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Enhanced germicidal effects of pulsed UV-LED irradiation on biofilms.
MedLine Citation:
PMID:  20854456     Owner:  NLM     Status:  In-Process    
Abstract/OtherAbstract:
AIMS: The major objective of the study was to evaluate the enhanced germicidal effects of low-frequency pulsed ultraviolet A (UVA)-light-emitting diode (LED) on biofilms.
METHODS AND RESULTS: The germicidal effects of UVA-LED irradiation (365 nm, 0·28 mW cm(-2) , in pulsed or continuous mode) on Candida albicans or Escherichia coli biofilms were evaluated by determining colony-forming units. The morphological change of microbial cells in biofilms was observed using scanning electron microscopy. After 5-min irradiation, over 90% of viable micro-organisms in biofilms had been killed, and pulsed irradiation (1-1000 Hz) had significantly greater germicidal ability than continuous irradiation. Pulsed irradiation (100 Hz, 60 min) almost completely killed micro-organisms in biofilm (>99·9%), and 20-min irradiation greatly damaged both microbial species. Interestingly, few hyphae were found in irradiated Candida biofilms. Moreover, mannitol treatment, a scavenger of hydroxyl radicals (OH(•) ), significantly protected viable micro-organisms in biofilms from UVA-LED irradiation.
CONCLUSIONS: The study demonstrated that pulsed UVA-LED irradiation has a strong germicidal effect (maximum at 100 Hz, over 5-min irradiation) and causes the disappearance of hyphal forms of Candida.
SIGNIFICANCE AND IMPACT OF THE STUDY: This study can assist in developing a low-frequency pulsed UVA-LED system to be applied to pathogenic biofilms for disinfection.
Authors:
J Li; K Hirota; H Yumoto; T Matsuo; Y Miyake; T Ichikawa
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Publication Detail:
Type:  Journal Article     Date:  2010-09-21
Journal Detail:
Title:  Journal of applied microbiology     Volume:  109     ISSN:  1365-2672     ISO Abbreviation:  J. Appl. Microbiol.     Publication Date:  2010 Dec 
Date Detail:
Created Date:  2010-11-12     Completed Date:  -     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  9706280     Medline TA:  J Appl Microbiol     Country:  England    
Other Details:
Languages:  eng     Pagination:  2183-90     Citation Subset:  IM    
Copyright Information:
© 2010 The Authors. Journal of Applied Microbiology © 2010 The Society for Applied Microbiology.
Affiliation:
Department of Oral and Maxillofacial Prosthodontics and Oral Implantology, Institute of Health Biosciences, The University of Tokushima Graduate School, Tokushima, Japan.
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