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Peptide nanostructures have recently been identified as an important bio-functional nanostructure.  Researchers have demonstrated that modification of these peptide nanostructures can greatly expand their biological applications.

In this work, Minjoong Yoon and colleagues from Chungnam National University, Republic of Korea, have prepared peptide nanoribbons (PNRs) impregnated with a Sn-porphyrin via solvothermal self-assembly.  The resulting nanoribbons are highly fluorescent and thermo-stable.  However, the fluorescence intensity and life-time were selectively affected upon interaction with the nucleotide base sequences of DNA, thus implying that these Sn-porphyrin-PNRs could be useful as a biocompatible DNA sensor.

Read the full article for free until the 7th March 2013!

Highly fluorescent peptide nanoribbon impregnated with Sn-porphyrin as a potent DNA sensor, Sreenivasan Koliyat Parayil, Jooran Lee and Minjoong Yoon, Photochem. Photobiol. Sci., 2013, DOI: 10.1039/C3PP25337F

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The human eye is photoprotected by molecular UV filters which consist of low-molecular weight compounds in the lens that absorb UV light in the 300-400 nm spectral region.  The UV filters decompose to give a mixture of products, which can include kynurenine yellow (KNY) and kynurenic acid (KNA) from the UV filter kynurenine.  These compounds have only been found in very small or negligible concentrations in the human lens which may indicate that they are much more chemically or photochemically active than the original UV filters.

In this work, Yuri Tsentalovich and colleagues from Russia, Switzerland and The Netherlands investigated the photochemistry and photophysics of neutral aqueous solutions KNY and KNA using time-resolved optical spectroscopy.  Their work has shown that both of these molecules are significantly more photoactive and photostable than the parent UV filter.  These species and their products may react with the protein environment in the lens and could contribute to the development of oxidative stress conditions – a main factor in the development of cataract.

Read this article for free until the 8th February 2013:

Photochemistry of aqueous solutions of kynurenic acid and kynurenine yellow, Ekaterina A. Zelentsova, Peter S. Sherin, Olga A. Snytnikova, Robert Kaptein, Eric Vauthey and Yuri P. Tsentalovich, Photochem. Photobiol. Sci., 2013, DOI: 10.1039/C2PP25357G

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Scientists from India used visible light activation of persulphate by a ruthenium(II) complex to investigate it’s ability to cause degradation of organic contaminants.

Halan Prakash and colleagues from the Birla Institute of Technology and Science, India, looked at the ability of persulphate to cause degradation of organic contaminants and also its effect on bacteria in aqueous media. The team used methyl orange, a model azo dye, and Gram positive and negative bacteria. Visible light activation of persulphate was achieved using ruthenium(II) polypyridyl complexes, which produced sulphate radicals and led to significant degradation of methyl orange as well as complete inactivation of bacteria.

The authors note that to take this appraoch forward and make it more practical for actual application in the environment, strategies for removal of the ruthenium photosensitizer and its degradation products need to be developed.

Read the full article for free until the 3rd January 2013!

Photodegradation of methyl orange and photoinactivation of bacteria by visible light activation of persulphate using a tris(2,2′-bipyridyl)ruthenium(II) complex, Gokulakrishnan Subramanian, Priyadarshini Parakh and Halan Prakash, Photochem. Photobiol. Sci., 2013, DOI: 10.1039/C2PP25316J

A team from Austria and Germany perform a prospective clinical trial on the effect of extracorporeal photochemotherapy in the treatment of atopic dermatitis.

Atopic dermatitis (AD) is a common, chronically relapsing inflammatory skin disease characterised by itchy eczematous skin lesions; the exact pathogenesis of AD remains unclear.  Conventional therapies, including topical corticosteroids or phototherapy is not effective in some patients particularly when the suffer from chronic disease with wide spread skin involvement. 

Extracorporeal photochemotherapy (ECP) in AD is a safe and likely effective treatment first described in 1994.  ECP is a form of phototherapy where blood is exposed outside the body to the photoactivated drug 8-methoxypsoralen (8-MOP) before being returned to the body.  Many retrospective studies have been performed but this is the first prospective study and it confirms that extracorporeal photochemotherapy is effective in severe refractory atopic dermatitis. In particular female and/or erythrodermic patients may favorably respond to the treatment.

Interested in knowing more? Read the article for free until 8^th October.

Extracorporeal photochemotherapy as systemic monotherapy of severe, refractory atopic dermatitis: results from a prospective trial
Peter Wolf, Dimitrios Georgas, Nordwig S. Tomi, Christoph M. Schempp and Klaus Hoffmann
Photochem. Photobiol. Sci., 2013, Advance Article

You may also be interested in this review article, also free to access until 8^th October.

Photopheresis (extracorporeal photochemotherapy)
Franz Trautinger, Ulrike Just and Robert Knobler
Photochem. Photobiol. Sci., 2012, Advance Article

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Nils Ryberg Finsen (1860–1904) (Courtesy of the Clendening History of Medicine Library, University of Kansas Medical Center

“Real modern phototherapy began with Niels Ryberg Finsen, the father of ultraviolet therapy. In 1896, Finsen, aware of the bacteria-destroying effects of sunlight, developed a “chemical rays” lamp with which he treated a friend who had lupus vulgaris; within a few months the lesions were completely resolved”

This perspective by Herbert Hönigsmann from the Department of Dermatology from the Medical University of Vienna gives a history of phototherapy in dermatology, describing the key developments to date.  He covers the ancient history and describes how over many centuries, treatment with sunlight or “heliotherapy” was used in the treatment of skin diseases.  He then describes the developments made in the 19^th century when observations were made that sunlight may be beneficial for medical purposes. 

In 1974 the development of photochemotherapy marked the beginning of a huge upsurge in photodermatology and the subsequent development of high intensity UV sources with defined spectra facilitated a variety of new therapies. Photodynamic therapy, first conceived at the start of the 20^th century has developed in to a routine treatment for many diseases including cancer.

The parting words of this article come from a quote from Kendric C. Smith, one of the founding fathers of the American Society for Photobioloty: “Photodermatology – The future is Bright”.

Read the article in full, free to access until 10th August:

History of phototherapy in dermatology, Herbert Hönigsmann
Photochem. Photobiol. Sci., 2012, Advance Article, DOI: 10.1039/C2PP25120E

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Naphthalenic compunds have many applications in the fluorescent sensing/switching/logic systems.  In this paper from A. Prasanna de Silva and colleagues at Queen’s University in Belfast, the team examine a naphthalenic compund which is a fluorescent photoinduced electron transfer system of the ‘fluorophore-spacer-receptor’ format, whose fluorescence responds sharply to H⁺. Several structural variations of this compund are examined and it is deomonstrated that the naphthalenic derivatives display a range of H⁺-induced fluorescence switching actions.

For all the details read the article in full for free until 31^st July:

Structural effects on the pH-dependent fluorescence of naphthalenic derivatives and consequences for sensing/switching
Shuai Zheng, P. L. Mark Lynch, Terence E. Rice, Thomas S. Moody, H. Q. Nimal Gunaratne and A. Prasanna de Silva
Photochem. Photobiol. Sci., 2012, Advance Article, DOI: 10.1039/C2PP25069A

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The photocatalytic inactivation of influenza virus using titanium dioxide thin film is demonstrated in a recently published paper from Ryuichi Nakano and co-workers from Japan.  Titanium dioxide (TiO₂) under ultraviolet (UV) light produces a strong oxidative effect and may therefore be used as a photocatalytic disinfectant.  Photocatalytic inactivation of bacteria is well known, however few studies have addressed virus inactivation. 

In this paper the inactivation of influenza virus is demonstrated using TiO₂ nanoparticles immobilized on a glass plate.  Viral titers were dramatically reduced by the photocatalytic reaction and the influence of UV intensity, irradiation time and bovine serum albumin concentration in viral suspensions was investigated.  It was demonstrated that effective inactivation occurs under an environmental level of UV-A intensity.  In addition, the International Organization for Standardization (ISO) methodology for anti-bacterial effects of TiO₂ photocatalysis can be useful for the evaluation of antiviral activity with only a small modification to the methodology.

Interested in knowing more?  Read the full article for free until June 14^th by clicking the link below!

Photocatalytic inactivation of influenza virus by titanium dioxide thin film
Ryuichi Nakano, Hitoshi Ishiguro, Yanyan Yao, Jitsuo Kajioka, Akira Fujishima, Kayano Sunada, Masafumi Minoshima, Kazuhito Hashimoto and Yoshinobu Kubota
Photochem. Photobiol. Sci., 2012, DOI: 10.1039/C2PP05414K

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In this communication recently published online as an ‘Accepted Manuscript’ Frederick Lewis and co-workers from the USA and India investigate the effect of flanking purine bases on the 3’ vs the 5’-TT dimer upon UV irradiation of DNA hairpins possessing TTT steps with flanking purine bases. 

The study demonstrates moderate to high facial selectivity for the 3’-dimer over the 5’ dimer depending on the identity and location of flanking purine bases.  The effects of flanking purines on facial selectivity are attributed to a combination of their ground state conformational effects and electron transfer quenching.

Interested in knowing more? Read the full article for free until June 13th.

Facially-Selective Thymine-Thymine Photodimerization in TTT Triads
Prakash P Neelakandan, Zhengzheng Pan, Mahesh Hariharan and Frederick D Lewis
Photochem. Photobiol. Sci., 2012, Accepted Manuscript, DOI: 10.1039/C2PP25089F

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