title: Photosensitization of in vitro biofilms by toluidine blue O combined with a light-emitting diode.
abstract: In natural ecosystems, micro-organisms grow preferentially attached to surfaces, forming matrix-enclosed biofilms. The aim of this study was to determine photodestruction levels in biofilms after subjecting them to photodynamic therapy. Biofilms of Streptococcus mutans, S. sobrinus, and S. sanguinis were grown on enamel slabs for 3, 5 or 7 d. Both the number of viable micro-organisms and the concentration of water-insoluble polysaccharides were analysed, and mineral loss (DeltaZ) analyses were performed on the enamel slabs. The antimicrobial potential of toluidine blue O (0.1 mg ml(-1)), associated with 85.7 J cm(-2) of a light-emission diode, was evaluated on the viability of 5-d biofilms. Both the number of micro-organisms and the concentration of water-insoluble polysaccharide increased with the age of the biofilms. A significant reduction ( approximately 95%) in viability was observed for S. mutans and S. sobrinus biofilms following photosensitization, with a > 99.9% reduction in the viability of S. sanguinis biofilms. In conclusion, a biofilm model was shown to be suitable for studying changes in bacterial numbers and enamel mineralization and for demonstrating the potential value of photosensitization in the control of in vitro biofilms.
authors.affiliation: Dental School of Piracicaba - UNICAMP, State University of Campinas, Piracicaba, SP, Brazil 13414-900.
authors.forename: Iriana C J
authors.initials: IC
authors.lastname: Zanin
authors.forename: Maristela M
authors.initials: MM
authors.lastname: Lobo
authors.forename: Lidiany K A
authors.initials: LK
authors.lastname: Rodrigues
authors.forename: Luiz A F
authors.initials: LA
authors.lastname: Pimenta
authors.forename: José F
authors.initials: JF
authors.lastname: Höfling
authors.forename: Reginaldo B
authors.initials: RB
authors.lastname: Gonçalves
mesh_terms: D000704:Analysis of Variance; D000818:Animals; D018441:Biofilms / Q000187:drug effects* / Q000254:growth & development; D002417:Cattle; D015169:Colony Count, Microbial; D003743:Dental Enamel / Q000382:microbiology; D006244:Hardness; D050296:Microbial Viability / Q000187:drug effects; D010778:Photochemotherapy / Q000379:methods*; D017319:Photosensitizing Agents / Q000494:pharmacology*; D011135:Polysaccharides, Bacterial / Q000032:analysis; D012666:Semiconductors; D018709:Statistics, Nonparametric; D013295:Streptococcus mutans / Q000187:drug effects* / Q000378:metabolism; D013298:Streptococcus sanguis / Q000187:drug effects / Q000378:metabolism; D016986:Streptococcus sobrinus / Q000187:drug effects / Q000378:metabolism; D014048:Tolonium Chloride / Q000494:pharmacology*; D017001:Tooth Demineralization / Q000188:drug therapy / Q000382:microbiology
chemical_list: D017319:Photosensitizing Agents; D011135:Polysaccharides, Bacterial; D014048:Tolonium Chloride