Dataset Information

Melanin photosensitization and the effect of visible light on epithelial cells.

ABSTRACT: Protecting human skin from sun exposure is a complex issue that involves unclear aspects of the interaction between light and tissue. A persistent misconception is that visible light is safe for the skin, although several lines of evidence suggest otherwise. Here, we show that visible light can damage melanocytes through melanin photosensitization and singlet oxygen (1O2) generation, thus decreasing cell viability, increasing membrane permeability, and causing both DNA photo-oxidation and necro-apoptotic cell death. UVA (355 nm) and visible (532 nm) light photosensitize 1O2 with similar yields, and pheomelanin is more efficient than eumelanin at generating 1O2 and resisting photobleaching. Although melanin can protect against the cellular damage induced by UVB, exposure to visible light leads to pre-mutagenic DNA lesions (i.e., Fpg- and Endo III-sensitive modifications); these DNA lesions may be mutagenic and may cause photoaging, as well as other health problems, such as skin cancer.

SUBMITTER: Chiarelli-Neto O

PROVIDER: S-EPMC4236153 | biostudies-literature | 2014

REPOSITORIES: biostudies-literature

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Melanin photosensitization and the effect of visible light on epithelial cells.

Chiarelli-Neto Orlando O Ferreira Alan Silva AS Martins Waleska Kerllen WK Pavani Christiane C Severino Divinomar D Faião-Flores Fernanda F Maria-Engler Silvya Stuchi SS Aliprandini Eduardo E Martinez Glaucia R GR Di Mascio Paolo P Medeiros Marisa H G MH Baptista Maurício S MS

PloS one 20141118 11

Protecting human skin from sun exposure is a complex issue that involves unclear aspects of the interaction between light and tissue. A persistent misconception is that visible light is safe for the skin, although several lines of evidence suggest otherwise. Here, we show that visible light can damage melanocytes through melanin photosensitization and singlet oxygen (1O2) generation, thus decreasing cell viability, increasing membrane permeability, and causing both DNA photo-oxidation and necro- ...[more]

PMID: 25405352

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Project description:Water pollution is one of the global threats severely affecting our planet and human health. Organic textile dyes are one of the common organic water pollutants that are presentient to degradation by traditional physical methods. Semiconductor-assisted photocatalysis is considered a green, efficient, and sustainable technology for wastewater treatment. To maximize the efficient utilization of solar radiation, it is of pivotal significance to explore novel organic molecules to be employed as efficient dye sensitizers for wide-bandgap semiconductors to extend their performance to the Visible-light region. Hence, in this work, we are proposing the design and synthesis of novel structures of QAD molecule as a dye photosensitizer with extended visible light absorptivity due to the extended π-π/n-π conjugations, to promote the performance of TiO2 nanoparticles to the visible-light region and enhance the charge separation. The physicochemical characterizations confirmed the successful synthesis of QAD, TiO2, and QAD/TiO2 samples with the proposed structures. The anchoring of QAD molecules on the surface of TiO2 caused a substantial improvement in the optical characteristics of TiO2 as well as overcoming its common drawbacks by decreasing its bandgap energy to 2.6 eV, a remarkable reduction of PL intensity indicating reducing the e-h recombination and enhancing the charge separation, and creation of efficient visible light-harvesting antenna in the range of 400-600 nm. Besides, the QAD/TiO2 sample achieved a 3-fold enhancement in the observed rate constant of the photodegradation of Rhodamine B dye compared to the bare TiO2. The parameters affecting the photodegradation process were optimized and the sample displayed outstanding stability after 4 consecutive cycles. Finally, the effect of the scavengers was investigated and [Formula: see text] was proposed to be the most reactive species and the mechanism of the enhancement was suggested based on the electron injection from the QAD's HOMO level to the TiO2's CB. Finally, this work opens the door for various studies for the investigation of the proposed structures or similar structures in various photocatalytic/biomedical applications.

Dataset Information

Melanin photosensitization and the effect of visible light on epithelial cells.

Publications

Melanin photosensitization and the effect of visible light on epithelial cells.

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