Carbon nanotubes quench singlet oxygen generated by photosynthetic reaction centers. Issue 12 (18th October 2013)

• Record Type: Journal Article
• Authors: Boldog, Peter; Hajdu, Kata; Magyar, Melinda; Hideg, Éva; Hernádi, Klara; Horváth, Endre; Magrez, Arnaud; Nagy, Krisztina; Váró, György; Forró, Laszlo; Nagy, Laszlo
• Is Part Of: Physica status solidi. Volume 250:Issue 12(2013:Dec.)
• Page Start: 2539
• Page End: 2543
• Publication Date: 2013-10-18
• Subjects: Solid state physics -- Periodicals; Solids -- Periodicals; Atomic structure -- Periodicals; 530.41
• DOI: 10.1002/pssb.201300074
• Languages: English
• ISSNs: 0370-1972

Abstract

<abstract abstract-type="main" xml:lang="en"> <title> <x xml:space="preserve">Abstract</x> </title> <sec id="pssb201300074-sec-0001" sec-type="section"> <p>Photosensitizers may convert molecular oxygen into reactive oxygen species (ROS) including, e.g., singlet oxygen (<sup>1</sup>O<sub>2</sub>), superoxide anion (<alternatives><inline-graphic mimetype="image" xlink:href="ark:/27927/pgg3z8s4j4p" xlink:type="simple" xmlns:xlink="http://www.w3.org/1999/xlink" /><mml:math altimg="urn:x-wiley:03701972:media:pssb201300074:pssb201300074-math-0001" display="inline" overflow="scroll" xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:msubsup><mml:mi mathvariant="normal">O</mml:mi><mml:mn>2</mml:mn><mml:mrow><mml:mo>−</mml:mo><mml:mo></mml:mo></mml:mrow></mml:msubsup></mml:mrow></mml:math></alternatives>), and hydroxyl radicals (<sup></sup>OH), chemicals with extremely high cyto‐ and potential genotoxicity. Photodynamic ROS reactions are determinative in medical photodynamic therapy (cancer treatment with externally added photosensitizers) and in reactions damaging the photosynthetic apparatus of plants (via internal pigments). The primary events of photosynthesis take place in the chlorophyll containing reaction center protein complex (RC), where the energy of light is converted into chemical potential. <sup>1</sup>O<sub>2</sub> is formed by both bacterial bacteriochlorophylls and plant RC triplet chlorophylls in high light and if the quenching of <sup>1</sup>O<sub>2</sub> is impaired. In plant physiology, reducing the formation of the ROS and thus lessening photooxidative membrane damage (including the RC protein) and increasing the efficiency of the photochemical energy conversion is of special interest. Carbon nanotubes, in artificial systems, are also known to react with singlet oxygen. To investigate the possibility of <sup>1</sup>O<sub>2</sub> quenching by carbon nanotubes in a biological system, we studied the effect of carbon nanotubes on <sup>1</sup>O<sub>2</sub> photogenerated by photosynthetic RCs purified from purple bacteria. 1, 3‐Diphenylisobenzofuran (DPBF), a dye responding to oxidation by <sup>1</sup>O<sub>2</sub> with absorption decrease at 420 nm was used to measure <sup>1</sup>O<sub>2</sub> concentrations. <sup>1</sup>O<sub>2</sub> was produced either from a photosensitizer (methylene blue) or from triplet photosynthetic RCs and the antioxidant capacity of carbon nanotubes was assessed. Less <sup>1</sup>O<sub>2</sub> was detected by DPBF in the presence of carbon nanotubes, suggesting that these are potential quenchers of this ROS.</p> </sec> </abstract>