nm LED-light for bacterial inactivation and energy efficiency.
Background: Alternative non-antibiotic methods of disinfection and infection control have become of significant interest. Recent studies have demonstrated the application of systems using 405-nm light-emitting diodes for continuous disinfection of the clinical environment, and also for potential treatment of contaminated wounds.
Methods: Liquid suspensions of 103 CFU/ml populations of Staphylococcus aureus were subject to pulsed 405-nm light of different frequencies, duty cycles and intensities, and for different lengths of time.
Results: Pulsed exposures with the same average irradiance of 16 mWcm2 and varying duty cycle (25%, 50%, 75%), showed very similar performance compared with continuous exposures, with 95-98% reduction of S. aureus achieved for all duty cycles. The pulsing frequency was varied in intervals from 100 Hz - 10 kHz and appeared to have little effect on antimicrobial efficacy. However, when comparing pulsed with continuous exposure, an improvement in inactivation per unit optical energy was achieved, with results showing an increase of approximately 83% in optical efficiency.
Conclusions: These results suggest that under pulsed conditions a lower energy consumption and lower perceived brightness could be achieved, thus potentially providing improved operating conditions for medical/infection-control applications without compromising antimicrobial efficacy.
LanguageEnglish
Pages150-156
Number of pages7
JournalPhotomedicine and Laser Surgery
Volume35
Issue number3
Early online date19 Oct 2016
DOIs
Publication statusPublished - 1 Mar 2017

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Disinfection
Light emitting diodes
Infection Control
Light
Staphylococcus aureus
Energy efficiency
Luminance
Energy utilization
Suspensions
Liquids
Wounds and Injuries
Population

Keywords

  • pulsed LED-light
  • continuous LED light
  • bacterial inactivation
  • energy efficiency
  • light-emitting diode (LED)
  • disinfection
  • infection control
  • antimicrobial efficacy
  • 405-nm light

Cite this

@article{0961c2d465a24c349bad1cfb763f43be,
title = "Efficacy of Pulsed 405-nm LEDs for antimicrobial photodynamic inactivation: effects of intensity, frequency, and duty cycle",
abstract = "Objective: This study investigates possible advantages in pulsed over continuous 405-nm LED-light for bacterial inactivation and energy efficiency. Background: Alternative non-antibiotic methods of disinfection and infection control have become of significant interest. Recent studies have demonstrated the application of systems using 405-nm light-emitting diodes for continuous disinfection of the clinical environment, and also for potential treatment of contaminated wounds. Methods: Liquid suspensions of 103 CFU/ml populations of Staphylococcus aureus were subject to pulsed 405-nm light of different frequencies, duty cycles and intensities, and for different lengths of time. Results: Pulsed exposures with the same average irradiance of 16 mWcm2 and varying duty cycle (25{\%}, 50{\%}, 75{\%}), showed very similar performance compared with continuous exposures, with 95-98{\%} reduction of S. aureus achieved for all duty cycles. The pulsing frequency was varied in intervals from 100 Hz - 10 kHz and appeared to have little effect on antimicrobial efficacy. However, when comparing pulsed with continuous exposure, an improvement in inactivation per unit optical energy was achieved, with results showing an increase of approximately 83{\%} in optical efficiency. Conclusions: These results suggest that under pulsed conditions a lower energy consumption and lower perceived brightness could be achieved, thus potentially providing improved operating conditions for medical/infection-control applications without compromising antimicrobial efficacy.",
keywords = "pulsed LED-light, continuous LED light, bacterial inactivation, energy efficiency, light-emitting diode (LED), disinfection, infection control, antimicrobial efficacy, 405-nm light",
author = "Gillespie, {Jonathan B.} and Michelle MacLean and Given, {Martin J.} and Wilson, {Mark P.} and Judd, {Martin D.} and Timoshkin, {Igor V.} and MacGregor, {Scott J.}",
year = "2017",
month = "3",
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doi = "10.1089/pho.2016.4179",
language = "English",
volume = "35",
pages = "150--156",
journal = "Photomedicine and Laser Surgery",
issn = "1549-5418",
number = "3",

}

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T1 - Efficacy of Pulsed 405-nm LEDs for antimicrobial photodynamic inactivation

T2 - Photomedicine and Laser Surgery

AU - Gillespie, Jonathan B.

AU - MacLean, Michelle

AU - Given, Martin J.

AU - Wilson, Mark P.

AU - Judd, Martin D.

AU - Timoshkin, Igor V.

AU - MacGregor, Scott J.

PY - 2017/3/1

Y1 - 2017/3/1

N2 - Objective: This study investigates possible advantages in pulsed over continuous 405-nm LED-light for bacterial inactivation and energy efficiency. Background: Alternative non-antibiotic methods of disinfection and infection control have become of significant interest. Recent studies have demonstrated the application of systems using 405-nm light-emitting diodes for continuous disinfection of the clinical environment, and also for potential treatment of contaminated wounds. Methods: Liquid suspensions of 103 CFU/ml populations of Staphylococcus aureus were subject to pulsed 405-nm light of different frequencies, duty cycles and intensities, and for different lengths of time. Results: Pulsed exposures with the same average irradiance of 16 mWcm2 and varying duty cycle (25%, 50%, 75%), showed very similar performance compared with continuous exposures, with 95-98% reduction of S. aureus achieved for all duty cycles. The pulsing frequency was varied in intervals from 100 Hz - 10 kHz and appeared to have little effect on antimicrobial efficacy. However, when comparing pulsed with continuous exposure, an improvement in inactivation per unit optical energy was achieved, with results showing an increase of approximately 83% in optical efficiency. Conclusions: These results suggest that under pulsed conditions a lower energy consumption and lower perceived brightness could be achieved, thus potentially providing improved operating conditions for medical/infection-control applications without compromising antimicrobial efficacy.

AB - Objective: This study investigates possible advantages in pulsed over continuous 405-nm LED-light for bacterial inactivation and energy efficiency. Background: Alternative non-antibiotic methods of disinfection and infection control have become of significant interest. Recent studies have demonstrated the application of systems using 405-nm light-emitting diodes for continuous disinfection of the clinical environment, and also for potential treatment of contaminated wounds. Methods: Liquid suspensions of 103 CFU/ml populations of Staphylococcus aureus were subject to pulsed 405-nm light of different frequencies, duty cycles and intensities, and for different lengths of time. Results: Pulsed exposures with the same average irradiance of 16 mWcm2 and varying duty cycle (25%, 50%, 75%), showed very similar performance compared with continuous exposures, with 95-98% reduction of S. aureus achieved for all duty cycles. The pulsing frequency was varied in intervals from 100 Hz - 10 kHz and appeared to have little effect on antimicrobial efficacy. However, when comparing pulsed with continuous exposure, an improvement in inactivation per unit optical energy was achieved, with results showing an increase of approximately 83% in optical efficiency. Conclusions: These results suggest that under pulsed conditions a lower energy consumption and lower perceived brightness could be achieved, thus potentially providing improved operating conditions for medical/infection-control applications without compromising antimicrobial efficacy.

KW - pulsed LED-light

KW - continuous LED light

KW - bacterial inactivation

KW - energy efficiency

KW - light-emitting diode (LED)

KW - disinfection

KW - infection control

KW - antimicrobial efficacy

KW - 405-nm light

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