Formation of singlet molecular oxygen associated with the formation of superoxide radicals in aqueous suspensions of TiO2 photocatalysts

Daimon, Toshihiro; Hirakawa, Tsutomu; Kitazawa, Masahiro; Suetake, Junya; Nosaka, Yoshio

doi:10.1016/j.apcata.2008.02.012

Cited by 153 publications

(99 citation statements)

References 36 publications

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“…Thompson 728,834,[867][868][869][870][871][872][873][874][875], with two groups examining this phenomenon in detail. Nosaka's group [872][873][874] used transient spectroscopy and phosphorescent markers to follow 1 O 2 formation over a variety of TiO 2 samples. These authors proposed that 1 O 2 was formed during back-electron transfer from O − 2 to the TiO 2 surface (most likely at a VB hole).…”

Section: Electron Scavengers: Omentioning

confidence: 97%

A surface science perspective on TiO2 photocatalysis

Henderson

2011

Surface Science Reports

1,855

1,634

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a b s t r a c tThe field of surface science provides a unique approach to understanding bulk, surface and interfacial phenomena occurring during TiO 2 photocatalysis. This review highlights, from a surface science perspective, recent literature that provides molecular-level insights into photon-initiated events occurring at TiO 2 surfaces. Seven key scientific issues are identified in the organization of this review. These are: (1) photon absorption, (2) charge transport and trapping, (3) electron transfer dynamics, (4) the adsorbed state, (5) mechanisms, (6) poisons and promoters, and (7) phase and form. This review ends with a brief examination of several chemical processes (such as water splitting) in which TiO 2 photocatalysis has made significant contributions in the literature.

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Section: Electron Scavengers: Omentioning

confidence: 97%

A surface science perspective on TiO2 photocatalysis

Henderson

2011

Surface Science Reports

1,855

1,634

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“…It has been also reported that a combination of anatase and rutile exhibits enhanced photocatalytic features . In the presence of UV light, TiO2 is activated to produce reactive oxygen species such as hydroxyl radicals, superoxide anions and singlet oxygen (Daimon et al, 2008). Indeed, the risk of damage to DNA and RNA, caused by the photocatalytic effect of nano-TiO2 after absorption of UV light, can be prevented by particles coating with organic and inorganic materials (Serpone et al, 2007).…”

Section: Introductionmentioning

confidence: 99%

The influence of surface charge and photo-reactivity on skin-permeation enhancer property of nano-TiO2 in ex vivo pig skin model under indoor light

Peira

Turci

Corazzari

et al. 2014

International Journal of Pharmaceutics

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Several topical products contain nanometric TiO2 (nano-TiO2), which is an useful and safe component that absorbs UV light and does not cross skin barrier. However nano-TiO2 may impregnate the first layer of the skin (stratum corneum, SC) and generate free radicals, even under low UV irradiation. These properties, largely dependent on TiO2 surface chemistry, may modulate the transdermal drug permeation. To investigate how TiO2 surface properties affect drug permeation, Amphotericin in two different media, in the presence of three differently coated samples, was applied on skin and the flux measured. The naked, but not the coated, nano-TiO2 showed enhancer property, with a fourfold increase of the drug flux. Only the positively-charged naked TiO2 strongly adhered to and altered the SC structure. The oxidative potential towards formate anion and linoleic acid was assessed and a molecular mechanism to elucidate increased skin permeability proposed.To enhance the drug permeation, both a surface charge-driven adhesion and an oxidative disorganization of the SC lipids are required. By modulating TiO2 surface charge (coating) and its oxidative potential (crystalline phase), the enhancer effect of nano-TiO2 may be tuned and turned up or down when transdermal penetration of drug has to be favored or impaired.

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“…Photocatalysis mainly uses a semiconductor such as TiO 2 which can absorb UV light (k < 400 nm) and can photo-stimulate redox reactions on its surface producing Reactive Oxygen Species (ROS) such as hydroxyl radical (·OH), superoxide radical (·O 2 − ) [22] and singlet oxygen ( 1 O 2 ) [23], and the production of them may contribute to the biocidal activity with strong oxidative activity and destroy organic compounds [24].…”

Section: Introductionmentioning

confidence: 99%

Broad Spectrum Microbicidal Activity of Photocatalysis by TiO2

et al. 2013

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Photocatalytically active titanium dioxide (TiO 2 ) is widely used as a self-cleaning and self-disinfecting material in many applications to keep environments biologically clean. Several studies on the inactivation of bacteria and viruses by photocatalytic reactions have also been reported; however, only few studies evaluated the spectrum of the microbicidal activity with photocatalysis for various species. There is a need to confirm the expected OPEN ACCESSCatalysts 2013, 3 311 effectiveness of disinfection by photocatalysis against multidrug-resistant bacteria and viruses. In this study, microbicidal activity of photocatalysis was evaluated by comparing the inactivation of various species of bacteria and viruses when their suspensions were dropped on the surface of TiO 2 -coated glass. Gram-positive bacteria, e.g., methicillin-resistant Staphylococcus aureus, vancomycin-resistant Enterococcus faecalis, and penicillin-resistant Streptococcus pneumoniae, were easily inactivated by photocatalysis, whereas some gram-negative bacteria, e.g., Escherichia coli and multidrug-resistant Pseudomonas aeruginosa, were gradually inactivated by photocatalysis. Influenza virus, an enveloped virus, was significantly inactivated by photocatalysis compared with feline calicivirus, a non-enveloped virus. The effectiveness of microbicidal activity by photocatalysis may depend on the surface structure. However, they are effectively inactivated by photocatalysis on the surface of TiO 2 -coated glass. Our data emphasize that effective cleaning and disinfection by photocatalysis in nosocomial settings prevents pathogen transmission.

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Formation of singlet molecular oxygen associated with the formation of superoxide radicals in aqueous suspensions of TiO2 photocatalysts

Cited by 153 publications

References 36 publications

A surface science perspective on TiO2 photocatalysis

A surface science perspective on TiO2 photocatalysis

The influence of surface charge and photo-reactivity on skin-permeation enhancer property of nano-TiO2 in ex vivo pig skin model under indoor light

Broad Spectrum Microbicidal Activity of Photocatalysis by TiO2

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