Irradiation of titanium dioxide generates both singlet oxygen and superoxide anion

Konaka, Ryusei; Kasahara, Emiko; Dunlap, Walter C.; Yamamoto, Yorihiro; Chien, Kuang Chang; Inoue, Masayasu

doi:10.1016/s0891-5849(99)00050-7

Cited by 194 publications

(130 citation statements)

References 22 publications

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“…Nano-titanium dioxide increased the fungicidal effect in the erythrosine group when stimulated by blue light and also increased the generation of singlet oxygen in the group with 440 μM erythrosine stimulated by blue light. Konaka et al have reported that titanium dioxide irradiated with UV light could produce both singlet oxygen and superoxide anion [17]. This is consistent with our result that blue light may increase the effect of erythrosine dye.…”

Section: Discussionsupporting

confidence: 93%

“…This dye molecule, which was stimulated by light, transfers electrons to the conduction band of semiconductor (TiO 2 ) and then reacts with oxygen molecule on the TiO 2 surface to generate superoxide anion and hydroxyl radicals [18]. Unfortunately, in our study, we could not measure the amount of superoxide anion, partly due to the lower amount of TiO 2 compared with previous studies [17,19]. Moreover, the suitable light for stimulating TiO 2 to generate free radicals, especially superoxide anions, is not visible by UV light [20].…”

Section: Discussionmentioning

confidence: 67%

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Fungicidal effect of combined nano TiO2 with erythrosine for mediated photodynamic therapy on Candida albicans: an in vitro study

et al. 2017

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Background and objective Candida albicans is an opportunistic pathogen that can cause oral candidiasis. Antifungal drugs have been used for treatment, but resistance to these drugs has emerged in recent years. Photodynamic therapy is one of the alternative treatments. The purpose of this study was to evaluate the killing of C. albicans biofilms in photodynamic therapy in vitro by erythrosine (Ery) gel on its own or in combination with nano-titanium dioxide (TiO 2 ) stimulated by blue light (BL). Methods Four test groups were studied, namely, Ery gel at 220 and 440 μM, in the presence or absence of 1% TiO 2 + BL, and the control group. After C. albicans biofilms were prepared, a photosensitizer was applied to them for 15 min. Test groups were then activated by BL with 15 J/cm 2 energy for 1 min, and the number of CFU/mL in log 10 was compared between the test and control groups. In addition, the generation of reactive oxygen species by the effective photosensitizer was tested by electron spin resonance spectrometer (ESR) using 2,2,6,6-tetramethyl-4-piperidone and 5,5-dimethyl-1-pyrroline N-oxide. Results C. albicans survival rates were different with statistical significance across all groups by the Kruskal-Wallis test (p < 0.001). The group of 440 μM Ery gel + 1% TiO 2 + BL showed the highest efficacy (p = 0.05). Results of ESR showed that all Ery gel + BL groups generated significantly more singlet oxygen compared with control groups. None of the groups, however, generated detectable levels of hydroxyl radical and superoxide anion. Conclusion Erythrosine with blue light is an effective photosensitizer that can kill C. albicans, and nano-titanium dioxide acts as a catalyst that enhances the effect of erythrosine.

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Section: Discussionsupporting

confidence: 93%

Section: Discussionmentioning

confidence: 67%

Fungicidal effect of combined nano TiO2 with erythrosine for mediated photodynamic therapy on Candida albicans: an in vitro study

et al. 2017

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“…Being diamagnetic, this species is not detected by EPR. However, 1 O 2 may react with the spin probe 4-oxo-TMP to give a nitroxide radical as previously reported by other authors (Konaka et al 1999;Brezova et al 2005). By irradiation of the pristine powder in the presence of spin probe, a threeline signal typical of the nitroxide radical was obtained (Fig.…”

Section: Generation Of Singlet Oxygensupporting

confidence: 77%

Inhibition of the ROS-mediated cytotoxicity and genotoxicity of nano-TiO2 toward human keratinocyte cells by iron doping

et al. 2014

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Inhibition of the ROS-mediated cytotoxicity and genotoxicity of nano-TiO 2 toward human keratinocyte cells by iron doping J Nanopart Res (2014) Nano-TiO 2 powders are widely used in sunscreen lotions as UV filters in combination with other substances. The activation of TiO 2 by UV rays leads to the release of reactive oxygen species (ROS, e.g., hydroxyl radicals and singlet oxygen) which are potentially harmful. For this reason the TiO 2 particles are generally coated with inert materials (e.g., silica or alumina) that inhibit such reactivity. Alternatively, the release of ROS may be inhibited by introducing in the TiO 2 lattice doping elements. In the present study we report a new modification consisting in a wet impregnation of TiO 2 with iron salts followed by a thermal treatment that results in an inhibition of the surface reactivity. The insertion of iron ions also gradually reduces the ability of photo-activated TiO 2 to cleave DNA and proteins. At the same time, a clear inhibition of cyto-and geno-toxicity toward human (HaCaT) keratinocytes was observed. The data presented herein suggest the insertion of Fe 3+ ions at the surface of nano-TiO 2 as a promising strategy to reduce the photo-induced toxicity of nano-TiO 2 powders.

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“…Another way to probe the role of 1 O 2 during photocatalysis is to run the experiment in water and in heavy water (D 2 O). The lifetime of singlet oxygen in D 2 O is~20 times longer than in H 2 O, thus singlet oxygen mediated processes are dramatically enhanced in D 2 O compared to H 2 O. Singlet oxygen production has also been monitored by ESR spectroscopy using a trapping agent (173).…”

Section: Measurement Of Rosmentioning

confidence: 99%

Chapter Green Nanotechnology: Development of Nanomaterials for Environmental and Energy Applications

Fagan

Cui

Andersen

et al. 2013

ACS Symposium Series

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This book chapter discusses the syntheses of various nanomaterials, for green nanotechnology applications in detail. Special attention is given to the development of emerging areas, such as environmental as well as energy materials. Various approaches for preparing nanostructured photocatalysts, such as titanium dioxide, zinc oxide, iron oxide, and metal sulfides, different conventional methods and novel methods, including

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Irradiation of titanium dioxide generates both singlet oxygen and superoxide anion

Cited by 194 publications

References 22 publications

Fungicidal effect of combined nano TiO2 with erythrosine for mediated photodynamic therapy on Candida albicans: an in vitro study

Fungicidal effect of combined nano TiO2 with erythrosine for mediated photodynamic therapy on Candida albicans: an in vitro study

Inhibition of the ROS-mediated cytotoxicity and genotoxicity of nano-TiO2 toward human keratinocyte cells by iron doping

Chapter Green Nanotechnology: Development of Nanomaterials for Environmental and Energy Applications

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