title: Synergistic interaction between wavelength of light and concentration of H₂O₂ in bactericidal activity of photolysis of H₂O₂.
abstract: The present study aimed to evaluate the interaction between wavelength of light in the range of ultra violet A-visible and concentration of H2O2 in the reaction of photolysis of H2O2 from the point of view of hydroxyl radical (·OH) generation and the bactericidal activity. Light emitting diodes (LEDs) emitting the light at wavelengths of 365, 385, 400 and 465 nm were used at an irradiance of 1000 mW/cm(2). H2O2 was used at the final concentrations of 0, 250, 500, and 1000 mM. Quantitative analysis of ·OH generated by the LED irradiation of H2O2 were performed using an electron spin resonance-spin trapping technique. In a bactericidal assay, a bacterial suspension of Staphylococcus aureus prepared in sterile physiological saline was irradiated with the LEDs. The bactericidal activity of each test condition was evaluated by viable counts. When H2O2 was irradiated with the LEDs, ·OH was generated and bacteria were killed dependently on the concentration of H2O2 and the wavelength of LED. The two-way analysis of variance revealed that the wavelength, the H2O2 concentration and their interaction significantly affected the yield of ·OH and the bactericidal activity of the photolysis of H2O2. Therefore, it is suggested that bactericidal activity of photolysis of H2O2 could be enhanced by controlling the wavelength and the concentration of H2O2, which may contributes to shortening the treatment time and/or to reducing the concentration of H2O2.
authors.affiliation: Tohoku University Graduate School of Dentistry, 4-1 Seiryo, Aoba-ku, Sendai 980-8575, Japan.
authors.forename: Toshihide
authors.initials: T
authors.lastname: Toki
authors.affiliation: Tohoku University Graduate School of Dentistry, 4-1 Seiryo, Aoba-ku, Sendai 980-8575, Japan. Electronic address: keisuke@m.tohoku.ac.jp.
authors.forename: Keisuke
authors.initials: K
authors.lastname: Nakamura
authors.affiliation: Tohoku University Graduate School of Dentistry, 4-1 Seiryo, Aoba-ku, Sendai 980-8575, Japan.
authors.forename: Michiko
authors.initials: M
authors.lastname: Kurauchi
authors.affiliation: Tohoku University Graduate School of Dentistry, 4-1 Seiryo, Aoba-ku, Sendai 980-8575, Japan.
authors.forename: Taro
authors.initials: T
authors.lastname: Kanno
authors.affiliation: Tohoku University Graduate School of Dentistry, 4-1 Seiryo, Aoba-ku, Sendai 980-8575, Japan.
authors.forename: Yusuke
authors.initials: Y
authors.lastname: Katsuda
authors.affiliation: Tohoku University Graduate School of Dentistry, 4-1 Seiryo, Aoba-ku, Sendai 980-8575, Japan.
authors.forename: Hiroyo
authors.initials: H
authors.lastname: Ikai
authors.affiliation: Tohoku University Graduate School of Dentistry, 4-1 Seiryo, Aoba-ku, Sendai 980-8575, Japan.
authors.forename: Eisei
authors.initials: E
authors.lastname: Hayashi
authors.affiliation: Tohoku University Graduate School of Dentistry, 4-1 Seiryo, Aoba-ku, Sendai 980-8575, Japan.
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Egusa
authors.affiliation: Tohoku University Graduate School of Dentistry, 4-1 Seiryo, Aoba-ku, Sendai 980-8575, Japan.
authors.forename: Keiichi
authors.initials: K
authors.lastname: Sasaki
authors.affiliation: Tohoku University Graduate School of Dentistry, 4-1 Seiryo, Aoba-ku, Sendai 980-8575, Japan.
authors.forename: Yoshimi
authors.initials: Y
authors.lastname: Niwano
mesh_terms: D000900:Anti-Bacterial Agents / Q000737:chemistry / Q000494:pharmacology; D004203:Disinfection / Q000379:methods; D004578:Electron Spin Resonance Spectroscopy; D006861:Hydrogen Peroxide / Q000737:chemistry / Q000528:radiation effects*; D017665:Hydroxyl Radical / Q000737:chemistry / Q000494:pharmacology*; D008027:Light; D008029:Lighting / Q000295:instrumentation; D050296:Microbial Viability / Q000187:drug effects* / Q000528:radiation effects*; D010782:Photolysis / Q000528:radiation effects*; D019097:Spin Trapping; D013211:Staphylococcus aureus / Q000166:cytology / Q000187:drug effects* / Q000528:radiation effects*; D013997:Time Factors
chemical_list: D000900:Anti-Bacterial Agents; D017665:Hydroxyl Radical; D006861:Hydrogen Peroxide
keywords: Bactericidal activity; Disinfection; Hydrogen peroxide; Hydroxyl radical; Photolysis; Ultraviolet A; Wavelength